To investigate why some lineages undergo evolutionary radiation, we compare the
passerine avifaunas of the Hawaiian and Galápagos archipelagoes, which have supported
well-known radiations of birds, with those of the Lesser Antilles, which have not. We focus on
four steps required for the buildup of diversity through allopatric speciation and secondary
sympatry: genetic divergence in isolation, persistence of island populations, recolonization
of source islands, and ecological compatibility in secondary sympatry. Analysis of genetic …