Why are vampire bats the only mammals that are obligate blood feeders?
Vampire bats have many unique adaptations that make them the only mammals that are obligate blood feeders. A key factor is the presence of anticoagulants in their saliva. Burton Lim, Assistant Curator of Mammalogy at the ROM, and Maddy Foote, a recent Master of Science graduate, have applied to Canada’s Genomics Enterprise to sequence the complete genome (approximately two billion DNA sequences) of two species of vampires that prey primarily on birds, in order to study the evolution of the enzymatic proteins involved in their specialized diet. The genome of the common vampire bat (Desmodus rotundus), which consumes mainly mammalian blood, was sequenced last year by a lab in Denmark. Of the more than 1,400 species of bats, only three are sanguivores (blood feeders), and they occur in tropical Central to South America.
They are also researching the potential discovery of a fourth vampire-bat species. During fieldwork in 2014, Lim and his Peruvian colleagues caught one from the poorly studied dry Pacific coast of South America. Preliminary genetic analysis has identified it as a population distinct from others in Central America and South America east of the Andes. To confirm this difference, Lim and his colleagues are collaborating with researchers in Chile to acquire samples to test the extent of variation at the southern extreme of its distribution.
Genomic-level data will help in finding the origins of the genes responsible for stopping the clotting of blood and provide insights into the evolution and biodiversity of vampire bats. Were these anticoagulant proteins already present in their most recent common ancestor, which enabled sanguivory? Or are they a more recent adaptation to a diet of blood-feeding on birds and mammals?