A new phylogenetic tree based on the genomes of 103 bat species and data from 44 fossils points to Europe as the cradle of bats. Echolocation, too, appears to have arisen early in their evolution.
A large consortium of researchers from around the world has used DNA analyses and fossil data to reconstruct the bat family tree, finding that bats most likely originated in Europe during the late Palaeocene, between approximately 59 and 56 million years ago.
Bat1K consortium
Bats are remarkable creatures. They have evolved a highly distinctive mode of flight, use echolocation, and adapt to local diets in a wide variety of habitats. Several of the more than 1,500 species even live exceptionally long lives with few signs of cancer. Yet the origins of these animals have long remained unclear. Researchers suspected they arose in Africa, Asia, or North America, but this was never conclusively demonstrated. The Bat1K consortium – a large group of researchers from, among other places, Germany, France, England, and the United States – has changed that by developing an entirely new phylogenetic tree. And it shows that bats most likely originated in Europe.
In the Nature paper published by the researchers last week, evolutionary biologist Ariadna Morales and her colleagues show how they managed to circumvent earlier obstacles in constructing a bat family tree. Previous research had been hampered by the fact that the same traits evolved independently in different bat species, by conflicting evolutionary signals from different parts of the genome, and by the limited availability of complete chromosome-level genomes.
Computer models
For this study, the biologists analysed assembled genomes from 103 different bat species, including 42 newly assembled genomes. This gave them coverage of all 21 bat families. Morales and her colleagues also incorporated morphological data from 44 bat fossils from around the world. Using various computer models, they compared protein-coding genes and neutrally evolving regions of the genome, and combined those results with the fossil data.
Following these analyses, the researchers were able to construct a new evolutionary tree. They also reconstructed 26 chromosomes of the common ancestor of bats. The combined analyses revealed that bats most likely originated in Europe as early as the late Palaeocene.
The fossil of the genus Vielasia falls, according to this analysis, on the oldest branch of the family tree. This species most likely already used echolocation – meaning that this trait arose before modern bats diversified. With this information, the researchers hope to unravel in future the genetic origins of echolocation and other distinctive bat characteristics.