SICB Division of Invertebrate Zoology (DIZ)

DIZ Researchers Database Entry

Michael Hart

Population genetics of reproductive variation
We study the population genetics of reproductive variation, mainly in echinoderms. Recent work in the northwest Atlantic looked at microsatellite and mtDNA population structure in sea urchins, sea stars, and clams in the context of Pleistocene glaciations, range expansion, and hybridization. New work in the Pacific focuses on life history and population genetic variation in the context of phylogenetic relationships among closely related species or genera of asterinid sea stars (see the diagram). Some species have dioecious adults with broadcast spawning of gametes followed by feeding (red lineages) or nonfeeding (orange) planktonic larval development, but many others have convergently evolved selfing hermaphrodite adults with non-planktonic larval development in egg masses (green) or viviparous brooding with live birth and sibling brood cannibalism (blue). The new work has several directions: (1) comparison of microsatellite and DNA sequence estimates of inbreeding and population structure among species with different larval forms and mating sytems; (2) analysis of selfing and multiple paternity in species with benthic brooding; (3) study of fertilization kinetics and hybridization potential in species with planktonic gametes; (4) characterization of genes encoding gamete recognition proteins and their sequence variation within and among species with different mating systems. We are actively recruiting new graduate students or postdocs interested in this work, especially projects (3) and (4).