A study that combines the largest collection of bat genomes and fossil records assembled to date points to Europe as the place where these mammals are believed to have arisen about 65 million years ago. The investigation, published in the journal Nature, also clarifies the evolution of flight and echolocation in bats.
The work involved 137 researchers from 64 countries, under the Bat1K international consortium, and combined genomic data with fossil records to reconstruct about 65 million years of evolution of the only mammals capable of truly autonomous flight.
The team analyzed genomes from 103 species, representing the 21 bat families currently recognized, and cross-referenced this information with data from 44 fossil species from various regions around the world.
The results point to a European origin for bats, contrary to previous hypotheses that suggested origins in Asia, Africa or North America. The earliest bats would later have reached Africa, forming a Europe-Africa axis from which they dispersed to Asia, the Americas and Australia.
“Bats have dominated the nocturnal skies for about 65 million years, but determining where they first took flight has been more difficult to clarify,” says Suzanne Hand, a paleontologist at UNSW Sydney, quoted in a press release.
“Advances in genomic sequencing and computation now allow us to compare and combine DNA data from modern bats with the fossil record in ways that were not previously possible. This has provided us with a much clearer picture of the evolutionary tree of the first bats and points to Europe as the place where they first flew.”
One of the data contributing to the reconstruction of the evolutionary history is the fossil Australonycteris, found in Murgon, southeastern Queensland, Australia. At about 55 million years old, it is only slightly younger than the oldest fossils identified in Europe.
“Although we now know that bats originated in Europe, one of the oldest bat fossils in the world – Australonycteris, found in Murgon, southeastern Queensland – is 55 million years old, being only slightly newer than the European fossils,” explains Hand.
This record suggests a rapid dispersal of the earliest bats after acquiring the ability to fly. In the Oceania region, the remaining oldest-known fossils are considerably younger, with about 16 to 18 million years, and were found in St Bathans, Central Otago, New Zealand.
Flight and echolocation likely emerged early
The study also provides new clues about the origin of echolocation, a capability that allows bats to navigate and search for food through the emission and detection of sounds.
The position of the French fossil Vielasia, analysed by Suzanne Hand in 2023, in one of the oldest branches of the bat evolutionary tree indicates that echolocation arose before the diversification of modern bats.
Thus, the results suggest that autonomous flight and echolocation, two of the most striking features of these animals, were already present in a very early stage of the group’s evolution.
“As Australian fossil bats are among the earliest recorded and preserved – about 55 million years old – they provide extraordinary information and empirical evidence about when, where and how flight and echolocation evolved in mammals,” says Hand.
The researchers also reconstructed the genome of the common ancestor of today’s bats, allowing an approximate representation of the genetic characteristics of the first mammal capable of autonomous flight.
A Foundation for Studying Longevity and Disease Resistance
In addition to clarifying the evolution of bats, the new genomic database could help investigate some of the traits that distinguish these animals. Many species exhibit unusually long lifespans for their size and considerable resistance to a range of diseases.
The researchers believe that understanding the genetic mechanisms associated with these traits could, in the future, contribute to studies on aging, immunity and disease resistance in humans.
“Bats constantly surprise us. They are one of the greatest experiments of evolution. This extraordinary genomic resource, the result of years of international cooperation under Bat1K, finally allows us to understand how their extraordinary biology evolved,” says Sonja Vernes, from the University of St Andrews and one of the founding directors of Bat1K.
Bats account for about a fifth of all mammal species currently in existence. They also play important roles in ecosystems, notably through the pollination of plants, seed dispersal and consumption of large quantities of insects.
The research also reveals that the evolutionary history of bats is more complex than previously thought. Different regions of their genomes and even different chromosomes bear signs of distinct evolutionary relationships, a pattern that researchers associate with episodes of gene flow between lineages during the early phases of the group’s evolution.
However, a region of the X chromosome has preserved a signal of the true relationships between species and was decisive in resolving decades of divergences in reconstructing the evolutionary tree of bats.
