September 1, 2014.
Eelgrass (Zostera marina) is a highly clonal marine angiosperm that can also reproduce sexually through flowering and seed formation. In a previous study, Fst values from six microsatellite loci suggested that a perennial San Francisco Bay subpopulation at Point Molate (Richmond, California) was able to recover from a drastic 2006 die-off through seed recruitment from neighboring eelgrass subpopulations, changing its reproductive strategy from clonal to sexual. Although Fst measures continue to be widely used in population genetics, the assumptions under which they operate are not always appropriate given certain circumstances, such small population sizes and/or asymmetrical migration rates. Our summer research goal was to re-analyze the microsatellite data with the program MIGRATE, which uses coalescent-based analyses to estimate posterior probability distributions for genetic parameters such as effective population size and migration rates. With MIGRATE, we employed a Bayesian approach to infer migration rates between three Point Molate subpopulations (2005, 2007, and 2008) and its neighboring subpopulations at Point San Pablo, Point Orient, and Keller Beach. To add to an ongoing study of its temporal genetic variation, we collected 46 vegetative shoots from Point Molate for future genotyping. We also collected 50 vegetative shoots from Tomales Bay (Marshall, California) for a future study on genetic connectivity of inner and outer SF Bay eelgrass subpopulations. Results from MIGRATE analyses are still in preliminary stages and require further manipulation before a conclusive interpretation can be reached.
Biodiversity | Computational Biology | Ecology and Evolutionary Biology | Genetics | Marine Biology | Population Biology
C. Sarah Cohen
Romberg Tiburon Center for Environmental Studies (RTC)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).