Island life accelerates geographic radiation in the white‐eyes (Zosteropidae)

Abstract

White‐eyes are an iconic avian radiation of small passerines that are mainly distributed across the eastern hemisphere tropics and subtropics. Species diversity of white‐eyes is particularly high on oceanic islands, and many species are restricted to single islands or island groups. The high rate of species diversification of white‐eyes ranks them among the fastest radiations known in birds, but whether their accelerated diversification was the result of repeatedly colonizing islands remains unexplored. We used a newly estimated timetree for nearly all zosteropids and phylogenetic comparative methods to estimate and compare diversification rates between island and continental lineages. We show that island white‐eyes have similar extinction rates, yet higher speciation rates compared with continental white‐eyes. In addition, we find higher rates of transitions from islands to continents. Our results show the importance of islands, such as Wallacean and Melanesian archipelagos of the Indo‐Pacific, in facilitating high rates of speciation within this remarkable clade.