Science Tutorials
Biodiversity
The Living World: Ecosystems and Biodiversity Part 7
Biodiversity
Biodiversity is used to describe the number and variety of organisms found within a specified geographic region, or ecosystem. It also refers to the variability among living organisms, including the variability within and between species and within and between ecosystems. When talking about the biodiversity of an area, we must specify the aspect of biodiversity that we are describing, or else the term is too vague to be comprehensible.
Species richness refers to the number of different species found in an ecosystem.
Biodiversity in an ecosystem is a good thing, usually. The more biodiversity in a certain species within an ecosystem, the larger and more diverse the species’ gene pool, the greater its chance of adaptation and survival.
An Ecosystem is Threatened or a Habitat is Lost
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This habitat loss tends to lead to a loss of specialist species, which then can lead to a loss of generalist species. Additionally, species that require large territories tend to suffer, and their numbers are reduced. When a large population is lost, this leads to a bottleneck, which can reduce genetic diversity within the species. A disturbance in an ecosystem will affect the total biomass, species richness, and net productivity over time. Ecosystems with larger numbers of species (species richness) tend to recover more easily from disruptions.
The more genetically diverse a given population is, the better it can cope with an environmental disturbance. Ecosystems and biodiversity are inextricably linked.
Law of Tolerance
The Law of Tolerance describes the degree to which living organisms are capable of tolerating changes in their environment. Living organisms exhibit a range of tolerance, and even individuals within a population tolerate changes to their environment differently. This concept is the basis for natural selection, which drive evolution.
Law of Minimum
The Law of Minimum states that living organisms will continue to live, consuming available materials until the supply of these materials is exhausted.
Theory of Island Biogeography
This is a special case of the interrelatedness of habitat, biodiversity, and adaptation. This is a field that studies species richness and diversification in isolated communities: oceanic islands, and also other isolated ecosystems, such as mountain peaks, oases, seamounts, and fragments of habitat separated by human development. The number of species found on an island or in an isolated area is determined by two factors: immigration and extinction. Since islands are often colonized by new species arriving from elsewhere, immigration is a main factor. Once established on an island or in an isolated ecosystem, many species evolve to become specialists as an adaptation to the limited resources available. Immigration becomes a factor again when invasive species arrive, since the typically-generalist invasives may outcompete the native specialists and threaten their long-term survival.
References and Further Reading
