PARENT SESSION
Contributed Oral Session 99: Populations and Genetics: Diversity and Population Dynamics
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 519 A, Level 5, Palais des congrès de Montréal
Genetic patchiness in Emerita analoga along the Pacific coast of North America.
Barber, Paul1, Gonzalez-Guzman, Laura*,2, Gaines, Steven 3, Dugan, Jennifer4, 1 Boston University, Woods Hole, MA, USA2 University of Texas at Austin, Austin, TX, USA3 University of California at Santa Barbara, Santa Barbara, CA, USA4 University of California at Santa Barbara, Santa Barbara, CA, USA
ABSTRACT- Many biogeographic provinces exist within the marine environment of the Pacific coast of North America. In addition to differences in community composition, intraspecific genetic variation is reported among populations of numerous marine species, particularly those spanning Point Conception, California. We examined patterns of genetic diversity in the sand crab Emerita analoga, in populations from southern Baja California to Washington. Mitochondrial cytochrome oxidase 1 sequence data revealed two clades, each characterized by a star phylogeny, a result consistent with a recent range expansion or high fluctuations in population size characteristic of this species. Analysis in AMOVA revealed no genetic structure and high gene flow among almost all pair-wise population comparisons. No discernable regional genetic structure was detected, even across biogeographic boundaries like Point Conception a pattern consistent with open population dynamics. However, the frequency of the two primary clades differed greatly among populations, counter to predictions of panmixia and open population structure. Instead of latitudinal clinal variation seen in some marine species in this region, there was no discernable pattern to the distribution of genetic variation. This spatial genetic heterogeneity may represent evidence of chaotic patchiness driven by variation in differential recruitment dynamics among populations. Absence of uniformity of genetic variation or clinal genetic structure suggests that dispersal and gene flow are not constant, but instead vary considerably over time. Thus, high gene flow estimates are likely driven periodic pulses of extremely high recruitment giving the appearance that populations of E. analoga are more open than they actually are.
Key words: Point Conception, Genetic connectivity, Emerita analoga, biogeography