Biogeography of Pacific insects and other terrestrial invertebrates: A status report

Because of their great diversity, insects and other invertebrates present excellent opportunities for biogeographic studies. Some of the features of insects include generality of distribution, much specialization within the context of overall versatility, many taxa possess rapid responses to environmental perturbation, some taxa are readily identifiable by non-specialists, many taxa are good indicators of areas of endemism, and many taxa are readily sampled with quantitative methods. Despite this, Pacific insect biogeography has advanced little since the now-classic studies by Gressitt and collaborators. Amongst the smaller Pacific islands, there is a basic pattern of depauperate, disharmonie biotas attenuating from west to east. In some cases, modern understandings of speciation processes, as well as tectonic, eustatic and human-induced background changes will require reinterpretation of traditional concepts. Most of the New Guinea insect biota shows closest relationships with that of Asia, with genera perhaps tending to be fewer in number but more species-rich. Most analyses have addressed the overall relationships of the New Guinea fauna, not regional endemism. Large scale experiments by Bishop Museum from 1957-1970 demonstrated the importance of dispersal, which may also be responsible for some distributions commonly considered to be introductions. But recent studies of both geology and biogeography indicate the importance of plate tectonics and rifted terranes as well.