Niche diversification follows key innovation in Antarctic fish radiation.

Antarctic notothenioid fishes provide a fascinating evolutionary laboratory for the study of adaptive radiation, as their diversification is linked to both isolation in an extreme environment and a key innovation that allows them to exploit it. In this issue of Molecular Ecology, Rutschmann et al. (2011) evaluate how dietary niche differences have evolved in notothenioids: rarely, or repeatedly in multiple lineages. The authors use stable isotopes to measure species’ use of benthic vs. pelagic resources and map resource use onto a molecular phylogeny. Their findings indicate that pelagic diets have evolved in multiple lineages in at least two families, indicating that dietary niche diversification has occurred repeatedly and in parallel.