Department of Natural Resources, Cornell University
Mechanisms maintaining sharp genetic clines
in marine species with long-lived larvae.
Wednesday — October 3, 2012
Pacific Forum — 3:00 p.m.
Patterns of clinal genetic variation in marine species provide for informative spatial contrasts that help identify demographic and evolutionary mechanisms maintaining the pattern. Contemporary mechanisms that could contribute include: (1) physical barriers to dispersal, (2) biotic barriers to gene flow, for example mediated by viability selection across habitat heterogeneities, and (3) gamete incompatibilities and other intrinsic factors lowering the fitness of immigrants interbreeding with locals. I will present results bearing on these mechanisms for the remarkably sharp genetic cline in eastern oysters, Crassostrea virginica, along eastern Florida. These population genetic and field experimental results collectively support a combination of abiotic and biotic barriers limiting the contemporary mixing and homogenization of oyster populations. These inferences help inform the geographic scale of local adaptation in oysters as well as improving our knowledge of population connectivity among lagoon populations.