Meeting Abstract

P1.174  Saturday, Jan. 4 15:30  Cryptic speciation in Phascolosoma agassizii (Sipuncula) detected with mitochondrial sequence data JOHNSON, N.D.*; SCHULZE, A; Texas A&M University at Galveston njohnso1@neo.tamu.edu

The advent of molecular sequencing has opened new avenues for taxonomy of marine species. These new methods allow us to construct a more thorough history of speciation events and population distributions than those based on solely morphological observations. Not surprisingly, molecular identification techniques have helped to identify many new cryptic species, or distinct genetic lineages which share morphological features yet differ significantly in their genetic makeup. The recognition and description of cryptic species is critical for accurate estimates of biodiversity, proper taxonomic classifications, and the conservation of many marine species and habitats. The sipunculan Phascolosoma agassizii is one such example of strong genetic divergence among populations overlooked because of similar morphologies. Previously believed to have a cosmopolitan distribution within the North Pacific, recent data suggest the presence of two geographically separated cryptic species. Phylogenetic reconstructions based on mitochondrial sequence data show two strongly divergent clades, one from the North American west coast and one from the Sea of Japan. Our research seeks to characterize the inter- and intrapopulation divergence, by expanding the geographic sampling regime in both regions. We were able to collect samples from Monterey Bay, Friday Harbor, British Columbia, the Kuril Islands, Peter the Great Bay, and Sokcho Bay. Our phylogenetic analyses show that the two lineages are not even sister taxa and diverged relatively early in the radiation of the genus. Thus, the separation is not only based on an arbitrary threshold of genetic distance, but is also supported by the evolutionary history of the genus. More detailed morphological analyses may reveal subtle differences in the future.