REN R110 Lecture 33: Biodiversity Lecture 3
5 Mar 2017
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Life cycle variation: another challenge in determining s. Take home messages lecture 2: biodiversity is dynamic. We discussed two: simpson"s index (d) = 1/ /pi2 (pie = a-d, shannon-weiner index (h") = - pi x ln(pi, evenness, calculated as (j) = h"/lns, provides a measure of the uniformity of abundance among species. Steps toward a solution that you should now understand: Knowing s, j or sd does not tell us everything. Bray-curtis similarity: a measure of distance ranging from (most similar) to 1 (maximally dissimilar) Sum the absolute distance between the counts for each pair of species and divide by the sum of overall abundance in each sample. This index ignores species absent in both communities, although they may be present regionally, and is dominated by abundant species. Aggregate successive pairs of clusters with the smallest minimum pairwise similarity and re-calculate similarities for the new groups.
