Population divergence and gene flow estimation
Applications of population genetics have become common at all spatial and temporal scales of analysis in evolutionary ecology, from inferences about mating systems to predictions about biogeographic responses to climate change. Characterizing rates and patterns of genetic exchange among populations (aka "gene flow") has become a particularly useful tool in understanding a variety of issues in ecology and evoluiton, such as local adaptation, speciation, and connectivity among threatened, harvested, and recovering natural populations. Although tagging studies provide some insight into the movements of individuals, inferences about gene flow and and associated parameters (such as dispersal distances and immigration rates) are typically made from studying patterns of genetic differentiation or divergence among populations.
Our lab has been involved with a variety of research projects focused on gene flow among natural populations of organisms, but with an emphasis on understanding gene flow as one of several interacting evolutionary forces that shape to patterns of genetic differentiation among populations and species over time. At present, the methods that offer the greatest potential insight into the causes of population divergence (including gene flow) are those based on the coalescent, which use information stored in the genealogical structure (shape) of gene trees (that extend back in time from the present) to jointly model the evolutionary forces responsible for observed patterns of divergence in the present.
Marko, P. B. and M. W. Hart. 2011. The complex analytical landscape of gene flow inference. Trends in Ecology and Evolution 26: 448-456. [PDF]
Marko, P. B. and M. W. Hart. 2011. Retrospective coalescent methods and the reconstruction of metapopulation histories in the sea. Evolutionary Ecology. [PDF]
Nance, H.A., Klimley, P., Galvan-Magna, F., Martinez-Ortiz, J., & P. B. Marko. 2011. Demographic Processes Underlying Subtle Patterns of Population Structure in the Scalloped Hammerhead Shark, Sphyrna lewini. PLoS One 6: e21459. [PDF]
Hart, M. W. & P. B Marko. 2010. It’s about time: divergence, demography, and the evolution of developmental modes in marine invertebrates. Integrative and Comparative Biology 50:643-661. [PDF]
Marko, P. B. & A. L. Moran. 2009. Out of sight, out of mind: High cryptic diversity obscures the identities and histories of geminate species in the marine bivalve subgenus Acar. Journal of Biogeography 36: 1861-1880. [PDF]
Marko, P. B. & K. B. Barr. 2007. Basin-scale patterns of mtDNA differentiation and gene flow in the Bay Scallop, Argopecten irradians concentricus Say. Marine Ecology Progress Series 349: 139-150. [PDF]