Drs. Toonen and Grosberg will study population genetic variation and reproduction in sea stars (Asterinidae, or bat stars) found in shallow temperate and tropical oceans around the world. Marine population genetic variation has largely been interpreted in terms of dispersal differences: strong genetic drift among populations, local inbreeding, frequent local extinction, and potential for local adaptation in species without planktonic larvae; strong gene flow, little genetic drift, limited inbreeding, and fewer opportunities for speciation or extinction in species with widespread larval dispersal. However, recent studies in various organisms and oceans using diverse genetic markers suggest that this view is limited. Processes other than dispersal in ocean currents may have a predominant influence on population genetic structure. Many species may not be expected to approach population genetic equilibrium between dispersal, gene flow, mutation, and genetic drift.
This research will help to test these expectations and expand the view of population genetic variation in the ocean by (1) comparing population structure using multiple genes for different bat star lineages and species with modified life cycles; (2) assessing the contribution of other life cycle differences (especially selfing and internal fertilization) to population genetic patterns; (3) using known phylogenetic relationships among species to ask how often convergent evolution of life cycle traits has resulted in similar population genetic patterns; (4) evaluating the contribution of historical processes such as geographical range expansion, climate change, or recent speciation events that could push population genetic patterns away from expected patterns based on dispersal potential; (5) estimating the impact of gene flow and population structure on the evolution of reproductive incompatibility between gametes (at fertilization) or between genomes (during larval development).
The investigators and their students will join an established collaboration involving Canadian and Australian researchers. Female, native Hawaiian, and Australian Aboriginal student researchers from all four institutions will work in diverse field (Alaska, British Columbia, California, Baja, Queensland, New South Wales) and lab settings. These students will develop a combination of skills in molecular genetics, quantitative analysis, phylogenetics, and reproductive biology. If previous studies are any guide, the results are likely to contribute to basic knowledge of biological diversity in the ocean by identifying new cryptic species. The comparative population genetic analysis will help marine ecologists and conservation biologists understand the mix of factors that contribute to population structure and local genetic diversity. Such knowledge is crucial to issues such as the location and management of marine protected areas in California, the conservation status of some endangered Australian asterinids that are threatened by coastal development and noxious invasive species and have been given protected status; and the unique genetic properties of the marine organisms in the proposed Gwaii Haanas World Heritage Site in the Queen Charlotte Islands.
