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What is Biodiversity?

The term biodiversity encompasses the variety of life at scales that traditionally include individual organisms, populations, and ecosystems. Biodiversity researchers work to understand the nature of biological variation and the processes that affect it. As global processes like climate change affect the entire biosphere, biodiversity research even takes place on the scale of the entire planet.
Because biodiversity cuts across many levels of organization researchers typically focus on a particular type of diversity. For example:

  • Species diversity is a measure of the number and relative abundance of different species that exist in a given area. When people speak of biodiversity, most often they mean species diversity.
  • Genetic diversity is the amount and nature of genetic variability within populations. The survival of species often depends on genetic diversity at the population level, so understanding this variation is particularly important to conservation efforts.
  • Ecosystem diversity captures the variety of communities or habitats that exist and is much harder to measure than the previous two types. The difficulty arises because the boundaries of many communities or habitats may not be fixed like that of a pond, but rather gradually change from one type to another over a transition zone.


Despite their common name, green frogs (Lithobates clamitans) come in a wide range of colors, usually ranging from bright green to bronze and brown. A small fraction (about 1%) are a striking blue.

Photos by Bob Howe (left) and Dan Meinhardt.

How many Species are there on earth?

Approximately 1.4 million species have been formally described by scientists, but we know this number represents a minority of current species. Most estimates of the total number of living species tend to be in a range between 5 and 10 million (Wilson, 1999; Mora et al., 2011). Each year between 15,000 and 20,000 undescribed species are discovered and named. Most of these are non-vertebrate animals, plants, and bacteria, but new species of vertebrates are continually being discovered. In 1990, an undescribed monkey species was found, and the known number of frog species has increased by about 150 annually since 2004. Estimates made from Amazon fish markets suggest that 40 percent of South American freshwater fish species have yet to be formally described.

Importance of Biodiversity

The value of biodiversity is wide ranging. Practical values involve the role of organisms as food, sources of materials for creating shelter, life-saving medicines, and other useful substances like rubber. Many chemicals that are now synthetically produced were discovered first as parts of living organisms. The practical value of the services provided by entire ecosystems is enormous. Wetlands serve as important buffers to damaging flooding, clean the water we drink, and serve as important nurseries for species used for food and other purposes.
Biodiversity has great social, ethical, and cultural significance as well. Much of the world’s art, literature, and architecture is inspired by the living world. Experiencing natural landscapes is known to alleviate some forms of stress and anxiety, which themselves contribute to numerous health problems. Finally, many believe that biodiversity has intrinsic value, and that all walks of life deserve to be alive.