Where did bats come from? Family tree drawn from huge genetic study

Diaemus youngi, a bat found in Suriname in South America, is one of the species contributed to the Bat1K project by Burton Lim at the Royal Ontario Museum, who co-authored the new study of bat genomes published Wednesday. (Burton Lim/Royal Ontario Museum)Social SharingScientists say they've settled the debate about where bats came from and uncovered what early bats were like, thanks to a huge study of genomes from all 21 modern bat families and a comparison to dozens of fossil bats.

The earliest bats most likely evolved in Europe around 65 million years ago, reports the new study published Wednesday in the journal Nature.

Previously, scientists have debated whether they could also have come from Asia, Africa or North America – and fossils were too sparse to answer that question, said Sonja Vernes, senior author of the paper and director of the Bat1K consortium behind the study.

"Because bats are flying … they've been dispersing all over the world and crisscrossing the planet for, you know, millions of years," added Vernes, a professor at the University of St. Andrews in Scotland, speaking to CBC News from Cyprus where she is studying tiny bats called Miniopterus in local sea caves.

The researchers learned more about the earliest bats by sequencing genomes from 103 bat species, analyzing their traits and genes, comparing them to 44 bat fossils and using what Vernes called a "complicated advanced computational method." 

They learned ancient bats had 26 chromosomes and first evolved around 65 million years ago, after the dinosaurs died out and many mammals started diversifying. 

Palaeochiropteryx tupaidon, found in Germany, is a fossil bat that lived 47 to 48 million years ago. The new study found that bats originated in Europe about 65 million years ago, and evolved flight and echolocation very early on. (Matthew F. Jones)They developed echolocation early on. The analysis shows that the fossil bat Vielasia, which lived 50 million years ago and has a bone structure that showed it could echolocate, was part of the oldest branch in the bat family tree.

Today, there are 1,500 species of bats around the world, representing about a fifth of living mammal species, and the new family tree shows exactly how their 21 families are related to one another.

Now that the data has been made publicly available around the world, Vernes said she is "really excited to see what we can learn from their genomes to apply to human health."

Bat researchers have long wondered why bats are so extraordinarily long-lived for their size (up to 40 years, compared to only a couple for similar-sized animals like mice) and unusually resistant to viral diseases. Studying their genomes could help reveal their secrets.

"Maybe it'll help us produce bat-inspired health-care treatments," Vernes said, although she acknowledged that wouldn't be in the immediate future.

A pale spear-nosed bat is photographed in flight in the lab of Sonja Vernes at the University of St. Andrews in Scotland. Vernes is a senior author of a new study of bat genomes and fossils. (Brock & Sheri)The reason she personally likes bats so much is because they're one of the only mammals where the babies have to learn how to speak from adults. "And so that makes them like humans." Her own research, based largely on pale spear-nosed bats in her lab that are originally from Trinidad and Tobago, is on how bats learn vocal communication.

She and Emma Teeling at University College Dublin decided 10 years ago that they wanted to sequence the genomes of every bat on Earth "because they're such amazing creatures."

"We could harness the power of genomics to understand what makes bats special and what they do for the planet."

They built a collaboration of 600 researchers around the world, including 137 from 64 countries who are co-authors on the new paper, including some Canadians.

Assistant curator of mammalogy and bat expert Burton Lim is pictured at the Royal Ontario Museum, in Toronto, on Nov. 16, 2021. (Evan Mitsui/CBC)They include Burton Lim, assistant curator of mammals at the Royal Ontario Museum, who supplied about a third of the samples for genome testing in the study, mostly species from tropical South America and Southeast Asia that he collected using mist nets hung over rivers and the entrances of caves. 

His favourites were sheath-tailed bats of Central and South America, which can adjust the membrane between their hind legs to help them manoeuvre during flight. 

They're harder to net because they're high-flying. 

"So it took me a while to catch them all," Lim recalled. But in the end, he added 25 or 26 species to the ROM's collection.

While many bat researchers store their specimens in ethanol, Lim said the ROM puts them straight into liquid nitrogen, which allows the genetic information to be preserved much better. 

Lim said bats may get a bad rap, but they do a lot of good for the world, from pollination to seed dispersal to eating crop-damaging insects. A 2024 study even showed when bats decline, human infant mortality increases. 

Lim hopes that making so many bat genomes available for research will spur other studies looking at the genetics behind things like echolocation and "find out how the [bats] actually do a lot of this stuff that makes bats unique as far as mammals go."

Similar big genome projects are underway for other species, and had previously been done for primates. University of Montreal anthropology professor Joseph Orkin was part of that study, and has found the primate genome data useful in his own research on lemurs. 

He said the bat study "looks really exciting," and such a huge database could provide the backbone for answering big questions about bat evolution.

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