Biol 201 - Notes - 4.13.2009

Biol 201 - Notes - 4.13.2009 - -McArthur’s Warblers o...

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Lecture Notes – 4.13.2009 – Biology 201 Patterns in species abundance: - Species abundance curve : number of species on y axis, number of individuals on x axis  o Shows normal curve; few are very abundant, few are very rare - Rank abundance curves o Count total, turn all amounts into proportions of total o Log scale of proportional abundance o The shape tells us about both species  richness  and  evenness  (structure of  community) o “species  diversity ” is some combination of those two measures o Greater evenness is indicated by lower slope o We can derive information about  dominance  (relative abundance of most abundant  species) Environmental complexity and community structure - Complex environments include many distinct microhabitats - Assuming there are trade-offs in performance between microhabitats, then this  heterogeneity can facilitate coexistence (more niches yay)
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Unformatted text preview: -McArthur’s Warblers: o Thought that they all had same niche, wondered how they could coexist. o The forests with the greatest volume of foliage above six meters contained five or more warbler species o Look at examples in slides Disturbance and species richness-A disturbance is any relatively discrete event that disrupts ecosystem, community, or population structure and changes resources, substrate availability or the physical environment. o Measured in terms of frequency and intensity -Intermediate disturbance hypothesis o Good colonizers vs. good competitors o Diversity is highest when disturbance is at intermediate frequency o Hypothesis only true if there’s a trade-off between being a good colonist and good competitor...
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Biol 201 - Notes - 4.13.2009 - -McArthur’s Warblers o...

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