11-10-09 - Biology 330 Class Notes 11/10/09 See written...

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Biology 330 – Class Notes – 11/10/09 See written notes for lab notes and calculations Species Area Curves The cumulative number of species increases as new species are found. If a quadrat includes 6 of the same and 2 new species, then the cumulative number of species increases by 2 (only by the number of NEW species). As time goes on, it’s harder and harder to find new species , which results in a plateau or asymptote where there are no new species found The cumulative number of species increases ONLY when NEW species are found. If you go from 6 species to 8 species and only 2 of the 8 are NEW, you increase by only 2 on the cumulative number of species axis (y-axis). Number of species versus individuals/species GRAPH: If we compare our species list with the number of individuals for each species Common species are rare – species with very many individuals are rare (only a few of them) Rare species are common – there are many rare species that comprise the community. There are many species with low number of individuals KEY : the number of species and the number of individuals per species are NOT in equal portions I.E the number of individuals per species is NOT EQUAL – there will be more or less individuals per species. When there are few unique species, there will be many individuals of those species When there are many unique species, there will be few individuals for each species.
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BROKEN STICK MODEL If you break the stick in any random spot – that represents the resources commandeered by any one species . The remaining piece is what’s left to the rest of the community. Then break it again, the new piece goes to another species, and the rest of the stick is then left to the rest of the community. Repeat. This is how resources are allocated to species. One species was assumed to get: K The second species assumed to get K*(1-K) The third species assumed to K*(1 – (1-K)) Some of these models fit the data sets REALLY WELL Some of these models DON’T FIT THE DATA AT ALL One model doesn’t fit all the data sets ALL THE TIME THUS, Diversity is comprised of two components: 1. Species richness – the number of species in any one community. These are the number of categories (number of species ) 2. Equitability – Evenness of allocation of individuals among species present. How
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11-10-09 - Biology 330 Class Notes 11/10/09 See written...

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