Affiliation:
1. Center for Conservation Research and Training, Pacific Biosciences Research Center, University of Hawaii3050 Maile Way, Gilmore 408, Honolulu, HI 96822, USA
Abstract
Oceanic islands have played a central role in biogeography and evolutionary biology. Here, we review molecular studies of the endemic terrestrial fauna of the Hawaiian archipelago. For some groups, monophyly and presumed single origin of the Hawaiian radiations have been confirmed (achatinelline tree snails, drepanidine honeycreepers, drosophilid flies,
Havaika
spiders,
Hylaeus
bees,
Laupala
crickets). Other radiations are derived from multiple colonizations (
Tetragnatha
and
Theridion
spiders, succineid snails, possibly
Dicranomyia
crane flies,
Porzana
rails). The geographic origins of many invertebrate groups remain obscure, largely because of inadequate sampling of possible source regions. Those of vertebrates are better known, probably because few lineages have radiated, diversity is far lower and morphological taxonomy permits identification of probable source regions. Most birds, and the bat, have New World origins. Within the archipelago, most radiations follow, to some degree, a progression rule pattern, speciating as they colonize newer from older islands sequentially, although speciation often also occurs within islands. Most invertebrates are single-island endemics. However, among multi-island species studied, complex patterns of diversification are exhibited, reflecting heightened dispersal potential (succineids,
Dicranomyia
). Instances of Hawaiian taxa colonizing other regions are being discovered (
Scaptomyza
flies, succineids). Taxonomy has also been elucidated by molecular studies (
Achatinella
snails, drosophilids). While molecular studies on Hawaiian fauna have burgeoned since the mid-1990s, much remains unknown. Yet the Hawaiian fauna is in peril: more than 70 per cent of the birds and possibly 90 per cent of the snails are extinct. Conservation is imperative if this unique fauna is to continue shedding light on profound evolutionary and biogeographic questions.
Subject
General Agricultural and Biological Sciences,General Biochemistry, Genetics and Molecular Biology