The Hawaiian Islands are home to some of the world's most spectacular examples of adaptive radiation and offer an unparalleled environment in which to study the evolutionary consequences of ecological opportunity. The twenty described Hawaiian crab spiders (Araneae: Thomisidae) are exceptionally diverse in coloration, reflecting species-specific specializations of mimicry onto a variety of microhabitat types including leaves, moss and lichens. While the diversity of the Hawaiian species led earlier systematists to place the Hawaiian thomisids into several unrelated genera, recent analysis based on genital morphology led to the hypothesis that all 20 species in fact comprise a single large adaptive radiation. To date there has been no explicit phylogenetic test to determine whether the spiders comprise a single or multiple lineages. In this study, a phylogenetic investigation of Hawaii's endemic crab spider fauna is conducted based on mitochondrial and nuclear DNA sequence data. The resulting phylogenetic hypothesis is used to assess (1) levels of speciation following initial colonization, (2) whether changes in spider coloration appear to coincide with habitat coloration changes, and (3) the extent to which the geology of the archipelago can explain the phylogeny of its endemic crab spiders. These analyses indicate that while the Hawaiian thomisids may not be monophyletic, extensive autochthonous speciation via ecological shifts and within archipelago isolation accounts for their tremendous diversity.
Keywords: phylogenetic systematics, mimicry evolution
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA