Vampires with genetic defects - Comprehensive genome analysis sheds light on nutrition and evolution of vampire bats

© Brock Fenton

Vampire bats live up to their name: they feed exclusively on the blood of other vertebrates. But how do they cope with this one-sided diet? An international study has now been published in the journal Science Advances, which was led by scientists from the LOEWE Center for Translational Biodiversity Genomics in Frankfurt and the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden. In it, the vampire bat is shown to lack thirteen of the genes found in other bat species. Although the DNA segments of these genes are still found in the vampire bat, the genes themselves have been destroyed by mutations, which means that their function has been lost. Researchers found this out with the help of a newly sequenced genome of the common vampire bat (Desmodus rotundus) and a broad comparison of the genomes of 26 other bat species. 

Gene loss played a fundamental role in adapting to the blood-only diet of vampires. In other animals, two of the defective genes are responsible for the release of the blood sugar-regulating hormone insulin. Vampire bats, on the other hand, only produce very little insulin and have apparently lost the affected genes because their bloody food contains little sugar. While blood is low in carbohydrates and fats, the high iron content poses a major challenge: on average, vampire bats consume around 800 times more iron than humans do. "We assume that the evolutionary loss of this gene is probably an adaptation to the iron-rich blood diet," reports Moritz Blumer from the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, the first author of the study.

Another important finding of the study: the loss of another gene could have influenced the evolution of certain cognitive abilities in vampire bats, the scientists suspect. In vampire bats, for example, a gene is defective that normally breaks down a metabolic product in the brain. This determines cognitive performance and social behavior. A higher concentration of this metabolite can promote memory, learning and social behavior, as suggested by several studies in other mammals. Vampire bats have exceptional memory and social behavior compared to other bat species. Thus, they share blood with other starving individuals, primarily those who have helped them in the past - a skill that requires very good long-term social memory.

"But adaptations to this unique diet are not only due to the loss of genes," says study leader Michael Hiller, Professor of Comparative Genomics at the LOEWE Center for Translational Biodiversity Genomics. In addition to the common vampire, there are two other vampire bat species whose genomes Hiller's team is currently sequencing. “Our goal is to get a complete picture of the genomic changes in all three vampire bat species. And there is still a lot to learn!” says Hiller.