There are more than 1,200 bat species in the world, accounting for almost a fifth of all mammal species. Part of the reason for this is that bats are the only mammals with flapping flight, which means that bat colonies can travel long distances and become geographically isolated from each other, splitting into separate species.
But a 2011 study at the University of Massachusetts suggested that their diversity might also be because the diets of different bat species tend to be highly specialised. This means that if a genetic mutation causes, for example, a small change in the shape of the skull or the bite force of the jaw, a bat might be able to eat a new type of fruit or insect that other bats in the area can’t handle.
This gives a big selective advantage to the descendants of this bat, and the mutation spreads. Within an evolutionary short time, the population has split into two groups and another bat species is born.