Naturwissenschaften doi:10.1007/s00114-008-0446-0 (2008)

Credit: N. GORDON/OSF/PHOTOLIBRARY

The evolution of the common vampire bat, Desmodus rotundus, included three rounds of duplication of a gene that encodes a salivary enzyme involved in breaking down blood clots. Desmodus laps the blood of mammals. The other vampire bats — Diaemus youngi, which also feeds from mammals but prefers bird blood, and Diphylla ecaudata (pictured), which sticks to birds — have only one copy of a plasminogen activator gene, find David Liberles of the University of Wyoming in Laramie and his colleagues.

Their genetic analysis corroborates established species relationships. DNA sequencing revealed three alternative versions of the gene in Diaemus and four in Diphylla. The four gene copies that Desmodus expresses lack a section called Kringle 2. Its deletion may have aided a dietary switch to mammalian blood.