MICROSATELLITE DNA REVEALS SURPRISING LEVELS OF GENETIC STRUCTURE WITHIN AND AMONG REMNANT POPULATIONS OF THE OLYMPIA OYSTER, Ostrea conchaphila.
The Olympia oyster, Ostrea conchaphila, the only oyster species native to the Pacific Northwest, once ranged from Southeastern Alaska southward through Baja California in densities capable of supporting subsistence and commercial fisheries. Over-exploitation, habitat degradation, and introductions of non-native species have drastically depleted historic densities and extirpated many local populations. Currently, there is intense interest in restoring this species to recover the ecological benefits provided by oyster reefs, and some restoration programs use hatchery-produced seed oysters. Unfortunately, but unavoidably, these efforts are proceeding without a clear understanding of existing genetic structure among populations, thus risking negative impacts at the genetic level if oysters are transplanted among populations while at the same time potentially risking perpetuating existing genetic-level problems such as inbreeding caused by recent population bottlenecks if oysters are not translocated.
Using microsatellite DNA markers recently developed in our laboratory, we studied genetic differentiation among and within major geographical regions of the northern portion of the Olympia oysters original range. We found much more genetic structure than anticipated both among regions and within Puget Sound, supporting the hypothesis that translocating oysters has the potential to alter the existing genetic composition of populations. It is important, however, to appreciate that these analyses of variation in allele frequencies at presumably neutral microsatellite DNA markers are only a first step and does not address whether or not populations are locally adapted and thus whether translocation and its genetic impacts would be helpful or harmful. We, therefore, briefly discuss research strategies to address this key question.
Using microsatellite DNA markers recently developed in our laboratory, we studied genetic differentiation among and within major geographical regions of the northern portion of the Olympia oysters original range. We found much more genetic structure than anticipated both among regions and within Puget Sound, supporting the hypothesis that translocating oysters has the potential to alter the existing genetic composition of populations. It is important, however, to appreciate that these analyses of variation in allele frequencies at presumably neutral microsatellite DNA markers are only a first step and does not address whether or not populations are locally adapted and thus whether translocation and its genetic impacts would be helpful or harmful. We, therefore, briefly discuss research strategies to address this key question.