Phylogeography of the widespread Caribbean spiny orb weaver .

BACKGROUND

Modern molecular analyses are often inconsistent with pre-cladistic taxonomic hypotheses, frequently indicating higher richness than morphological taxonomy estimates. Among Caribbean spiders, widespread species are relatively few compared to the prevalence of single island endemics. The taxonomic hypothesis circumscribes a species with profuse variation in size, color and body form. Distributed throughout the Neotropics, is the only morphological species of in the New World in this globally distributed genus.

METHODS

We inferred phylogenetic relationships across Neotropical populations of using three target genes. Within the Caribbean, we estimated genetic diversity, population structure, and gene flow among island populations.

RESULTS

Our findings revealed a single widespread species of throughout the Caribbean, , while suggesting two recently divergent mainland populations that may represent separate species, diverging linages, or geographically isolated demes. The concatenated and (Cytochrome c oxidase subunit 1) phylogeny supported a Caribbean clade nested within the New World. Genetic variability was high between island populations for our dataset; however, gene flow was also high, especially between large, adjacent islands. We found structured genetic and morphological variation within island populations; however, this variation does not reflect genealogical relationships. Rather, isolation by distance and local morphological adaptation may explain the observed variation.