The Systematics and Taxonomy of Fiddler Crabs: A Phylogeny of the Genus Uca

Abstract

Although fiddler crabs (genus Uca) have been among the most widely studied organisms with respect to sexual selection, agonistic behavior, asymmetry, and visual and acoustic signaling, the phylogenetic relationships within the genus have remained largely a mystery. After reviewing the systematic history of the genus and its species, including a discussion of the systematic conflicts between two alternative proposals of subgeneric division, a phylogenetic analysis was performed for 88 species on a data matrix of 236 discrete morphological characters. These results were compared to a previously published molecular analysis of 16S ribosomal DNA for 28 species. To a large extent, the uncertainty in the proper taxonomic names for the subgenera can be resolved with these results, The biogeographic history of the genus is discussed, although these results do not provide enough support to allow complete resolution of the deep divergences between Indo-West Pacific and American clades. There is strong morphological evidence to support the monophyly of the broad-front taxa molecular evidence suggests biogeographic subdivisions.