Bats are critical players in global ecosystems, pollinating plants, dispersing seeds and eating huge numbers of insects. One of only three lineages of flying vertebrates in Earth’s history, there are more than 1,500 bat species living today. But their evolutionary history has been a bit of a puzzle for scientists.
The largest combined bat genome and fossil study ever conducted is now bringing some clarity. Its findings indicate that these flying mammals first appeared in Europe about 65mn years ago, in the aftermath of the mass extinction event that doomed the dinosaurs, before spreading around the world, not in North America, Asia or Africa as previously hypothesised.
The researchers assembled the largest collection of high-quality bat genomes to date, covering 103 species representing all 21 recognized families of bats. They integrated this data with an analysis of 44 fossil bats to decipher their evolutionary history and generate a bat family tree.
They also concluded that, like flight, echolocation - the biological sonar system many bats use to navigate in the dark and catch flying prey - evolved near the dawn of bat evolution.
“I think being able to do both, fly and echolocate, opens up the most amazing opportunities to move into new niches - hunting at night when there’s less competition and fewer predators, for example. Flight got them into the air. Echolocation let them own the night,” said Sonja Vernes, a professor of biology at the University of St Andrews in Scotland and one of the leaders of the study published this week in the journal Nature.
“Echolocation allowed bats to become nocturnal, essentially, and not compete with birds or be preyed on by diurnal (day-active) birds,” said zoology professor Emma Teeling of University College Dublin, another of the study leaders. The study pointed to bats first appearing in Europe about a million years after an asteroid struck Earth 66mn years ago, a calamity that enabled mammals to become the dominant land animals. Relatively soon thereafter, bats reached Africa, making those two continents a hub of early bat evolution, according to evolutionary biologist Liliana Davalos of the State University of New York at Stony Brook, another of the study leaders.
Antarctica is the lone continent bats never inhabited. They now account for more than a fifth of the world’s mammal species. The oldest-known bat fossils date to approximately 52 million years ago. Genome and anatomical data helped identify the origination date of bats.