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Learn about the number, distribution, and importance of species diversity on Earth. Explore the challenges and methods of cataloging and studying the biodiversity of life.
- Genetic Diversity
Loss of wild species related to a crop will mean the loss of...
- Ecosystem Diversity
Food Production and Ecosystem Services; References;...
- Preserving Biodiversity
The number of species of carrion eaters has increased...
- 6: Species Diversity
Duke University. Strictly speaking, species diversity is the...
- Genetic Diversity
Feb 28, 2024 · Species diversity is the number and relative abundance of species in a particular area. Learn about its components, levels, importance, and threats, and see examples of species diversity in different ecosystems.
Species diversity is the number of different species in a given community or dataset. Learn how to calculate it using various diversity indices, such as species richness, Shannon index, Simpson index and Gini-Simpson index, and how to account for sampling considerations and trends.
- Overview
- Measuring biodiversity
- Counting species
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Biodiversity, also called biological diversity, is the variety of life found in a place on Earth or, often, the total variety of life on Earth. A common measure of this variety, called species richness, is the count of species in an area. Biodiversity also encompasses the genetic variety within each species and the variety of ecosystems that species create.
What are the ways to measure biodiversity?
Examining counts of species is the most common method used to compare the biodiversity of various places. A second way to weigh species biodiversity is to recognize the unique biodiversity of those habitats that contain few but unusual species, such as volcanoes, thermal vents, and hot springs. In practice, biodiversity is weighted differently for different species.
What has led to the decline in biodiversity in recent times?
The pace of decline and extinctions in biodiversity has risen dramatically over the last century, as the effects of climate change increased and human activities such as agriculture, fishing, and hunting continued to encroach into more remote natural areas all over the world.
Which year was named the International Year of Biodiversity?
Although examining counts of species is perhaps the most common method used to compare the biodiversity of various places, in practice biodiversity is weighted differently for different species, the reason being that some species are deemed more valuable or more interesting than others. One way this “value” or “interest” is assessed is by examining the diversity that exists above the species level, in the genera, families, orders, classes, and phyla to which species belong (see taxonomy). For example, the count of animal species that live on land is much higher than the count of those that live in the oceans because there are huge numbers of terrestrial insect species; insects comprise many orders and families, and they constitute the largest class of arthropods, which themselves constitute the largest animal phylum. In contrast, there are fewer animal phyla in terrestrial environments than in the oceans. No animal phylum is restricted to the land, but brachiopods (see lamp shell), pogonophorans (see beardworm), and other animal phyla occur exclusively or predominantly in marine habitats.
Some species have no close relatives and exist alone in their genus, whereas others occur in genera made up of hundreds of species. Given this, one can ask whether it is a species belonging to the former or latter category that is more important. On one hand, a taxonomically distinct species—the only one in its genus or family, for example—may be more likely to be distinct biochemically and so be a valuable source for medicines simply because there is nothing else quite like it. On the other hand, although the only species in a genus carries more genetic novelty, a species belonging to a large genus might possess something of the evolutionary vitality that has led its genus to be so diverse.
A second way to weight species biodiversity is to recognize the unique biodiversity of those environments that contain few species but unusual ones. Dramatic examples come from extreme environments such as the summits of active Antarctic volcanoes (e.g., Mt. Erebus [see Ross Island] and Mt. Melbourne in the Ross Sea region), hot springs (e.g., Yellowstone National Park in the western United States), or deep-sea hydrothermal vents (see marine ecosystem: Organisms of the deep-sea vents). The numbers of species found in these places may be smaller than almost anywhere else, yet the species are quite distinctive. One such species is the bacterium Thermus aquaticus, found in the hot springs of Yellowstone. From this organism was isolated Taq polymerase, a heat-resistant enzyme crucial for a DNA-amplification technique widely used in research and medical diagnostics (see polymerase chain reaction).
More generally, areas differ in the biodiversity of species found only there. Species having relatively small ranges are called endemic species. On remote oceanic islands, almost all the native species are endemic. The Hawaiian Islands, for example, have about 1,000 plant species, a small number compared with those at the same latitude in continental Central America. Almost all the Hawaiian species, however, are found only there, whereas the species on continents may be much more widespread. Endemic species are much more vulnerable to human activity than are more widely distributed species, because it is easier to destroy all the habitat in a small geographic range than in a large one.
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The catalog of Earth’s biodiversity is very incomplete. About 1.9 million species have scientific names. Estimates of the total number of living species cluster around 10 million, which means that most species have not been discovered and described. (These estimates omit bacteria because of the practical problems in defining bacterial species.) Simply counting species must be, at best, an incomplete measure of biodiversity, for most species cannot be counted within a reasonable time. At the present rate of describing new species, it will take about 1,000 years to complete the catalog of scientific names. Of the approximately 1.9 million species now described, perhaps two-thirds are known from only one location and many from examining only one individual or a limited number of individuals, so knowledge of the genetic variation within species is even more constrained. From just a few well-studied species, it is clear that genetic variability can be substantial and that it differs in extent between species.
It should be noted that the pace of species population declines and extinctions has risen dramatically over the last century, as the effects of climate change increased and human activities such as agriculture, fishing, and hunting continued to encroach into more-remote natural areas. A 2019 report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services noted that up to one million plant and animal species are facing extinction due to human activity. (The loss of biodiversity as a result of human activity and various methods aimed at preventing this loss are discussed in the articles conservation and biodiversity loss.)
To assist in the daunting challenge of protecting species, a number of biologically rich but threatened regions containing high numbers of endemic species have been identified and mapped. Such “hot spots” of biodiversity have been described to assist governments and nongovernmental organizations in the development of conservation priorities.
The United Nations named 2010 as the International Year of Biodiversity (IYB)—a yearlong celebration intended to raise public awareness about the importance of biodiversity and to reinforce conservation efforts. Many of the conservation goals promoted by the IYB have resurfaced periodically in later United Nations awareness campaigns—such as the International Year of Forests (2011), the International Year of Soil (2015), and the International Year of Sustainable Tourism for Development (2017).
Biodiversity is the variety of life found in a place or on Earth, measured by species richness, genetic diversity, and ecosystem diversity. Learn how biodiversity is weighted differently for different species and habitats, and why it is important for conservation.
Learn how to measure species diversity using richness, evenness, and Shannon index. Explore different species concepts and their implications for biodiversity conservation.
definition. biodiversity. variety of life or living organisms present in a region. ecological biodiversity. diversity seen across different ecosystems. species biodiversity. diversity in species number and type within an ecosystem. genetic biodiversity. diversity in characteristics within a single species due to genetic differences.
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Definition. Species diversity refers to the variety and abundance of different species within a given ecological community or environment. It is a crucial aspect of biodiversity, encompassing both the number of species (richness) and their relative abundance (evenness), which contribute to the overall health and stability of ecosystems.
