The study of phylogeography examines biogeographic patterns from an evolutionary (i.e., historical) perspective. In the lab, we are interested in the phylogeographic patterns of invertebrates living in the North Atlantic. To date, most genetic studies of North Atlantic organisms have focused on intertidal species. These species in particular are subject to range shifts and reduced habitat availability during periods of glaciation. In contrast, we have been interested in subtidal invertebrates that may have been more affected by other climatic influences.

Our initial work on this topic focused on the commercially important bivalve Arctica islandica, the Ocean Quahog. This clam is an important component of clam chowder, supports a multi-million dollar industry, and is commercially harvested in the USA, Canada, and Iceland. Unfortunately, this clam is very slow growing and is often greater than 60 years of age when harvested. It is also believed this organism takes approximately 10 years to reach reproductive age.


In a recent study, we, together with a collaborator from the National Marine Fisheries Service (Jim Weinberg), found that genetic diversity of this species was limited south of Cape Cod. We have hypothesized that a warm period (circa 4,000 – 6,000 years before present) after the last glaciation profoundly influenced the present day genetic structure of this species. This finding reminds us that human-mediated global climate change may have profound influences on species ranges and economic viability of fisheries stocks.