Spiders of the Caribbean: Patterns and Processes of the Diversification in the Spider Genus Selenops (Araneae; Selenopidae)

In the Caribbean, the relatively few biogeographic studies conducted on arthropods are based on morphology alone (e.g.- carabids, Liebherr 1988), or else have focused on taxa that are not dispersal limited or (e.g.- butterflies, Davies and Bermingham 2002). The use of arthropods is important, as sample sizes can generally be much larger than those found in vertebrates. Also, if disparate taxa display similar patterns, this provides evidence for common processes underlying these patterns. I have chosen to focus on the spider genus Selenops. These relatively large spiders were last revised by Muma (1953) on the basis of genitalic characteristics which have recently been demonstrated to be highly variable making them potentially unreliable for species determination (Crews 2003). Many species have been described from only a single male or female specimen or are undescribed (Hounsome 1994). I have selected Selenops as a focus group because over 40% of the described species in this tropical I subtropical genus occur in the Caribbean region, with many species being single-island endemics. These spiders are habitat restricted, occurring only in heavily forested areas. To date, there have been no biogeographic studies of spiders in the Caribbean region, although other studies of the biogeography of spiders on islands are available as a basis for comparison (Gillespie 1999 - Hawaii; Amedo et al. 2001 - Canary Islands; Oxford and Gillespie 2001 - Hawaii; Hormiga et al. 2003 - Hawaii). The questions this research will address are listed below: I.) Did lineages comprising the genus Selenops arise through dispersal or vicariance? II) Do the patterns of divergence in Selenops indicate the presence of ecotypes? III.) Do Selenops found in the Caribbean, Central America & Mexico and the Galapagos Islands demonstrate the same biogeographic patterns as that found in Darwin's finches? IV.) Why are some species widespread while other Selenops are restricted?