Multiple, independent colonizations of the Hawaiian Archipelago by the family Dolichopodidae (Diptera)

Abstract

The family Dolichopodidae forms two of the four largest evolutionary radiations in the Hawaiian Islands across all flies:Campsicnemus(183 spp) and theEurynogastercomplex (66 spp). They also include a small radiation ofConchopus(6 spp). A handful of other dolichopodid species are native to the islands in singleton lineages or small radiations. This study provides a phylogenetic perspective on the colonization history of the dolichopodid fauna in the islands. We generated a multi-gene data set including representatives from 11 of the 14 endemic Hawaiian dolichopodid genera to examine the history of colonization to the islands, and analyzed it using Bayesian and maximum likelihood phylogenetic methods. We used a subset of the data that includedConchopusand the eight genera comprising theEurynogastercomplex to estimate the first phylogenetic hypothesis for these endemic groups, then used Beast to estimate their age of arrival to the archipelago. TheEurynogastercomplex, CampsicnemusandConchopusare clearly the result of independent colonizations.The results strongly support theEurynogastercomplex as a monophyletic group, and also supports the monophyly of 4 of the 8 described genera within the complex (Adachia, Arciellia, UropachysandEurynogaster). Members of the family Dolichopodidae have been dispersing over vast distances to colonize the Hawaiian Archipelago for millions of years, leading to multiple independent evolutionary diversification events. TheEurynogastercomplex arrived in the Hawaiian Archipelago 11.8 Ma, well before the arrival ofCampsicnemus(4.5 Ma), and the even more recentConchopus(1.8 Ma). Data presented here demonstrate that the Hawaiian Dolichopodidae both disperse and diversify easily, a rare combination that lays the groundwork for field studies on the reproductive isolating mechanisms and ecological partitioning of this group.