P3.194 Friday, Jan. 6 Evolutionary history of the seagrass limpets Lottia depicta and Lottia paleacea SIMISON, Brian W; ARBISSER, Ilana M*; California Academy of Sciences email@example.com
Malacologists have long struggled to understand the phylogenetic relationships of the marine snails, Patellogastropoda, the “true limpets.” Difficulties arise in part because there are few morphological characters available for analysis. Many of these characters are convergent, making distantly related species appear the same. Additionally, the few characters available are phenotypically variable so that members of the same species often differ from one other. Recent advances in molecular systematics have vastly improved our understanding of phylogenetic relationships. Our objective was to better understand the phylogenetic origins of northeast Pacific seagrass limpets, L. depicta and L. paleacea. These limpets are particularly interesting because the seagrasses that host these limpets range from Baja to Alaska, but the two limpet species do not extend that far north. To better understand the evolutionary relationships of L. paleacea and L. depicta relative to the other New World limpets, we used 16S, a mitochondrial gene often used in molecular studies of other limpets. We collected limpets from Half Moon Bay, California and sequenced 16S for the collected specimens. We combined our sequences with those available from Genbank and some sequences provided by David Lindberg at the University of California at Berkeley. We aligned the sequences and inferred trees using MrBayes for Bayesian analyses, RaxML for maximum likelihood analyses and PAUP for parsimony bootstrap analyses. We found evidence supporting the hypothesis that L. depicta and L. paleacea are more closely related to tropical New World limpets than they are to other limpets that share their range. These findings have implications for our interpretations of the origins and biogeography of New World limpets. In addition, the narrow range of habitat preferences shown by seagrass limpets makes them useful as indicator species for climate change.