The ecological and genomic basis of explosive adaptive radiation

Rates of speciation vary tremendously among evolutionary lineages, with our understanding of what fuels the rapid succession of speciation events within young adaptive radiations remaining particularly incomplete. The cichlid fish family provides the most notable example of such variation among extant metazoans. It includes many slowly speciating lineages as well as the several exceptionally large and rapid adaptive radiations. By reconstructing a large phylogeny of all described cichlid species, we show that explosive speciation is solely concentrated in several large yet young lake species flocks. Across the family, speciation rate increases are associated with absence of top predators, and speciation rate decreases are associated with arid climate, but these factors are not nearly sufficient to explain explosive speciation in lake radiations, in particular the Lake Victoria adaptive radiation. Across lake radiations we observe a positive relationship between speciation rate and enric...