The genome sequence of the Yangtze River dolphin, or baiji, is reported this week in Nature Communications. The study highlights genes that are likely to have been involved in the dolphin’s adaptation to aquatic life and may help to explain the reasons behind its recent extinction.

The baiji (Lipotes vexillifer) is one of four known species of river dolphin in the world and is now recognised as functionally extinct. It is believed to be the first cetacean to be driven to extinction by human activity. Guang Yang and colleagues sequence the genome of a male baiji, and resequence three additional baiji genomes, to better understand the evolutionary adaptations of cetaceans and the genetic basis underlying its recent demographic decline.

Through a comparative genetic analysis with other mammals, the authors provide evidence for the evolution of genes important to life in water, such as smell, taste, vision, hearing and brain expansion. Despite evidence for a population bottleneck ten thousand years ago, the results of the study suggest that the eventual extinction of the baiji was not a genetic consequence and thus implicates the negative impact of human interference on the Yangtze River. This study provides a valuable resource for studying the evolution and conservation of aquatic mammals.