Vampire bats are infamous blood suckers, and they are the only mammals on earth that feed exclusively on blood. It’s a peculiar diet, very low in carbs and high in protein, and biologists have long puzzled over just how these little chiroptera evolved to live on such an unbalanced diet.
Research published in Nature Ecology and Evolution this week showed that to understand the bats, you have to understand their gut microbes as well: to survive on their meagre diet the vampire bats evolved in tandem with their internal microorganisms.
Led by Professor Tom Gilbert at the Centre for GeoGenetics at the University of Copenhagen, the international team of biologists showed that, to understand how a species adapts to its environment, it’s vital to consider both the genetics of the species itself, and of the organisms that live in symbiosis with it — collectively known as the hologenome.
Blood is around 80% water. Of the rest, most is protein, and a fraction of a percent is carbohydrate. Most animals would not survive on blood alone, but vampire bats have evolved specialised immune systems to deal with blood-borne diseases, and kidneys able to manage the high protein levels.
The researchers knew, however, that this wasn’t enough. They demonstrated that vampire bats became blood-suckers through close co-evolution with their own gut microbes.
By examining the bats’ hologenome, including the genetic code of the bats and their gut microbes, the researchers identified that the bats and microbes evolved together to live on blood. The microbes have adapted to help the bats get rid of waste, and compensate for the lack of dietary carbs and fats.
Vampire bats are an excellent species for this research because of their extreme diet, but the researchers state that the results are broadly applicable: to understand the animal, you have to understand its hologneome.
Original Paper: Nature Ecology & Evolution (2018) doi:10.1038/s41559-018-0476-8