Radiation of the bark louse genus Kilauella across the Hawaiian Islands

Abstract

Island systems serve as important models for studies of evolutionary processes and speciation. The Hawaiian Island group is one of the most isolated island chains in the world, and many groups of insects have undergone dramatic diversification within these islands. Studies of adaptive radiation on Hawaii could promote understanding of the evolutionary process underlying diversification patterns, but studies of Hawaiian taxa from a systematics standpoint are limited. The bark louse genus Kilauella (Psocoptera: Elipsocidae) represents one of the most abundant genera of insects across all islands of the Hawaiian chain, and is a prime candidate for a phylogenetic study. This work aims to explore the diversification pattern of these bark lice across the modern high islands. Kilauella specimens were collected from the islands of Kauai, Oahu, Molokai, Maui Nui, and Hawaii to create a phylogeny exploring the speciation patterns of the genus. Our results show evidence of forward ‘stepping stone’ radiation across the Hawaiian Islands with a potentially significant level of within island radiation, but resolution in the phylogeny is a problem for elucidation of an exact pattern. Molecular dating estimates show that genus Kilauella may be a relatively young radiation, with an origin at approximately 6.74 mya (95% confidence interval 9.48 to 4.38 mya), corresponding roughly with the uplift of the island of Nihoa at 7.2 mya