Mitochondrial phylogeny of the endemic Hawaiian craneflies (Diptera, Limoniidae, Dicranomyia): Implications for biogeography and species formation

Abstract

Situated in the middle of the Pacific Ocean, over 3000 km from the nearest continental land mass, the Hawaiian Archipelago is the most remote island group on earth. The Hawaiian Islands are often referred to as a ‘‘conveyor belt” archipelago (Carson and Clague, 1995); as the Pacific plate moves to the northwest over a stationary hotspot, islands are formed, carried with the plate, and gradually subside at a more-or-less constant rate (Price and Clague, 2002; Ziegler, 2002). This hotspot has been active for over 40 million years (Carson and Clague, 1995) and has resulted in a chain of successively older islands, seamounts, and atolls stretching northwest across the Pacific. Currently, there are eight ‘‘high islands” in the southeast of the chain that, at over 1000 m in elevation, are able to support a diverse flora and fauna. The youngest island, dated at less than 600,000 years old, is the Big Island of Hawai‘i. Kaua‘i, at about 5 million years old, is the oldest high island (Price and Clague, 2002). Extreme isolation, coupled with the unique geology and environmental conditions of the islands, has made Hawai‘i a ‘‘natural laboratory” where the effects of evolution are readily observable (Kaneshiro, 1995). Over 850 endemic flowering plant (Wagner et al., 1990) and 4000 endemic insect species (Liebherr, 2001) are each thought to have been derived from about 200 colonization events. Colonist species can rapidly fill open ecological niches and diversify in situ, resulting in an amazing array of endemic fauna and flora. Newly emerging islands are then colonized from