Climate change and the evolution of biodiversity
The climate of the Earth is subject to recurrent and rapid shifts at various time-scales, but their evolutionary role has rarely been considered. This projects aims to uncover the evolutionary consequences of climatic oscillations, especially their role in the extinction and origination of species.
In this project I will test five hypotheses: (1) The larger the climatic shifts, the lower the rate of species diversification (speciation minus extinction). (2) Much of the latitudinal gradient in taxonomic diversity is caused by lower diversification towards higher latitudes, where climatic shifts are larger. (3) The amplitude of climatic shifts is a better explanation for global variation in diversification rates than contemporary energy availability. (4) Large climatic shifts selects for good dispersal ability, since poorly dispersing species are more likely to go extinct during climatic shifts. (5) Large climatic shifts results in lower genetic divergence among populations.
The first three hypotheses are tested by sister-group analysis: two lineages of species with a common ancestor are compared. The lineage that has experienced less climatic variability is expected to have accumulated more species. The last two hypotheses are tested by relating plant seed mass and estimates of genetic divergence within species to the degree of past climatic variability experienced by species.