Immigration history controls diversification in experimental adaptive radiation

Bursting to evolve The diversity of life is thought to have arisen through a series of 'bursts' of evolution, or 'adaptive radiations'. What conditions cause these bursts, and why do they occur after mass extinctions, on islands, and sporadically through time? Justin Meyer and Rees Kassen provide experimental evidence, in a community containing the protozoan Tetrahymena thermophila and its bacterial prey, that the evolutionary processes causing the bursts are influenced by predators. For reducing prey populations, predators slow the rate at which prey species diverge into new forms. Predators are rare on deserted islands, and at times of mass extinctions, suggesting that their absence is a catalyst to the bursts of evolution that occur then. In a separate paper Fukami et al. use model bacterial populations to show that biodiversity is a product of both the ecological process of immigration into communities, and the evolutionary process of diversification within communities.