Meeting Abstract
48.1 Tuesday, Jan. 5 Dynamics of speciation, larval dispersal, and biogeographic overlap in a pantropical group of crustacea, the fiddler crabs LEVINTON, Jeffrey *; MACKIE, Joshua; KOZAK, Kenneth; RODGERS, Brooke; Stony Brook Univ.; Moss Landing Marine Lab.; Bell Museum of Natural History; Stony Brook Univ. levinton@life.bio.sunysb.edu
Geographic overlap of closely related species is of crucial interest because its character and degree have important ecological and evolutionary consequences. Using morphological, molecular and GIS-based geographic range data we investigated the phylogeny and biogeography of fiddler crabs (genus Uca). We used a GIS system ARCMAP to quantify the geographic distributions of fiddler crabs in the western Pacific and Indian Ocean, eastern Pacific, and western Atlantic into 50×50 km units and compared these ranges with the phylogenetic relationships of fiddler crabs as determined from subgenus membership, and a tree based on morphological characters. We consider three main biogeographic regions: western Atlantic, eastern Pacific, and Indo-Pacific. Geographic range overlap of coexisting species differed substantially among regions, with the most overlap in the eastern Pacific and the Gulf of Mexico. Overlap in the Indo-Pacific cannot be readily distinguished from a random distribution. Among regions there are consistent and differing monotonic patterns between geographic range and overlap with other species. We found no differences among subgenera, suggesting that phylogenetic position has no influence on biogeographic overlap patterns. Even though there are strong geographic associations the most closely related sister species arising recently, we found no relationship of geographic clade overlap and evolutionary history (node depth); this suggests that, with passing time, dispersal erases the evolutionary footprints. The strong overlap in the eastern Pacific and Gulf of Mexico probably results from basin confinement, which allows planktonic larval dispersal to result in extensive overlap. Basin confinement may be unimportant in the Indo-Pacific.
