Population genetics of hudson bay marine mammals: Current knowledge and future risks

Abstract

Hudson Bay has experienced, and is predicted to further undergo, significant environmental changes that may affect the distribution of marine mammals. These changes will affect gene flow among regions within the greater Hudson Bay ecosystem, as well as between Hudson Bay and the rest of the Arctic. Currently, there are few genetic studies that include marine mammals from Hudson Bay, even though this area is critical to understanding how Arctic species will adjust to climate changes. Within this region, some marine mammals may become extirpated or isolated (e.g., southern Hudson Bay polar bears), while other species may expand their ranges (e.g., killer whales, harbour seals) as a result of warmer temperatures. Researchers and the public should view the greater Hudson Bay ecosystem as an early warning system for the larger Arctic ecosystem. For population geneticists, marine mammals pose a unique challenge because they show little differentiation over large spatial scales due to: large historical population sizes; high mobility; seasonal migration; and breeding patterns that promote gene flow. Genetic monitoring programs need to take these factors into account in order to be effective. If designed carefully, these programs can be used to track changes in marine mammal populations that result from climate change. We survey current genetic data collected from marine mammals in Hudson Bay and suggest possible trajectories that may result from temporal shifts in ice thaw and decreasing overall ice cover. We also comment on sampling strategies that will allow for the effective monitoring of genetic changes. © 2010 Springer Netherlands.