Cited research: Mol. Ecol. doi:10.1111/j.1365-294X.2010.04647.x (2010)

Mobile marine animals such as dolphins seem unlikely to form subpopulations, as there are no obvious physical barriers between them. Nevertheless, cetaceans do congregate in different parts of the ocean, creating distinct genetic groups.

To find out how environmental factors influence this segregation, Martin Mendez of Columbia University in New York and his co-workers carried out a genetic analysis of the franciscana dolphin (Pontoporia blainvillei), which lives in the western South Atlantic. They studied tissue samples from 275 individuals from six points along the Argentinian coast, and examined ten years of environmental data on these dolphins' ocean haunts gathered by remote sensing.

The team found that differences in nuclear DNA structure between subpopulations correlated more strongly with differences in local environmental conditions — such as chlorophyll levels and turbidity — than with geographical distance. E.M.