Biodiversity

​Biodiversity, short for biological diversity, is the variety of organisms in a given area, the genetic variation within a population, the variety of species in a community, or the variety of communities in an ecosystem.

​Bio means life
Diversity refers to differences or variety

​Biodiversity can be studied and described at three main levels:

• Species diversity

• Ecosystem diversity

• Genetic diversity

Genetic diversity refers to all the different genes contained within all members of a population. 

A gene is a segment of DNA that is located in a chromosome and that codes for a specific hereditary trait.

Genetic variation increases the chances that some members of the population may survive environmental pressures or changes.


Small and isolated populations are less likely to survive such pressures.

​-OR-

All the differences between populations of species, as well as between different species. 

​The number of different species and the relative abundance of individuals within each of those species in a given area

How evenly individuals are distributed among each species

​Species Evenness

The number of different species found in an area

​Species Richness

Ecosystem diversity refers to the variety of habitats, communities, and ecological processes within and between ecosystems.

• destruction of habitats

• introduction of nonnative species

• pollution

• overharvesting

​Destruction of habitats is the most severe threat to biodiversity

When there are no longer any living members of a species, family, or other group, that organism is considered extinct.

The extinction of many species in a relatively short period of time is called a mass extinction.

Earth has experienced several mass extinctions (probably caused by a global changes in climate) and
it takes millions of years for biodiversity to rebound.

​Dodo bird

A species that has been identified to be likely to become endangered in the foreseeable future. 

​Threatened Species

A species that has been identified to be in danger of extinction throughout all or a significant part of its range, and that is thus under protection by regulations or conservation measures. 

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​Endangered Species

​Shenandoah Salamander

​Piping Plover

• An exotic species is a species that is not native to a particular region.  

​Exotic Species

​Exotic species can threaten native species that have no natural defenses against them.

​Lionfish & Rapa whelk

• An endemic species is a species that is native to a particular place and that is found only there.

​Endemic Species

• ​Ecologists often use the numbers of endemic species of plants as an indicator of overall biodiversity because plants form the basis of ecosystems on land.

• An important feature of areas of the world that contain greater diversity of species is that they have a large portion of endemic species.

​Virginia opossum

• Biodiversity hotspots include mostly tropical rainforests, coastal areas, and islands. 

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• Certain areas of the planet, such as tropical rainforests, contain an extraordinary variety of species. 

• These areas are called biodiversity hotspots, and are usually the most threatened areas of high species diversity on Earth.

Terrestrial Hotspot Map

Species that are critical to the functioning of the ecosystem in which it lives because it affects the survival and abundance of many other species in the community.

​Keystone Species

Environmentally sensitive species that serve as early warnings that a community or ecosystem is being degraded.

​Indicator Species