Meeting Abstract
The known species diversity of phoronid worms is low (two genera and 11 accepted species) when compared to brachiopods and many other marine invertebrate groups. As such, our goals were to better estimate phoronid species diversity, detect cryptic species, and discern phylogeographic patterns in select lineages using mitochondrial, ribosomal, and nuclear genes. Overall, molecular data support a closer relationship among Phoronopsis spp. and infaunal Phoronis spp. that brood embryos in the lophophore. Results from mitochondrial genes suggest that these markers have been subjected to purifying selection among phoronid species. However, specific lineages (e.g., Phoronis pallida) exhibit divergent cytochrome c oxidase subunit I (COI) haplotypes that include several (inferred) novel amino acid differences. It is plausible that these differences are the result of adaptive selection from a commensal relationship with thalassinid mud shrimps. Populations of P. pallida from sites in Puget Sound, WA and Hatfield, OR, USA contain two distinct and largely concordant genetic parsimony networks. Members of the smaller network exhibit an intermediate level of genetic divergence (~6-7%) from all other P. pallida haplotypes. When considering intraspecific genetic distances estimated from other phoronid species, the divergent clade of P. pallida may suggest sympatric incipient speciation or possibly a cryptic species. Although further sampling is needed, and AMOVA analyses do not support significant differences among sites, geographic differences in haplotype subclade frequencies are evident.
