November 4 2009
12:00 LSB 2320
Department of Integrative Biology, UC Berkeley
Diversification rate, ecological limits, and the variation in species richness among clades and regions
Summary:
One of the most striking patterns in the natural world is the disparity in species richness among groups of organisms: many groups are species poor, yet some are characterized by overwhelming diversity. Similar patterns describe the spatial distribution of biological diversity. Here, I consider the estimation of species diversification rates from molecular phylogenies and show how such analyses can help us to understand the interplay between diversification rates (speciation, extinction), ecology, and species richness. I address the causes of differential diversification at two levels. First, I consider the relative importance of evolutionary age, diversification rates, and ecological factors in generating patterns of species richness in higher taxa. Second, I look at the potential mechanisms underlying the apparent 'explosive' diversification patterns frequently seen in species-level radiations. I discuss evidence for alternative paradigms to explain species richness that challenge our notions of "evolutionary rate" and "radiation."