Another look into why South America has so many birds

The Andes: one of the defining geographical features of South America, filled with unique cultural and biological heritage — and a source of ornithological debate since the 1910s.

Why?

To answer this question, let’s return to the fascinating field of biogeography (which we have visited before here and here). Focusing on how species distributions change in space and time, biogeography is unsurprisingly interested in places where there are lots of species. If diversity is high, something has happened to generate it. And that something, whatever it is, probably started with geography.

In the world of biogeography, mountain ranges like the Andes are of particular interest. Rising mountains brings about new ecological opportunity at ever-higher elevations, providing resources for the taking by those species that could adapt to the uplift. This process eventually led to distinct communities in each elevational “band.”

For those species that couldn’t adapt to new elevations, the uplift of the Andes would have split up their once continuous lowland distribution. Unable to adapt to high elevations, the lowland species would had to heed the rising Andes as a barrier, becoming gradually disconnected with their counterparts on the other side. Simply enough, right?

Well, it may not be that simple. Yes, the Andes split many bird distributions that were once continuous. But birds can fly. And the entire Andean range isn’t all the same high elevation. Where there are peaks, there must also be valleys and passes. Couldn’t the birds disperse across the range via these valleys?

Admittedly, assuming that the Andes was the main event that split up once-continuous bird distributions is an elegant model. It’s simple, it makes sense, and it can be applied to all sister species on either side of the Andes. If there’s anything that theory-builders want, it’s universality. Theoreticians want to be their field’s own Newton, discerning universal laws by which everything they study must abide.

In 1917, AMNH ornithologist Frank Chapman posited that once the Andes rose, the species splits it caused were final. He envisioned “a pre-Andean fauna, the Pacific portion of which has been cut off from that of upper Amazonia by the Andean uplift.” To him, it made the most sense to think of South American avifauna in terms of before and after the uplift of the Andes, basically denying that dispersal across the Andes occurred much if at all.

For a long time, this assumption held, in part because of its simplicity: the uplift of mountains leading to allopatric speciation. It’s perfect for textbooks.

Moving forward to the 1960s and 70s, the question of dispersal came to the fore. Jürgen Haffer, the creator of the theory of Amazonian forest refugia, wasn’t satisfied with Chapman’s model. Originally trained as a geologist, he realized that much of Western South America was covered by shallow seas before the Andean uplift. As such, there wouldn’t have been any continuous ranges split up by the new mountain range. Instead, the uplift of the Andes would have created new rainforest landscape to their west. Still supporting that the Andes resulted in speciation to the East and West, Haffer argued that the uplift on its own is not what caused it. Instead, he posited that dispersal through Andean valleys during climatically humid periods is what allowed allopatric speciation later. When the climate is generally more humid, lowland rainforest can expand upward into higher elevations, allowing lowland species to spread where they couldn’t before. With Haffer’s model, we expect periodic dispersal through the Andes to be the main cause of increasing bird diversity (diversification), not the uplift of the Andes itself.

In order to put Chapman’s model and Haffer’s model to the test, we need to look at species whose closest relative (sister species) is right on the other side of the Andes. If the molecular clocks in DNA show that speciation occurred around the same time that the Andes rose, Chapman’s simple model triumphs. If speciation has occurred episodically through history, with no correlation with the uplift of the Andes, Haffer’s dispersal model wins out.

Since 2000, a number of comprehensive analyses (see citations for just a few) of South American bird speciation have formed a scientific consensus: Haffer was on the money. The data support that speciation was initiated by dispersal across the Andes. Remarkably, a geological event at as massive a scale and as rapid a rate as the Andean uplift was not what had the most influence on bird diversification. Instead, those periods of time when birds were triumphant at traversing the new mountain range, when the climate was just right, had the most influence. It’s not the barrier itself. It’s the episodic cross of the barrier that counts.

In spite of the elegant simplicity of Chapman’s model, I delight in Haffer’s dispersal model. Why? Because this model allows for idiosyncrasy; every species could have its own unique pattern of dispersal and diversification across the Andes. There may not be universality, but it makes for a richer story behind the vast diversity of birds in South America.

A diversity of stories to match a diversity of birds? Sounds about right to me.

Citations:

Cadena, Carlos Daniel, Carlos A. Pedraza, and Robb T. Brumfield. “Climate, habitat associations and the potential distributions of Neotropical birds: Implications for diversification across the Andes.”Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 40.155 (2016): 275–287.

Miller, Matthew J., et al. “Out of Amazonia again and again: episodic crossing of the Andes promotes diversification in a lowland forest flycatcher.” Proceedings of the Royal Society of London B: Biological Sciences 275.1639 (2008): 1133–1142.

Smith, Brian Tilston, et al. “The drivers of tropical speciation.” Nature 515.7527 (2014): 406–409.

Of Mountains and Valleys was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

A jaunt into a fascinating evolutionary inquiry

Even since before the times of Charles Darwin, naturalists have been engaged in dogged pursuit of what produces species. Encompassed in this question is a rich treasure trove of potential research questions: what produces variation in a population? What causes species to look and/or act differently from other species? How are these things affected by landscape, climate, and the presence of other species?

As you might be able to tell by reading through this publication, these questions are on my mind a lot. And I’m not alone. The origin stories of species and their many unique characteristics engages academics at almost every major institution, and serves as a muse to students considering a research career for themselves.

Among these academics are Emily Hudson, a Ph.D. candidate at University of Nebraska — Lincoln, and Trevor Price, a Professor at University of Chicago. Price’s research career has basically addressed the problem of species: why do we have them? why are there so many? how quickly do they evolve? And of course, given that their work would show up on this publication, they both use birds as their study system.

These two researchers, one at the outset of her career and the other well-established and highly respected, published a paper in 2014 titled, Pervasive Reinforcement and the Role of Sexual Selection in Biological Speciation. In it, they sought to uncover how sexual selection, rather than natural selection, has an influence on speciation (Speciation, as a reminder, is when two populations that were once unified evolve differences. Among these differences is one critical difference: they don’t mate much if at all with each other. In this writing, I’ll call populations that are on the way to becoming species “potential species”). Hudson and Price, like many other ornithologists, observed something peculiar: some closely related species evolve to look very different, while others remain similar looking even after they have speciated. They also noticed that a lot of the traits that do tend to evolve differences between species are related to reproduction. The shiny blue patch on a male’s head, the dazzling red color on the throat, or the intriguing black-and-white zebra stripes along the flanks. All these traits–secondary sexual traits–are subject to sexual selection.

With this in mind, their question was this: does differentiation in these sexually selected traits affect whether or not two populations will mate with each other? In other words, do differences in appearance affect whether two potential species will hybridize?

First, a little background. These questions are tied intimately to whether two potential species exist in the same range (in sympatry), or if they are geographically separated (in allopatry). If two potential species are found in the same places, it is much more likely that they will hybridize, and eventually fuse back into one species.

It turns out that this sympatry problem is a pretty insurmountable one, at least in birds. Instead, most speciation happens in allopatry. Geographically separated, two potential species can evolve species-level differences without the homogenizing interference of genes flowing from the other potential species.

Hudson and Price’s paper discusses one critical detail in this process: while in allopatry, both potential species’ mate preferences and ability to recognize members of their own species diverge. Their so-called “windows of recognition” change, eventually leaving them only able to recognize members of their own species as potential mates.

This is where differences in appearance comes in. If the two potential species evolve differences in appearance while in allopatry, those differences become intimately connected to their window of recognition, i.e. if a bird doesn’t exhibit a given set of traits, it won’t be recognized as a potential mate.

But REMEMBER: all of this evolves. Species, which are made of many individuals, don’t pass from one state to the next in immediate changes. Differences in appearance evolve gradually through time, as do changes in the window of recognition.

After some period of time, environmental and/or climatic changes will cause the allopatric potential species to again make contact, a phenomenon called secondary contact. Here, the two potential species are put to the test: will they have evolved different enough appearances &/or different enough windows of recognition to remain distinct? Or will they still be similar enough that they will fuse back into one species with pervasive reproduction between populations?

The answers to these questions depends on the system we’re looking at, and on how much time the potential species spent in allopatry.

What Hudson and Price wanted to know was this: in species that remain distinct during secondary contact, what matters more: Divergence in appearance, or divergence in windows of recognition?

If the former is the case, we would expect that species that look very different are always the more distinct species. But this just isn’t the case in birds. Many groups (Scytalopus tapaculos, Phylloscopus Leaf Warblers, Certhia creepers, to name a few) contain species who have been distinct for a very long time, and yet remain near-identical, at least to humans.

After doing phylogenetic, morphological, and bioacoustic analyses, Hudson and Price discovered that divergence in secondary sexual traits is poorly correlated with completed speciation. Just because a bird looks distinct in traits that sexual selection acts on does not mean it is a more distinct species.

Instead, Hudson and Price think that it’s the window of recognition that matters most. As long as a female bird can tell who is and who isn’t a potential mate, it doesn’t matter how similar the species are. Divergence in appearance isn’t always a given, which lines up with what we observe in the world’s diverse avifauna.

If the windows of recognition have diverged far enough and are narrow enough, sexual selection can lead to reinforcement, when two potential species are naturally selected to remain separate. If the window of recognition is what matters, then we have a fascinating mechanism of reinforcement: hybrid males may be just different enough that females in either of their parental species won’t recognize him as a potential mate (we’d call this a narrow window of recognition). This puts hybrids at a selective disadvantage, and simultaneously reinforces speciation. Alternatively, if the window of recognition is too broad, females in either of the potential species have no problem mating with males from the other population. Hence, the populations fuse, and any potential they had to become distinct species is lost.

Pretty cool, eh? It’s in thinking about things in this evolutionary fashion that we realize that appearances coevolve with abilities to perceive. By continuing to investigate how perception coevolves with appearance, we may finally understand what has brought about the extravagant diversity in birds. Along the way, we march ever forward to see whether our explanations with be refuted, or reinforced.

Citation:

Hudson, Emily J., and Trevor D. Price. “Pervasive reinforcement and the role of sexual selection in biological speciation.” Journal of Heredity 105.S1 (2014): 821–833.

Why do only some species look different? was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

Or, why identifying one group of birds can be a nightmare for birders & geneticists alike

Hundreds of miles out of place, a confused olive bundle was captured one winter day in Virginia. A member of the infamously difficult-to-identify genus Empidonax, this bird elevated the challenge to an extreme. Even with DNA analysis, this bird would require a full scientific investigation, teaching us that sometimes, even an organism’s identity is no simple matter. In a place that was cold, wet, and not particularly accommodating for a wayward insectivore, this bird reminded us that:

“Nature was not designed to make life easy for biologists.”

Of course, species that are classified in the genus Empidonax are known for their external similarities. In many cases, their identity can only be confirmed with the help of their distinctive calls. But for the Virginia bird, this is precisely the problem: in the middle of the nonbreeding season — like January — “Empids” have little reason to vocalize.

The story starts like this: on January 27th, 2013, ornithologists at Old Dominion University were conducting their usual banding session at the Virginia Zoo. Capturing birds in near-invisible mist nets draped about the station, the group encountered an unexpected bird that had all the drab ‘oliveness’, wing bars, flat bill, and body structure unique to the genus Empidonax. Still, the team could not give it a leg-band. To band a bird, one needs to have identified its species, but this drab bird with worn plumage, representing a genus whose plumages are often not distinguishable even when fresh, had to go without.

Remarkably, the bird was caught again in the same location nearly a month later, on February 23rd. Given the time of year, the bird was beginning to molt. While being removed from the mist net, the bird shed four tail feathers — an opportunity.

It was time to figure out what this out-of-place bird was.

Realizing that this bird may represent a rarity for Virginia, the ornithologists sent two of the shed feathers to Washington D.C. There, the Smithsonian Institution’s Feather Identification Lab extracted DNA to sequence one special gene. The gene, known first as cytochrome c oxidase I (COI), is alternatively called the DNA Barcode Gene for its part in The Barcode of Life Project. The BOL Project’s grand vision is simple: facilitate genetic identification of species by sequencing an informative gene for as many species as possible. What does this mean?

It’s all in the sequence. Overtime, all of an organism’s genome has the potential to undergo change, even if in small amounts — the basis of biological evolution. But some parts of the genome change more rapidly than others.

In looking for an informative gene, what we need is a rate-of-change that is just right, a gene that changes over time at about the same rate that species split from one another. That way, the gene sequence — a progression of the nucleotides A, T, G, and C — will be unique for each species. (We can expect this because of the extraordinarily low chance that the same mutation will happen twice.)

In animals, the COI gene has a good track record for being informative. In sequencing the COI gene from as many species as possible, the BOL project will create a database of species “barcodes”, allowing researchers to identify any species by matching their specimen’s barcode sequence to one in the database. The whole process is very similar to scanning a barcode in the grocery store, except the scanning is done with benchwork and bioinformatics, not a laser gun.

In addition to barcoding the wayward Empid’s feathers, the Old Dominion team sequenced another gene — ND2 —to compare to a different database of genes: the National Institute of Health funded GenBank.

The barcoding results identified the bird as a Dusky Flycatcher with 99.8% probability, but there’s a pretty big caveat: the very closely related Pine Flycatcher doesn’t have a barcode sequenced. A 2002 study showed that much of the COI gene used for barcoding is near-identical between Dusky and Pine Flycatchers. Alas, without coverage of Pine and Dusky Flycatchers, the barcoding can’t lead to a conclusive identification. Instead, it would take a more in-depth investigation on the researchers’ part to produce robust results.

GenBank turned out not to be conclusive either. While the initial barcoding results suggested Dusky Flycatcher, GenBank’s closest match to the wayward Empid’s ND2 gene was Pine Flycatcher. Barcoding said Dusky, GenBank said Pine. The most likely explanation, then, is flawed databases. Something fishy — like an erroneous species identification or faulty gene sequence — might have made its way online. In GenBank, Dusky Flycatcher was represented by only two specimens, while Pine Flycatcher was represented by only one. This provides very little basis for comparison, and leaves open the possibility that some of the sequences are misidentified or otherwise flawed.

Even with modern molecular methods, identifying this Virginia Empid was proving to be a lengthy endeavor.

Continuing the hunt, the Old Dominion ornithologists extracted DNA from ten museum specimens — five from Dusky Flycatcher specimens and five from Pine Flycatcher specimens — for comparison, sequencing both ND2 and the barcoding COI gene. This necessary precaution makes it possible for similar specimens to group together even if they’ve been labeled as the wrong species.

Such turned out to be the case with the GenBank specimens. The two ND2 sequences labeled as Dusky Flycatcher did not match the five museum specimens of Dusky Flycatchers. The GenBank Pine Flycatcher sequence, to which the Virginia Empid was matched, was the most confounding of all, grouping together with four Dusky museum specimens and a Pine museum specimen— not the most informative sequence, and perhaps misidentified to begin with.

In the end, the wayward Empid, captured on that chilly day in late January, contained COI and ND2 genes that were most similar to Dusky Flycatcher sequences — at last, an identification.

But this ID comes with an important lesson: for online gene databases to succeed in their goal of genetically identifying species, the catalogued gene sequences must be identified correctly to begin with; otherwise, the above fiasco will be a familiar tale. For us to be sure that the online sequences are labeled correctly, we need replication. We cannot simply match our unknown specimens with one available specimen in a database. Instead, we need comparative analysis, wherein the sequences from many specimens are compared to see how similarity groups them. This approach brings more robust results, let alone a much more efficient identification.

One must marvel at how those darn Empids seem to confound us at every turn. But with investigations like these, there is progress. We learn the importance of replication, and the necessity of comparing more than one gene. We learn that past misidentifications can unknowingly be transmitted to specimens’ gene sequences, mucking up what would be straightforward identifications. And we encounter yet another example of when museum specimens are crucial for something even as simple as identifying a species.

As for the wayward Virginia Empid, this study confirmed that is was Virginia’s first-ever record for Dusky Flycatcher. This single bird led not only to excitement at the Virginia Zoo banding station, but also to a systematic revision of our online genetic databases.

The presence of a single organism, in other words, can be a significant event. Indeed, much of scientific advance depends on the contingency of nature. If ornithologists hadn’t been there at the right time, or if the bird occurred just far enough away to be missed, none of this study would have come to pass. We are surrounded by unknown unknowns, unexpected organisms all over the earth that even the most astute observers narrowly miss.

This leaves me with one nagging thought:

What’s out there that we’re missing?

Citations:

Heller, Erin L., et al. “Overcoming challenges to morphological and molecular identification of Empidonax flycatchers: a case study with a Dusky Flycatcher.” Journal of Field Ornithology (2016).

Pereyra, Maria E. and James A. Sedgwick. 2015. Dusky Flycatcher (Empidonax oberholseri), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/078, doi:10.2173/bna.78

It Took a Museum, a Lab, & Some Databases was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

In answering this question, where you look is critical.

In a good day of birding, one encounters a myriad of species. Let’s say it’s spring in the eastern United States. We’d see warblers, sparrows, blackbirds, orioles, kinglets, nuthatches, woodpeckers, hummingbirds, sandpipers…the queue of groups goes on.

Inevitably, after even a little time in the field, the birder’s mind unconsciously begins an analytic process, one which demands more and more data from more and more field experience. The birder’s mind starts categorizing species by how likely they are to see it. Based on this unconscious categorization, the birder gauges their excitement about a given sighting. Yellow-rumped Warbler in early spring? ‘Ah, more warblers are on the way.’ Kirtland’s Warbler? ‘I BETTER GET THE WORD OUT.’

Indeed, it is expected for the observer to separate the common from the rare. Our pattern-seeking minds are naturally attuned to the variance in birds’ frequency, and it is often this tuning that guides our decision-making in where to go for a morning’s birding.

Too often, we take this process for granted, as if some birds are more common by default than other birds. But why? In the eastern U.S., why are Yellow-rumped Warblers more common than Kirtland’s Warblers? Why are birders so much more excited by Slaty-backed Gulls than by Herring Gulls? What’s so much more thrilling about a Common Rosefinch than a Purple Finch?

Again, we must remind ourselves that there are natural processes, evolutionary and ecological in nature, behind these questions. Birds, like the rest of life, have evolved to fill various roles in various ecosystem. Each species fancies a particular habitat, a certain mix of vegetation, with unique food preferences. So in asking why a certain bird species is rarer or commoner than another species, we are indirectly asking about the ecosystem in which it participates.

What makes these ponderings even more fun is that birds move a lot. Many birds are long-distance migratory champions, covering hundreds of miles in a day (or night) during their seasonal forays. These journeys literally connect the ecosystems of different continents. As such, the abundance of a given bird species depends on more than the one ecosystem with which we associate it conceptually. No, it depends on every ecosystem it visits, be it to breed, to refuel, or to overwinter.

So, when we ask, “why is this bird rare,” we’re really asking a more intricate question. We’re querying the series of ecosystems it participates in.

I invite you, now, to consider the Gray-cheeked Thrush, a far northern Taiga-breeding songbird of the Canadian Shield. Unlike its abundant relative the American Robin, this species is uncommon, a fact compounded by its furtive migratory behavior. It travels so far north to breed that its breeding habits are rarely observed, and with infrequent observation comes even more infrequent study. As a result, little known about its life history.

Though its breeding habits are poorly known, at least its breeding range is fairly well established. We could make no such statement about its nonbreeding range. Travelling southward from Canadian taiga, along the Atlantic seaboard, and through the Caribbean, these gunmetal gray migrants settle down east of the Andes for the winter, known to be nonbreeders in Colombia, Venezuela, Trinidad, Guyana, and northwest Brazil — and that’s about as specific as it gets.

Overall, we know that this species has a broad breeding range, and appears to have a broad nonbreeding range. Furthermore, while its behavior is reclusive, it’s not that much more reclusive than other members of the genus — like Veery, Hermit Thrush, or Swainson’s Thrush. During migration, it is often seen by birders, only not in the same abundances as its thrush kin. As such, we can deduce that its lower frequency can be attributed to a generally lower commonness instead of under-observation.

So, why is Gray-cheeked Thrush as uncommon as it is?

As of right now, we do not have the complete answer to this question. Too little is known about its breeding habits, about its interactions with other species, about its habitat preferences, etc. But one piece of the puzzle was recently uncovered.

Scattered across the Amazon basin are white-sand terra firme forests — rainforests that are not seasonally flooded, and whose substrate is almost entirely white sand. Sandy soil means low nutrient content, which has resulted in uniquely woody, hard-leaved vegetation. It appears that this is just the habitat in which to find overwintering Gray-cheeked Thrushes.

Conducting a survey of understory avifauna, Judit Ungvari-Martin captured and banded 57 Gray-cheeked Thrushes that were frequenting this white sand terra firme forest, doing so in 19 sites for three consecutive years. Remarkably, 3 of these 57 returned to the same overwintering location between years. While this may seem like a small number, this approximately 5% site fidelity was observed in spite of the immense mortality rate of neotropical migrants (some estimate near 50% die), and the ability of migrants to simply disperse into other suitable overwintering spots. What this indicates, then, is that there may not be many suitable spots to begin with.

White sand terra firme forest covers a measly 3% of the Amazon Basin. If Gray-cheeked Thrushes only overwinter in this habitat, then we may have at least part of the explanation of their relative uncommonness. Limited overwintering habitat significantly constrains the number of birds that can survive a full year. If all the birds that breed across the Canadian Shield must fit into this 3% of Amazonia, then we can expect that there probably isn’t a very large breeding population to begin with. The breeding population must be either clustered in a few Canadian locales, or be thinly distributed across the Shield…predictions to be tested. Either way, we would definitely not expect them to be abundant across their established breeding range, and would therefore not expect them to be notably common during migration.

In this case, a birder’s reality — the uncommonness of migrating Gray-cheeked Thrushes — fits these expectations.

We learn two lessons from these expectations. First, a large distribution may not necessarily mean vast expanses of suitable habitat for that species. Though birds can theoretically show up anywhere, their habitat preferences make it unlikely that they will. Second, sometimes looking by default at the breeding range is the wrong place to look. If limits on population size don’t appear to exist in a bird’s breeding range, they may yet exist in their nonbreeding range. One must holistically study a bird’s full annual cycle — including all the ecosystems it visits — to understand just why a bird is abundant or rare.

So, we see that observing which birds are common and which are rare is one thing. But asking why they are common or rare connects us not only more deeply to a bird’s annual cycle, but also to the ecosystems that support it.

Birds are global citizens. In asking questions about them, we have to think more globally ourselves.

Where around the globe might your bird questions bring you?

Citations:

Ungvari‐Martin, Judit, Christopher M. Heckscher, and Keith A. Hobson. “Inter‐annual site fidelity and breeding origins of Gray‐cheeked Thrushes in white sand forests of the Peruvian Amazon.”Journal of Field Ornithology (2016).

Lowther, Peter E., Christopher C. Rimmer, Brina Kessel, Steven L. Johnson and Walter G. Ellison. 2001. Gray-cheeked Thrush (Catharus minimus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:http://bna.birds.cornell.edu/bna/species/591

Why is this bird rare? was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

Take a good look at the image above. Dry, prickly, windswept, and vast. This is part of the valley carved into the Peruvian landscape by the Marañon River. Long considered the source of the Amazon River, this ancient tributary has left an indelible mark on both the landscape and the birds that live there.

In the tropics, the exquisite diversity of life dwells upon a scaffold of geographical features like the Marañon. Every feature tells a story to those who listen, whispering clues of its role in organizing the diversity of life we see today. In one locale, we find one unique cluster of species, while in the next, we observe a different cluster. Investigating this pattern often starts with studying geography. In doing so, we come closer to understanding not only why life is organized as it is in the tropics, but also to understanding why it’s so diverse in the first place.

There are many explanations of why and how the tropics are so diverse. Some claim it’s the wide variety of resources there, providing the fodder populations need to split into many species. Others point to the climatic stability of tropical regions, where events like glaciation have never brought about high extinction rates. Without these extinctions to open up resources, natural selection favors more and more adaptation to a particular resource. As species go through this process, they benefit from more efficient use of their resource-specialty. But like a picky child eating only their preferred foods off their dinner plate, specialized species leave more resources unused the more they specialize. As species subdivides resources at a finer scale, allowing species to subdivide as well, making it possible for more species to coexist in a given area without risking competition.

As is often the case in ecology and evolution, these explanations are intertwined. But at least with birds, geography stands out among them as consistent factor. Indeed, the surest way to get two (or more) species from one is to subdivide them into different geographic areas.

This is exactly what the Marañon Valley does, dividing a homogeneous tropical landscape — and the organisms that live there —in two with an inhospitable arid valley.

Of course, this valley isn’t inhospitable for all organisms. There are certainly plants there, and these plants produce energy that sustain other organisms. How can the valley have the power to split bird populations that can fly? Around this valley exists humid montane rainforest, filled with a myriad of ecologically picky bird species. These picky, often sedentary species are not likely to disperse far from their favored habitat, let alone across a broad and dry valley. To them, it is inhospitable, appearing other-worldly in comparison to the rainforest they call home. A key is that when birds aren’t crossing the valley, neither are their genes. Without interbreeding, populations on either side of the valley are free from homogenizing gene flow, and can proceed to differentiate into distinct species. This is why the Marañon Valley is an effective biogeographic barrier. It isolates habitat on either side that sustains similar bird communities, and acts as a near perfect stage for observing the process of differentiation.

Rarely, though, dispersal does occur. Bird populations are tricky in that dispersal — the propensity to spread into new areas — changes idiosyncratically. Depending on the climate, a given bird species may disperse frequently, only to become practically sedentary a millennium or two later.

These rare dispersal events have occurred randomly throughout history, leading to bird species that have been split by the Marañon Valley for various amounts of time. Some populations (and their genes) have been isolated from their sister population on the other side for a long time, whereas others have been isolated for a short amount of time. Those that have remained separated for long enough have accumulated enough differences to diverge into two species. Those that have been experiencing dispersal across the valley may remain similar enough to be considered the same species.

This pattern is obvious around the Marañon Valley. Many species on one side of the valley share a common ancestor with a species on the other side—two species that were one until the valley separated them. Inhabiting similar habitat on both sides of the Marañon Valley, they face similar challenges, benefit from the same adaptations, and partake in similar if not identical ecosystems. They still behave similarly, feed on the same things, nest in similar ways, and displaying similar reproductive strategies.

And yet, they look different.

But wait — if they are still ecologically similar to each other, why do they look different? This, my friends, is the key question, and is why the Marañon Valley and its divided avifauna are so interesting. We will employ an exciting recent study to answer it.

Enter a 2015 study by Benjamin Winger, of University of Michigan, and John Bates, of Chicago’s Field Museum of Natural History titled The tempo of trait divergence in geographic isolation: Avian speciation across the Marañon Valley of Peru. The study relied on the Marañon Valley’s capacity as a natural experiment, where populations can be observed at multiple stages in the process of differentiation.

The authors sampled three species from eight genera, 24 species in all. Within each genus, one of the three species had to appear roughly the same on both sides of the Marañon Valley (called the “monotypic” species). The next two species had to be each other’s “sister”, once one species that was later divided by the Marañon Valley. Presumably, the monotypic species would have low genetic divergence (how different their DNA is) to match their similar appearances. The sister species, on the other hand, were expected to have been separated for longer, with more genetic divergence to match any differentiation in their appearance. To ensure that the results weren’t skewed by the adaptation that new environments demand, all sampled species occupied humid montane forest, where species tend to be ecologically picky and to have limited dispersal across the valley. This way they would be certain to learn something about why species evolve different appearances even when their environments provide no reason to.

With these 24 species as their study system, Winger and Bates began collecting data. They sampled a part of their mitochondrial DNA known to be useful as a molecular clock. They measured plumage color using spectrophotometry and a scoring system. They measured body proportions, and analyzed vocalizations using bioacoustics software. With these measurements from each species, Winger and Bates’ goal was to determine how long it takes species to evolve differences in appearance around Marañon Valley, not to mention why they evolve differences at all.

It seems intuitive to think that populations would evolve more differences before the process of splitting into different species. After all, what we call different species tend to look very different. Don’t those differences lead to speciation, when populations that were once one species lose their propensity to interbreed?

In some cases, yes. The opportunity of new resources results in the kind of differentiation that occurs before speciation. If resources are available, natural selection favors populations that subdivide to seize these new opportunities. As these sub-populations adapt to the new resources, they change in appearance, and eventually speciate. A classic example of this is the adaptive radiation of Darwin’s Finches, each adapting to their own niche after arriving on the Galapagos.

But in the case of the Marañon Valley, Winger and Bates found that bird populations evolved differences after they were split by the valley. Here, we return to our big question:

If two species are still ecologically similar to each other, why would they evolve to look different?

On their way to a possible answer, the Winger and Bates determined a threshold amount of time for separated species to start looking different: around two million years. It takes around this long for the Marañon Valley to split one species into two and for these two species to begin looking different in spite of their ecological similarity.

Next, take a good look below. On the y-axis is a measure of phenotypic differentiation (differentiation in traits that make up their appearance), while on the x-axis is genetic divergence. The expectation is that a certain level of genetic distance — to qualify as different species — will only exist above a certain level of phenotypic differentiation. This is exactly what we see with plumage (A), where the horizontal dotted line marks the cutoff. All the split sister species are above it in black, whereas all the monotypic species, with low genetic and phenotypic divergence, are below it. But we don’t see this in body proportions (B) or in voice (C). This means that either something was wrong with Winger and Bates’s analysis, or that morphology and voice have not changed after speciation.

Why wouldn’t the expected pattern be observed in body shape or voice? The authors suggest that because body proportions tend only to change when adapting to different ecological conditions, it is expected that they would find little change when all their sample species are in the same ecological conditions. Additionally, the authors suggest that the lack of pattern may be an artifact of their analysis, and not a legitimate result.

But what of plumage? A bird’s feathers are a means of visual communication, used to fend off rivals, attract mates, and maintain social groups. They are intimately tied to behavior, and to interactions with other individuals of the same species. What we are seeing is plumage — a trait associated with social behavior like signaling — diverging faster than traits associated with adaptation to new habitats, like body proportions. What does this suggest? I’ll let Winger and Bates answer:

“[O]ur study suggests that social selection plays an important role in driving phenotypic differentiation across the Marañon.”

Yes, sociality may explain why different species start to look different in spite of living in the same habitat. It appears that in the absence of new environmental challenges, changes in birds’ aesthetic preferences can act as an evolutionary force, but this takes time. It takes time — around two million years, to be precise — for mutations to provide new variation in appearance. This variation in appearance may be in male plumage ornaments that attract females in social dominance signals like the black bib on male House Sparrows, or in the bright colors that allow individuals to compete for territories.

All of these traits depend on unique social preferences: females who prefer the slightly-more-extravagant, males that are intimidated by the slightly-more-reddish, juveniles that are more submissive to the more extensive black bib. And these preferences, like human pop culture, seem never to stop changing.

The point is this: in analyzing trait divergence across the Marañon Valley, Winger and Bates have shown that social selection takes around two million years to produce two species from one (when a biogeographical barrier is in place). When populations remain in one piece, kept the same by gene flow, its social preferences also remain in one piece. Regardless, it takes either different resources or geographic isolation to get the process of speciation going. But once it does, social selection may be one mechanism that drives birds to be more different, to be more diverse, and to develop novel social trait preferences.

So in nature, given enough time and the right circumstances, sociality has the power to create new lineages, fill the landscape with more diversity, and, most wonderfully, to enrich the tapestry of life with novel colors and patterns.

And in that way, we see sociality among the diversity of nature mirroring our own.

Or perhaps we are mirroring the rest of the natural world? I’ll leave it to you on that one.

Citations:

Gill, Frank B. “Species taxonomy of birds: Which null hypothesis?.” The Auk 131.2 (2014): 150–161.

Ho, Simon YW, et al. “Biogeographic calibrations for the molecular clock.” Biology letters 11.9 (2015): 20150194.

Winger, Benjamin M., and John M. Bates. “The tempo of trait divergence in geographic isolation: Avian speciation across the Marañon Valley of Peru.” Evolution 69.3 (2015): 772–787.

Barrier Valleys, Trait Divergence, & the Split of Species was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

A major issue in the science of the 21st century is that, well, almost no one reads it. Science, hidden behind a hefty pay wall and big, esoteric words, remains too often in its Ivory Tower of inaccessibility.

I came across a Medium essay that pointedly remarked on this, except that it did so in what has become an even more inaccessible discipline: academic philosophy. See below:

Why We Need “Philosophy Communication”

Two remarks in particular stood out to me. The first is:

“You’re effectively writing to each other and a tiny self-selected choir rather than to the public at large.”

Even in science that has exciting, save-the-world implications— like much of ecology with relation to climate change — there still remains to be a worryingly small audience to your average paper. Some number of scientists might read it, but the more specific the content, the more this number dwindles.

In this way, most publications are indeed, by virtue of their specific content, writing to a tiny, self-selected choir. It is tiny in that the vast majority of literate people will not be reading it — all is relative of course — and it is self-selected in that only people studying this particular system in this particular way to answer these particular questions are meant to read it.

As someone who has only ever perceived science from the lens of a non-scientist, repel the thought that my life’s work will address such a tiny, self-selected audience. I don’t want my life’s work to be measured by academic impact factors alone. As a not-quite-yet-a-scientist, I see science as fascinating, relevant, and even beautiful. But when I’ve attained the knowledge base and technical skill being a 21st century scientist requires, will my work fall into the same folly? Will my work, which has had a great impact on me, and which I believe to be important, be ultimately inaccessible to those upon whom it could have an impact?

Before proceeding any further, what do I mean by this “accessibility,” anyway? I think of accessibility as existing in two forms: intellectual and monetary accessibility. For someone to access the ideas in a scientific paper, the paper much be affordable to attain in the first place, which is to be monetarily accessible. The ideas must also be explained in a way in which the intellect of the reader can understand it, which is to be intellectually accessible. In short, the paper must be affordable and well-written, addressing technicalities without resorting to overly technical vocabulary just to save pages.

Now obviously, there are many scientific disciplines wherein the content really is so technical that most people could not understand it without expansive background. That aside, we currently have an exceedingly bizarre process:

1. Scientists do research and publish the results, written in a way where most people could not understand them, in a journal where most people cannot afford to access them.
2. Science journalists/communicators/writers, who are not themselves scientists and did not actually do the research, do the crucial task of disseminating research to the non-scientist public. Often, the scientist is uninvolved with this, and while most science writers do great work, sometimes results can be distorted, implications can be over- or under-emphasized, and the ‘point’ of the research can be all but lost in unconscious agendas.
3. The public is led to look not to scientists, but to elsewhere in the media to learn about science.

I think many would agree that this disconnect between scientist and science dissemination is not the way we’d like it to be.

So why aren’t the scientists themselves doing that crucial dissemination? It is here that the second remark from “Why We Need Philosophy Communication” comes about:

“[F]unding bodies that provide the lifeblood of academia don’t tend to recognise popular writing in their metrics.”

…i.e., institutions that hire academics often do not incentivize writing specifically for an audience outside of academia. This may or may not be the case for scientists depending on the institution. Either way, scientists often do not have the time to write a blog post, an article for The Atlantic, or The New York Times, in addition to doing research and writing academic papers about it. In the current system, we have a two step process of dissemination: 1) Disseminate to fellow scientists, and 2) Disseminate to the public (if you have time).

The system worth dreaming of, then, is one where scientists write up just one publication that is informative, impactful, and accessible to anyone above a certain level of education (say to all those who have been through college General Biology). We’re not there yet, but many journals are taking steps in that direction. PeerJ and PLOS One only publish open access papers, removing the monetary inaccessibility of typically $35 papers. Science and Nature are making strides in the realm of intellectual accessibility, publishing papers where after the abstract is only the story of the research — from where the researcher picked up their research question to the implications of their results. The complex and technical methods proceed afterward, almost like an appendix only for those who are interested enough to look. By emphasizing that research is often about the telling of a story — a story in which something was learned that has never been learned before — the research paper becomes interesting to anyone curious enough to look.

Until we get to a point where the monetary accessibility of PLOS One and the intellectual accessibility of Nature are combined, and all the problems associated with getting there are resolved, there is still cause for excitement. I came across a gem of a paper recently wherein the current state of ecology was summarized: “Identification of 100 fundamental ecological questions”. Not strictly research, the paper set out instead to review the trials and triumphs of ecology, doing so by identifying 100 ecological questions to which we do not yet have answers. Divided into 7 sections — Evolution & Ecology, Populations, Disease & Micro-Organisms, Communities & Diversity, Ecosystems & Functioning, Human Impacts & Global Change, and Methods — the questions succinctly describe “where we’re at” in ecology, doing so in only 10 pages. It is an admirable example of large-scale, synthesis kind of work made intellectually accessible to any reader. Props to Sutherland et al.

So, for all those interested in accessing ecology “behind the curtain,” look no further than the paper cited below this essay. Below, I have a curated selection of my favorite questions, saving those that were of interest to me, an that could conceivably be examined using birds.

Evolution & Ecology:

• How local is adaptation?
• What are the relative contributions of different levels of selection (gene, individual, group) to life-history evolution and the resulting population dynamics?
• What selective forces cause sex differences in life history and what are their consequences for population dynamics?
• How does phenotypic plasticity influence evolutionary trajectories?

Populations:

• What are the evolutionary and ecological mechanisms that govern species’ range margins?
• How can we upscale detailed processes at the level of individuals into patterns at the population scale?
• How do species and population traits and landscape configuration interact to determine realized dispersal distances?
• How does demographic and spatial structure modify the effects of environmental stochasticity on population dynamics?
• What is the relative importance of direct (consumption, competition) vs. indirect (induced behavioural change) interactions in determining the effect of one species on others?
• How important is individual variation to population, community and ecosystem dynamics?
• What demographic traits determine the resilience of natural populations to disturbance and perturbation?

Disease & Micro-organisms:

• What is the role of parasites and mutualists in generating and maintaining host species diversity?
• How does below-ground biodiversity affect above-ground biodiversity, and vice versa?
• In what ecological settings are parasites key regulators of population dynamics?

Communities & Diversity:

• How can we use species’ traits as proxies to predict trophic interaction strength?
• How well can community properties and responses to environmental change be predicted from the distribution of simple synoptic traits, e.g. body size, leaf area?
• How do species traits influence ecological network structure?
• When, if ever, can the combined effect of many weak interactions, which are difficult to measure, be greater than the few strong ones we can easily measure?
• How widespread and important are indirect interactions (e.g. apparent competition, apparent mutualism) in ecological communities?
• How do spatial and temporal environmental heterogeneity influence diversity at different scales?
• How does species loss affect the extinction risk of the remaining species?
• What is the relative importance of stochastic vs. deterministic processes in controlling diversity and composition of communities, and how does this vary across ecosystem types?
• How do we predict mechanistically how many species can coexist in a given area?
• To what extent is local species composition and diversity controlled by dispersal limitation and the regional species pool?
• What are the contributions of biogeographical factors and evolutionary history in determining present day ecological processes?
• How important are dynamical extinction-recolonization equilibria to the persistence of species assemblages in fragmented landscapes?
• How do resource pulses affect resource use and interactions between organisms?
• How important are rare species in the functioning of ecological communities?
• What is the feedback between diversity and diversification?

Ecosystems & Functioning:

• Which ecosystems are susceptible to showing tipping points and why?
• How can we tell when an ecosystem is near a tipping point?
• Which factors and mechanisms determine the resilience of ecosystems to external perturbations and how do we measure resilience?
• Which ecosystems and what properties are most sensitive to changes in community composition?
• What is the relative contribution of biodiversity at different levels of organization (genes, species richness, species identity, functional identity, functional diversity) to ecosystem functioning?
• How does the structure of ecological interaction networks affect ecosystem functioning and stability?
• To what extent is biotic invasion and native species loss creating ecosystems with altered properties?
• Which, if any, species are functionally redundant in the context of stochastic or directional environmental changes?
• Is hysteresis the exception or the norm in ecological systems?
• Can we predict the responses of ecosystems to environmental change based on the traits of species?

Human Impacts & Global Change:

• What is the role of evolution in recovery from exploitation and responses to other forms of relaxed selection?
• To what extent will climate change uncouple trophic links due to phenological change?
• How do natural communities respond to increased frequencies of extreme weather events predicted under global climate change?
• In the face of rapid environmental change, what determines whether species adapt, shift their ranges or go extinct?
• What determines the rate at which species distributions respond to climate change?
• To what extent can we extrapolate from palaeoecological range shifts to understand 21st-century change?
• Under what circumstances do landscape structures such as corridors and stepping stones play important roles in the distribution and abundance of species?
• To what extent will the breakdown of biogeographical barriers (e.g. the more permanent opening of the Northwest Passage) lead to sustained changes in local diversity?

Methods:

• What unexploited theories used by other disciplines could inform ecology, and vice versa?
• How do we combine multiple scales and types of monitoring (from field to earth observation) to make robust ecological inferences?
• What are the most appropriate baselines for determining the magnitude and direction of ecological changes?

Of course, the issues presented above do not exist in a void. They are mixed in with many other academic issues, including the state of peer review, “open science,” the “publish or perish” culture, and the battle for funding. Complex issues, but all worth solving in the name of understanding this universe of ours.

That’s all for now, folks. Here’s to the open doors.

Citation:

Sutherland, William J., et al. “Identification of 100 fundamental ecological questions.” Journal of Ecology 101.1 (2013): 58–67.

Ecology Behind the Curtain was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

Lately, natural history museums have been under siege. They have been battling to remind society of their importance, to remain funded, and to prove the utility of old, dead things in this very technological 21st century. This war goes on even when so many biological subdisciplines are moving away from natural history and toward theories and models, when fewer people than ever are dreaming of a (dare I say it) romantic career as a taxonomist, and when funding is being increasingly directed elsewhere.

Arguably the biggest victim of this trend, as one might expect, is the small university museum. Universities, for much of their histories, have been central to the exploration of local flora and fauna. State land-grant universities in particular often have surprisingly large collections from a time when more resources (and public interest) were more invested in the natural historian. In times when the natural world was more ‘wild’ and was conceived as more romantic, natural history museums were the epicenter of its exploration by humans. There, exotic findings and novel discoveries were documented, and were revealed for the first time to an eager and curious public. Any university worth its reputation would have housed a natural history collection, even if small. And the big museums — like Chicago’s Field Museum of Natural History, New York City’s American Museum of Natural History, or London’s Natural History Museum — were (and are) flat-out magical.

Since the scientific revolution, great discoveries hail from the halls of natural history museums. Museums are the institutional home for taxonomy, where species are made available for study and conservation by the process naming. This process can often only be done using the veritable database that every museum specimen is, and in spite of some recent calls to use photos or other digital representations instead of museum specimens, this very recent article on the “Omani Owl” demonstrates why. In addition, museums have provided an intellectual milieu for some of history’s most eminent biologists.

Jean Baptiste de Lamarck, famous for the failure of his proposed evolutionary mechanisms, only supported organic evolution as a concept for having had Paris’s National Museum of Natural History at his disposal. While his theories ultimately failed, he was among the first well-known academics to support the theory of organic evolution, an act which had tangibly influenced thinkers in England, including Charles Darwin.

Walter Rothschild drove the cataloguing of life in some of the Earth’s most remote places through the task of filling a museum, one that would become the largest zoological collection ever assembled by a private individual. Now split up, much of this collection — including 280,000 bird specimens — is still driving discovery at the American Museum of Natural History (AMNH).

This collection of 280,000 was fundamental to the success of Ernst Mayr. Mayr was ornithologist who spent much of his career as a curator and biogeographer at AMNH, describing 26 new species himself and cataloging many more in three detailed volumes (“New Species of Birds Described from 1938 to 1941,” “New species of birds described from 1941 to 1955,” & “New species of birds described from 1956 to 1965”). He would later go on to be an architect of the synthesis between genetics and evolutionary theory, along with developing the Biological Species Concept, modernizing avian systematics, popularizing evolutionary theory, and publishing 25 books and more than 300 publications. One must wonder what Mayr would have been without the American Museum of Natural History.

Local Museums, like the Bell Museum of Natural History here in Minnesota, were and continue to be the source of new insights about species in Minnesota and beyond. When the University of Minnesota houses such a museum, researchers here can remain at their institution to use the collections daily for teaching and learning. If this museum were closed, sold, or otherwise shipped off into a warehouse as some cost-cutting universities have done, researchers would have to travel to the aforementioned larger museums to do museum-related work. When researchers have to travel far away to places like the Field Museum or AMNH, places that have their own challenges, their capacity for spontaneous “aha!” moments, for the construction of novel databases, for honing forward-thinking museum-based methods, and especially for teaching, is severely reduced.

Without museum collections within universities, we have another example of where institutions are substituting the artificial — an image file, a digital sound recording, a video — for the real thing — a museum specimen.

We lose something very tangible when such real things are not readily accessible to the thinkers, learners, and dreamers found in universities.

Perhaps this is because society has lost interest in the Earth, in the rich diversity of its species, in the complex and mysterious ways living things interact, and/or in our place in nature. To me, this seems exceedingly unlikely. Rather than the loss of funding and support for museums reflecting society’s interests, I think they reflect a loss of exposure. Having entered a technological age when nothing is as engaging as this screen right in front of me, we have also entered a negative feedback loop with museums. When fewer people visit museums to wonder at the diversity and beauty of the natural world, fewer people receive recommendations to go from their friends.

It is often said that the best way to get people to value the natural world is to expose them to it. I believe this to be the case with museums too. When you take away museum collections from university researchers, future researchers will never know what they’re missing, and will certainly have no reason to support the preservation of costly museums. Students, having never seen and learned from a museum specimen, will never miss their presence in the college classroom.

We cannot miss what we have never experienced,

and if we keep closing museum collections in universities, us collection-lovers may have to face the fact that nobody else would lift a finger to support their preservation.

So, do people care even now? Have we passed this time when too few people have benefitted from, wondered at, and had research careers catalyzed my museum collections?

Thankfully, the answer is a resounding, “No!”

Museums, their collections, taxonomy, and natural history have been receiving a lot of hype recently — enough hype to bring out my optimism. Take a look at some of what has been said:

Ed Yong, in The Atlantic, wrote“Natural History Museums Are Teeming With Undiscovered Species,” to reconnect museums with the romance of exploration. The piece features an interview with Evon Hekkala, reminding us that the “average specimen languishes for 21 years before it’s formally described,” and casts collections in such a light as this:

“It’s easy to view such collections as soulless stashes, examples of humanity’s hoarding instinct unleashed upon the natural world, turning vibrant menageries into dead zoos, and living, breathing, mating, hunting, fighting creatures into mere specimens, dissembled and dissected, posed in dioramas, pinned in drawers, crammed into cabinets, and stuffed into jars. But to Hekkala and many other scientists, these hoards are full of riches still. They are time capsules that contain records of past ecosystems that are rapidly changing or disappearing. They are archives that provide clues about raging epidemics, environmental pollution, and hidden extinctions. And they are full of unknown species.”

What dreaming child would not be inspired by such a description? For many of us — who would be considered a choir to whom Yong is inadvertently preaching — this quotation brings up those first moments of childlike wonder at museum specimens, be they zoological, botanical, geological, or paleontological. Chicago’s Field Museum created a beautiful piece to encapsulate this sentiment after the tragic passing of eminent mammalogist Bill Stanley. I encourage you to give it a watch:

In Wired, Craig McClain delivers a powerful op-ed about the irony of defunding museums when we face a biodiversity crisis:

“Species are going extinct at rates equaled only five times in the history of life. But the biodiversity crisis we are currently encountering isn’t just a loss of species, it’s also a loss of knowledge regarding them.”

In “The Mass Extinction of Scientists Who Study Species,” we encounter a call for the survival by those who are often housed in — and paid by — natural history museums: taxonomists. As of 2002, approximately 6,000 individuals, worldwide work explicitly as taxonomists. It has been said that doubling this number “could move the global biodiversity survey to near completion within a single human generation,” a feat that would surely advance our capacity to balance humanity with other species in this age of climate change. Instead, one can only assume that the hallmark science of museums, taxonomy, has become less populated since then. There are many groups of organisms whom no taxonomists are classifying, and even well-known groups remain understudied. McClain recounts that,

“nematodes represent more than 28,000 described species of freshwater, marine, terrestrial and parasitic roundworms. On the seafloor they account for 85 to 95 percent of all organisms. But a new study found the number of scientific papers describing new nematode species is half of what it was a decade ago, and a third of the decade before that. Anywhere between 10,000 and 100,000 species remain undescribed.”

Citing some reasons for why this may be occurring, McClain’s timely warning, one we should heed more enthusiastically in this time of climate change, is this:

“[P]rogress in biology as whole may be impeded if we lose taxonomy. The problem we face is a loss of knowledge not yet recorded in the scientific literature. In our technological efforts to concentrate our biodiversity knowledge, we may be rendering a field and body of knowledge obsolete. And in the process, we may be undermining our own efforts to protect biodiversity.”

In “Ghosts and tiny treasures,” Brian Pfeiffer reminds readers of the many species who, thanks to museums, are forever extinct, but never to be forgotten. As one answer to the question of whether we’ve reached that critical time when too few people care about museums, taxonomy, and natural history to save them, Pfeiffer argues that,

“Despite the distractions, yes, we do care. That is genuine. We care about big woodpeckers and giant pandas. We care about whales and baby seals. We cared about Cecil the lion — but for all the wrong reasons. Maybe the gratuitous killing of one lion in Zimbabwe did the world — and the lions — some good. That’s not yet clear to me. But is this what it takes? A dead lion with a name, a Minnesota dentist who pulled the trigger, and the rise of an internet lynch mob? Is this how we take action and measure our victories?”

Citing the many vices of the 21st century as a cause for apathy, Pfeiffer characterizes it with the cynicism that many of us probably share:

“Take your pick from actual chronic or acute causes of extinction or extirpation: invasive plants, pesticides, climate change, our own population bomb. How hard we work to tell the world about those actual threats. But a guy shoots a lion, and we have a target for our online opprobrium — a target other than us. So instead of reasoned action to deal with genuine threats, the masses grab their torches and pitchforks (Twitter and Facebook) and storm ‘the cloud’ demanding blood as vengeance for Cecil. Maybe they get some. Maybe not. And then the masses go back to watching cat videos or a rat carrying pizza into the subway; we go back to warming the planet, drinking factory coffee, and spraying chemicals on our lawns.”

Worse, so many “species vanish with only limited public awareness and few advocates working on their behalf,” functions that museums and those that worked in them hold by default.

His message of hope is the following:

“We can discover more. The great unknown at our feet is a remedy for the extinction of experience. Those actual encounters with the wild outside, no matter how near or how common, help us relate to the wild far away, no matter how remote or rare.”

In Nature, Christopher Kemp wrote, “Museums: The endangered dead,” focusing in on museum collections as an epicenter for new species discovery, and a necessity in the age of climate change. Reverberating a similar message to Yong’s, Kemp states that,

“[R]esearchers today find many more novel animals and plants by sifting through decades-old specimens than they do by surveying tropical forests and remote landscapes.”

And yet, budget cuts have produced some remarkably short-sighted reductions in the people that do such sifting:

“The Field Museum in Chicago, Illinois, had 39 curators in 2001. Today, there are just 21. At present, there is no curator of fishes — an enormously diverse class of animal. Neither The Field Museum nor the AMNH — which hold two of the largest collections in the world — has a lepidopterist on staff, even though both collections contain hundreds of thousands of butterfly and moth specimens. Similarly, the National Museum of Natural History has seen a steady drop in the number of curators — from a high of 122 in 1993 to a low of 81 last year.”

Why do we need these people? In order to conserve rare or endangered species, or to understand the dynamics of ecosystems, we need to have a name on these species in the first place. As humans, everything starts with the name, the semantic creation of something we can study, and something we can protect. One cannot publish papers on the nameless. And one cannot conduct the naming of things, in biology, without taxonomists. Without museum specimens, taxonomists could not hope to have the insight necessary to describe new species.

Perhaps even more notably, museums house the development of new biological techniques, allowing researchers to answer new questions in new ways using old information. This process then feeds back into conservation and taxonomy like so:

“DNA sequencing helped Hanken to describe and name 14 species, all of which have been declared endangered by the International Union for Conservation of Nature. Usually, says Hanken, once genetic data have identified a species, he can find subtle features — in the skeleton, coloration or body size — that allow him to tell the animals apart.”

One cannot speak of efforts to communicate the value of museums without mentioning Emilie Graslie, whose work you can find on The BrainScoop. Below, Graslie argues for the value of museums, in spite of their initial incomprehensibility:

Also worth noting is this extraordinarily comprehensive paper, “The Value of Museum Collections for Research and Society”, which does are far better job of arguing for museums than I do, and the Ecological Society of America’s recent efforts to facilitate returning more interest to Natural History.

So, there are loud voices calling out in the name of museums, taxonomy, and natural history. But has anything actually happened? Has the noise all been for naught?

In many places, the answer to this question is still uncertain. But recently, Minnesota’s Bell Museum of Natural History released its plans for a new building, and has filled me with an optimism compelling enough to write this essay.

(Unfamiliar with the Bell Museum? Need an intro to why it matters? Check out this YouTube playlist.)

As if in response to all the challenges we saw above, the University of Minnesota is investing in natural history enough to provide it a new home on campus, one that aims to engage the public more in natural history. In other words, there remain people out there to whom engaging the public with natural history is a priority. While this update for the public may not mean any direct benefits for the researchers that use the Bell’s collections, one thing is certain:

More public engagement in a fantastic new museum translates to inspiring more future scientists to query this mysterious universe we’re a part of. It means more people who value museums, their collections, and the kind of work they catalyze. It means more people who care about biodiversity, and have the resources to understand and protect it.

The state of museums may be dire now; the state of biodiversity is certainly dire now. And while this Bell Museum update doesn’t spell victory for all natural history museums against the forces of budget-cutting, it does give us something to smile about. Even a few people who care, as all the articles listed above show, can matter a great deal.

Here’s to one triumph, museum geeks, and hopefully to many more.

Works quoted, embedded, or otherwise linked:

Wei-Haas, Maya. “The Story Behind Those Jaw-Dropping Photos Of The Collections At The Natural History Museum”. Smithsonian. N. p., 2016. Web. 30 Apr. 2016.

Meyer, Axel. “On The Importance Of Being Ernst Mayr”. PLoS Biology 3.5 (2005): e152. Web. 30 Apr. 2016.

Yong, Ed. “Natural History Museums Are Teeming With Undiscovered Species”. The Atlantic. N. p., 2016. Web. 30 Apr. 2016.

“The Switch: A Bill Stanley Story”. YouTube. N. p., 2016. Web. 30 Apr. 2016.

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“Where’d You Get All Those Dead Animals?”. YouTube. N. p., 2016. Web. 30 Apr. 2016.

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Natural History Museums: A Message of Optimism was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

This sort of writing is what I would call a ‘heuristic essay’. Its purpose is to crystallize thoughts — thoughts that are part of my learning process — through externalization. In other words, this essay is the product of my use of writing to clarify. Its aim is not to convince, not to inspire, but rather to shed light on principles which may remain otherwise veiled by ambiguity to most readers. I hope that in doing this sort of writing for myself, I can add to the richness of your own learning experience. More than anything else, the message of these essays is to focus on learning instead of knowing. Why? Because what we still have to learn has far more profound implications in our lives that what we know. With that, I bid you read on, all ye curious…

In this big, wide world of ours, there exists an essential conflict of interest. Humanity, dreaming of its own high moral pedestal, a dream of ascendancy like that of medal-winning Olympians, defines its own specialness in a way that also destroys it. Humanity is, like the many Greek heroes that represent it, a victim of its own hubris. Believing itself a master, deluded by an illusion of control, humanity takes and takes, leaving little behind but degraded wastelands and decrepit urban sprawl.

Through history, we humans have existed on one or another side of the fence: a fence of industry. Before the industrial revolution (the first one), we lived in what is often depicted as a harmony with nature, a past so oft-romanticized by poets and essayists. Regardless of the validity of this perception, it remains true that people lived without a stark conceptual barrier between the natural and the artificial world. Inexorably immersed in nature, escape to a modern city would not be an escape from a harsh natural setting, but rather a passage into a hostile and unknown world. Part of the fabric of nature, life was a little closer to, a little deeper into what is called nature today. Even while humans plunged species into extinction and degraded ecosystems, perception of humanity’s relationship to nature was that humanity was among nature, not beyond it.

And then, swept up by the irons of industry, cities bloated and smoke billowed, transforming the world into a technological labyrinth utterly unforeseen. Now, immersed in concrete and silicon, we have a 20/20 hindsight, retrospectively aware of just how influential this fence was. To put it simplistically, we once lived in harmony with nature, but when science and technology got too zealous, we entered an age when nature become a resource, not a home.

Of course, we know that these lifestyles were not anchored in the attitudes of the time. For centuries before the industrial revolution, many Christian doctrine dictated that nature was a masterfully created chain of being for the use of man. Even when we were in no position to conquer nature, many still believed in our ascendancy above it. It was this deeply held impression of humanity’s superiority, of nature’s intended use by humanity, that blossomed into the political and economic foundations of industry.

In spite of this prevailing doctrine, a feeling of deep association with nature is comparatively ancient, a tradition of human nature harkening back to our tribal, nomadic origins. Among Europe’s many tribes, Christian doctrine largely replaced Pagan systems, systems that often categorized humans among nature’s many other species. Europe’s Pagan cultures held it as self-evident that we lived in harmony with nature. In this way, especially when we consider the ancient pantheistic traditions of Eastern religions as well, defining ourselves as part of nature is the historic (and prehistoric) norm, merely interrupted for a short stretch of centuries by anthropocentric Christianity.

Having lived through two centuries of anthropocentric industrialism, association with nature has at last returned to the fore again. After the scientific excitement set off by the Enlightenment — an excitement that could be called naïve — technological growth exploded, and fueled the forge of industrial revolution. But after long enough, Western societies looked out at what they had done. Dismayed by urban sprawl, by slums, by billowing smokestacks and coal-fire smog, they came to the terrible realization that they had created a monster. The West had transformed into a toxic beast, one whose appetite could never be satiated. Fed by theories of capitalism, imperialism, and racism, the industrial world infected the entire planet, enveloping it in technological development and profiteering.

But we could never quite return to the circumstances of the past. Most technologists couldn’t dream of the simple farming life in Selborne’s famous hills. Most scientists couldn’t fathom of a career of arbitrary writing as a cog in the monastic tradition. Most philosophers couldn’t swallow a career interested only in utilitarianism, forsaking their delightful forays into metaphysics and existentialism. No, ethics are too different, as are our understandings of the universe.

In all, one essential understanding has changed: our place in that universe. After the industrial revolution, ashamed of the destitution science and technology had wrought, something in our lifestyle had to change, and that change had to be driven by ideology. The belief that nature was a resource had gone too far. Too many people lived in poverty. Too many cultures had been smothered by imperialism. Too many swathes of grand ole’ ‘greenness’ had been lost forever. No, what we needed back in our lives was romance, and in this instance in history, that romance was needed in science.

Scientists were becoming increasingly isolated from the public. Retreating into their labs with their instruments and their reductionism, scientists occupied an ivory tower of knowledge whose walls increasingly thickened with inaccessibility. Science was no longer open to any layperson; it had come of age, and with this age, came its pretenses.

Science had to backtrack. Science had to become romantic without becoming unscientific. Its enterprises, in other words, had to reconnect with nature, inspiring newfound connection therewith, a message to be shared with anyone.

But this shift in paradigms required an abandonment of science’s mechanistic traditions. Rather than study parts of nature, science needed instead to study the romantic whole, the all. Instead of reducing nature to a sum of parts to be used by man, science had to view it holistically. People didn’t want to be cogs in a mechanistic world; they wanted to be participants in a living world. They craved connection to something greater than themselves, a craving we still cherish today.

Enter ecology. Aiming to feed this desire for connection and romance, naturalists returned to the field to study behaviors and interactions. Instead of classifying nature as parts, early ecologists understood nature through its grand workings. By looking at how different organisms interact with each other and their environment, we began seeing emergent properties of nature that were invisible to us before. These emergent properties depict life as more than a sum of its parts, and by fitting into it, we become more than mechanisms. Ecology, in cautioning against excessive reductionism, is the wholeness we craved through the empty mechanistic spasm that initiated the industrial revolution.

But for all intents and purposes, ecology’s essential philosophy is but a proposition. Humans are defined by their peculiar ability to believe whatever they choose, regardless of evidence. And for some interests, believing that nature is a resource for humans is…how shall we put it…more advantageous? But thanks to the romantic backlash against the industrial revolution, we now have a confident voice from the other side of the fence, from a side where we feel more whole and at peace, where we, as human beings, are not reducible to mechanisms. Regardless of belief in supernatural souls or vitalistic life forces, we are more than cogs in an industrial machine.

In proposing this view, ecology was always poised to become one of science’s most influential fields. It tempered industrialism, lent skepticism to imperialism, and now speaks with force on the issue of climate change. And in understanding nature as a whole, ecology is first in line to inform movements toward sustainability.

It is for this reason that ecology has become so much more than a science. Its penumbra of influence allows such terms as ‘ecological thought’, ‘deep ecology’, ‘ecological philosophy’, and even ‘ecological politics’. With it comes an inherent ethic, a philosophical element sorely missing from most other sciences. And with this philosophical element, ecology has the power to pervade politics, economics (a closely linked field at its inception), and even religion.

With such philosophical purchase, ecologists are much more than scientists, and while taking up arms of influence depends on the zeal of the rifleman, a degree in ecology is as much a degree in philosophy and ethics as it is a degree in science.

So come, ye fellow communicators! Let us dance to that harmony of life in our woodland field stations, and toast the wholeness of nature! We must be sure to share the fruits of our celebrations with all others, from the most diehard, reactionary capitalist to the most aloof and nomadic hippie.

All are friends in this orchestra of life. We must not mistake dissident chords for disunity, for if we do, we lose touch with that sense of oneness that drives us to nature in the first place.

Thoughts? Questions? Critiques? Speak up! A wise man once said we should try to be wrong as fast as possible. Sharing your perspective will only help my learning process and that of anyone who reads this.

Many thanks to my editor Susan Jones, a historian of science at University of Minnesota, whose critiques elevated the sophistication of this essay, and also of my historical thinking in general.

On the History of Ecology was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.

Oh how good it would be, we humans think, to have simple solutions to that grand challenge we call climate change. How easy it would be, to rally the unified, international response it necessitates. In one fell swoop, we could make immense progress in securing the future of humanity on this planet in spite of its past pitfalls.

But alas, we do not live in that world.

In exploring the natural world, we see that many animals face a similarly complex problem to solve: in climate change, they face rapid change. After just two centuries — a veritable blink of an eye to the time scales most evolution occurs on — of human influence, we live in a world where global temperatures have risen an average of 1.4 degrees Fahrenheit, where the yearly minimum of Arctic sea ice has shrunk 13.3% percent per decade, where CO2 levels have reached a 650,000-year peak.

So often we forget that this ‘we’ includes more than just humans. Humans share the earth with a profusion of life, most of which we could neither name nor describe. On this spaceship we call Earth, we humans are participants in an ancient natural system, one which prospered for billions of years before us, and could conceivably do the same after our disappearance.

Thus is the reality of life, as so eloquently forewarned by Jurassic Park’s Ian Malcolm: “Life will find a way.”

But while life itself is likely to prosper for billions of years, each species exists in a precarious balance, struggling from the time of its divergence to its eventual extinction. Through even greater toil must the individual struggle, competing with others for space and resources. How does climate change play into this struggle? By inducing climate change, we are changing the environment faster than the time evolution needs to produce adaptations.

Indeed, two centuries is not nearly enough time to allow species to adapt to climate change. It’s not enough time for montane species to search out new mountaintops as warmer temperatures — and disease-carrying mosquitoes — creep uphill. It’s not enough time for coral species to cope with increasingly acidic oceans. It’s not enough time for Polar Bears to adapt to less icy environments and the different prey species they support.

It simply is not enough.

So for those species that are adapting, what sort of adaptation are we talking about? When there simply isn’t enough time for natural selection to guide adaptations, we must consider a different form of adaptation altogether: behavioral adaptation.

And here we enter one of the most fascinating interfaces of evolution and ecology, a realm where the capacity to respond to challenges in many ways is the adaptation. When new, fast moving challenges present themselves, those species that keep doing the same thing will not be able to cope. But when sudden challenges are taken on by behaviorally flexible species, their capacity to respond in many ways — or even creatively — is the greatest of advantages. To observe the environment and adapt within the course of a lifetime is to ensure a baseline preparedness for unknown challenges.

Enter Poecile palustris — the Marsh Tit — a delightful little European relative of North America’s chickadees. In pondering how species respond to climate change, Poecile palustris helps make an essential distinction. In responding to rapid environmental change, two processes can increase species’ ability to cope: microevolutionary change and individual plasticity.

Microevolutionary change is change in a species through time, where some mutations occur in a population that are advantageous. Over time, these advantageous mutations become more common, and as such, the population is said to be adapting. This is true adaptation: it occurs at the level of the population, and never within an individual’s lifetime. Why? Once an individual is conceived in a parent, its genome will never change.

Individual plasticity, on the other hand, is all about change within a lifetime. Not true adaptation, individual plasticity entails behavioral and/or physiological flexibility. In this way, when you are having a stressfully busy day, the sort where plans are constantly changing and you just have to “go with the flow,” you are being behaviorally plastic. The only difference is that you’re not doing it for survival, not matter how much it may seem like it.

Like many other members of the family Paridae, Marsh Tits stay in the same place throughout the year, making the same individuals easy to find within and between years. All that’s needed, then, to draw conclusions about individual plasticity, is long-term tracking and a changing environment.

Luckily, the latter is inescapable, and the former can be found in Poland’s Białowieża National Park, where long-term studies have been conducted on Marsh Tits for more than 40 years.

Why, in the age of climate change, does individual plasticity matter? First, to do effective conservation on declining species, it is necessary to know whether they cope with environmental change through microevolutionary change or through individual plasticity. In other words, does ‘adaptation’ (a term used liberally here) occur between generations, or within the individual’s lifetime? Second, it is of paramount importance to know the limits of individual plasticity. Inherently, a behaviorally flexible species will be able to cope faster with climate change. Why? Individuals can each cope within the timescale of their own lives, rather than change happening only between the generations. But even the flexibility has limits, with some species — and some individuals — being intrinsically more plastic than others.

In short, it is essential to know whether individual plasticity is the solution used by a given species, and if it is, it is then essential to know that plasticity’s limit. Why? That limit is the tipping point, beyond which that species cannot cope with faster environmental change.

So how do Marsh Tits cope with environmental change? This is exactly the question Tomasz Wesołowski et al. set out to answer with a paper published this past July in the Journal of Avian Biology.

To understand behavioral flexibility, ornithologists often look at a bird’s annual schedule, or phenology, to see how it changes the timing of major life events like, say, breeding. Because breeding costs so much time and energy, and is responsible for everything on which natural selection acts, birds must time it perfectly. They must only start the breeding season when the weather is palatable, when there is enough food of the right kinds, when enough nest locations are available, and when predators aren’t too prevalent. Because there is so much pressure to optimize this timing, there are few better life events to study for solutions to environmental change.

Between 2013 and 2014, the spring weather conditions in Białowieża National Park ranged across the gamut. In late March in 2013, temperatures remained cold at -5.1 degrees C (22.8 degrees F), whereas at the same time in 2014, temperatures warmed up to 7.1 degrees C (44.78 degrees F). We have our species, and we have our environmental change.

With unforeseen flexibility, the Marsh Tits shifted the start of their breeding season (egg-laying) by up to 23 days, all in an attempt to strike the perfect balance of weather and resources. While many species — especially migratory species — have a rigid annual schedule, Marsh Tits had the individual plasticity to shift the onset of their breeding season by almost a month. Above all else, Marsh Tits are remarkably plastic. Between 2013 and 2014, the sixteen tracked individuals made these drastic shifts as a response to the environmental challenges they faced. And because it was within the course of their lifetimes, it can be extrapolated that Marsh Tits in general rely more on individual plasticity to cope with environmental challenges than they do on microevolutionary change.

Even more remarkable is that the sixteen Marsh Tits in this one location shifted their breeding start date as much as had ever been recorded throughout the species’ entire latitudinal range. This means that if one were to compare egg-laying dates between a Marsh Tit in Sweden to a Marsh Tit in Italy, the variation would be about the same: a median difference of 20 days.

If individual Marsh Tits in one location are as flexible as the entire species, then they seem remarkably well-prepared for rapid climate change. When individuals of a species are relatively “set in their ways” in regards to when they breed, it could take thousands or even millions of years for evolution to adapt them to a changed environment. Not so with Marsh Tits. Because they are so flexible, individuals of this species could make the same amount of change within a lifetime. And that, with all our grim projections, is a powerful advantage indeed.

So far, it appears that Białowieża National Park’s radical temperature shift between 2013 and ‘14 are not due to climate change. Even if they were, Marsh Tits would be ready. This advantage of flexibility, the authors say, would “suffice to adjust birds breeding times to the forecasted climate changes.”

So what we have here is a remarkably flexible species in regards to egg-laying date. Even more importantly, we have found an example of where life has found a way, where organisms have escaped the bounds of evolutionary time to cope with faster environmental challenges.

While these findings make us optimistic about the prospects of Marsh Tits in the face of climate change, we must remember that not all species are sedentary, arboreal songbirds. Across the myriad of organisms on our planet, we have equally diverse levels of plasticity in coping with change. In some species, time between generations is so short that there is no point in plasticity, as microevolutionary change is enough to keep up with environmental change. In others, time between generations is so great that plasticity is the only way individuals could cope with seasonal, annual, or even decadal environmental change.

But at least in the animal world, it appears that most species are not quite plastic enough to keep up with climate change. Most species — including birds — appear not to be flexible enough to adapt to rapid, human-induced change. Tropical species, for example, who haven’t evolved under inherently variable, seasonal conditions, are among the most limited in capacity to change with the environment.

Even more frightening is how few species’ individual plasticity have been studied. How could we possibly understand how climate change will affect a given species if we don’t know how quickly it can adapt? Even if we did know that species’ plasticity, we aren’t even close to understanding just what that plasticity means. In the case of Marsh Tit, “How do Marsh Tits know the right time to lay eggs?”, “What physiological processes allow this flexible timing?”, “What is the genetic component to this individual plasticity?”, and “How is individual plasticity maintained at the population level?” are questions to which there are no answers…yet.

We do have one answer: Marsh Tits are remarkably flexible. A single female can bide her sweet time until the right time comes to lay eggs, not to mention her uncanny ability to recognize this ‘right time’. But the mechanisms behind this flexibility? We have no idea.

When we look in nature, we do find unique solutions to that grand challenge we call climate change. But what we’ve found so far is only the beginning; while we know that some species can adapt, we know not how. Though we know some species can’t adapt, we know not why. To understand the reality of how climate change affects this little planet of ours, these kinds of questions need answers.

Perhaps somewhere in coming to understand how other species cope with climate change, we’ll find some solutions for our own species. With a deeper understanding of nature’s workings, we can better understand how to balance our species with that myriad of others.

After all, what better place to learn lessons of self-betterment than from that inexorable march of adaptation from whence we came?

Citation:

Wesołowski, T., Cholewa, M., Hebda, G., Maziarz, M., & Rowiński, P. (2015). Immense plasticity of timing of breeding in a sedentary forest passerine, Poecile palustris. Journal of Avian Biology. Retrieved October 22, 2015.

Of Birds, Behavior, & Climate Change was originally published in SPECIOSE on Medium, where people are continuing the conversation by highlighting and responding to this story.