4aMeasuringBiodiversityprela - Exercise 4A [Pre-Lab]...

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Biology 6C 83 Exercise 4A [Pre-Lab] Measuring Biodiversity Parts of this lab adapted from General Ecology Labs , Dr. Chris Brown, Tennessee Technological University and Ecology on Campus , Dr. Robert Kingsolver, Bellarmine University. In this lab exercise, we will examine several concepts related to biodiversity . The term biodiversity describes the number and abundance of species inhabiting a community, habitat or other described area. The most basic measure of biodiversity is species richness (S), a total count of species present in the defined area. However, species richness does not give a complete picture of biodiversity. In this exercise, we will examine not only species richness, but also methods to determine relative abundance (the proportion of each species present), species evenness (how equal in abundance species are) and calculate the Shannon Index , a measure of biodiversity. Introduction So, how many species are there on the planet? This question is easier to ask than to answer, because we have discovered and described only a fraction of the earth's biota. Most large terrestrial organisms, such as birds and mammals, are so well inventoried that discovery of a new species in these taxonomic groups is a newsworthy event. At the other extreme are soil bacteria, often impossible to culture in standard media, and so poorly studied that there are probably a number of undescribed species thriving beneath your campus grounds. In his influential book The Diversity of Life, ecologist E. O. Wilson (1999) reports an estimate of 1.4 million described species, based on interviews with taxonomists specializing in a wide variety of organisms, and comprehensive reviews of databases and museum records. As for the numbers of living species not yet known to science, estimates range from 5 million to 100 million. As ecologists discover new taxonomic categories and new microhabitats, they are constantly revising their estimates. Wilson's argument for more attention to taxonomic questions in biology is compelling, since intelligent management decisions for global species protection begin with some idea of the number of species we have to protect. How can we improve our appraisal of biodiversity yet to be discovered? One practical approach is based on repeated sampling of a type of organism in a particular place, using the growing database to develop a species accumulation curve. To show how this works, let's visit La Selva, Costa Rica's national rainforest preserve. Here entomologists John T. Longino and Robert Colwell have been collecting ants from the leaf litter of the forest floor in an extended survey of the insect fauna of the park. One of their methods for trapping specimens is the Berlese apparatus. Leaf litter collected from the forest floor is returned to a lab and placed in a
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This note was uploaded on 09/02/2011 for the course BIOL 6C taught by Professor Sundram during the Spring '09 term at DeAnza College.

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4aMeasuringBiodiversityprela - Exercise 4A [Pre-Lab]...

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