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Biodiversity

This is a multimedia record for the chart that will be displayed on the "Biodiversity" page.
This is a multimedia record for the chart that will be displayed on the "Biodiversity" page.

What is biodiversity and how do we measure it? Biodiversity refers to the variety of organisms on earth and is commonly expressed as the number of species in a given area or environment. The number of species that a biologist or paleontologist finds is related to the number of specimens they examine. A large sample of specimens will yield more species than a smaller sample of specimens. Rarefaction curves help us calculate the number of different species represented in a community based on the number of samples collected. 

This graph is a rarefaction curve that shows the number of species recorded from Silurian reef collections in the Milwaukee Public Museum. The study of 3000 specimens produced a record of 140 species. At 6000 specimens, 165 species were recorded. A total of 191 reef species were recorded at the final sample size of 10,201 specimens. Note that the curve does not reach a plateau and an examination of additional specimens would add to the number of recorded species.