Forget Asia and Africa: bats originated in Europe 65 million years ago
A genomic study of 103 species and 44 fossils places the origin of bats in Europe 65 million years ago and dates the birth of flight and echolocation, in a Nature paper with CSIC participation.
For decades, it was assumed that bats had originated in Asia, Africa or somewhere in the Americas. A new study now calls that idea into question. According to its authors, the lineage arose around 65 million years ago in Europe, from where it spread to colonise the rest of the planet. In other words, the first bat species dates back to the age of the dinosaurs.
The research, the most comprehensive carried out to date on this group of mammals, combines the genome sequencing of 103 species with the study of 44 fossils. The work forms part of Bat1K, an international consortium devoted to gathering genomic information on bats, and has been published in the journal "Nature" (source in Spanish). On the Spanish side, researchers from the National Museum of Natural Sciences (MNCN-CSIC) and the University of Granada have taken part.
Ismael Galván, a researcher at the MNCN, sums up the scope of the study: it is the first time that the genome of a flying mammal has been reconstructed, and this resource offers the scientific community a solid framework for investigating the genes responsible for their most distinctive traits. He explains that this line of research could eventually provide useful information for studies on ageing, immunity and resistance to disease in humans.
Professor Liliana M. Dávalos, of the University of Stony Brook, notes that the method used (jointly modelling the evolution of fossil and living species) makes it possible to do something other techniques could not: to place the oldest group of fossil bats while taking genomic data into account and thus determine when and where the group appeared. The data suggest that the first descendants of that European population dispersed into Africa, forming a Euro-African core from which bats later reached Asia, the Americas and Australia.
Flight and echolocation, present from the very beginning
One of the findings highlighted by the team is that powered flight and echolocation, two features that define the biology of these animals, did not emerge at later stages of their evolution but near the very origin of the group.
The position of the fossil of the genus Vielasia, regarded as an ancestor of modern bats, on the oldest branch of the family tree reinforces that conclusion, which would help explain the evolutionary success of the lineage over 65 million years.
Michael Hiller, of the Senckenberg Institute in Frankfurt, describes the procedure followed: state-of-the-art DNA sequencing techniques combined with computational methods to generate and compare genomes, identify the genes they contain and cross-reference that information with the 44 fossils collected in different parts of the world.
The result, according to Professor Emma Teeling, of University College Dublin, is a robust phylogenetic tree after decades of findings that often contradicted one another.
To assemble the set of samples, the team turned to little-known species found in remote locations: the bumblebee bat from Thailand and Myanmar, one of the smallest mammals on Earth; the Madagascar sucker-footed bat, able to cling to smooth leaves thanks to small suction cups; and the lesser short-tailed bat, native to New Zealand, which uses its folded wings as if they were forelegs to move along the forest floor.
A resource with implications beyond animal biology
With more than 1,500 species distributed around the world, bats represent one fifth of all living mammals. Their role in ecosystems is significant: they pollinate plants, disperse seeds and control insect populations.
On top of that comes a feature of particular interest to biomedical research: their resistance to disease and a longevity that is striking in relation to their size.
Professor David Ray, of Texas Tech University, stresses that the volume of data generated will allow the scientific community to track genomic variation, from changes in a single base to the absence of entire segments in one lineage that are present in another.
These differences, he notes, help to explain in part the enormous diversity of bats that exists today and the origins of their unique traits, a body of work whose relevance, he adds, goes well beyond this group of mammals.
