The genes behind the wings: Massive study rewrites bat family tree
A greater horseshoe bat in flight. Bats are Earth’s only flying mammals. In addition to flight and other remarkable capabilities like echolocation and disease resistance, bats are an important part of many ecosystems that humans rely on. Arizona State University and the Earth BioGenome Project contributed to a landmark study into bat origins and genomics that generated the first robust evolutionary framework to investigate the genes behind these traits. Photo by Daniel Whitby
Story highlights
- ASU contributed to the largest combined bat genome and fossil study ever undertaken that rewrites the origins and family tree of bats.
- The genomic resource built for this study gives scientists the first robust evolutionary framework to investigate the genes behind bats’ remarkable health capabilities and biological adaptations like flight and echolocation.
- This work could eventually inform research into human aging, immunity and disease resistance.
Bats may have a new hometown — and you might be surprised where it is.
A massive new study involving Arizona State University researchers is rewriting the bat family tree, suggesting these remarkable flying mammals first took wing in Europe about 65 million years ago before spreading across the globe.
Published today in Nature, the largest combined bat genome and fossil study ever undertaken shows that bats most likely originated in Europe around 65 million years ago before spreading across the world.
The results give scientists a genomic map for how one lineage of mammals evolved powered flight, advanced biosonar, exceptional longevity and unusual disease resistance. The work also serves as a foundation to trace the genetic basis of these traits with relevance well beyond bats.
Harris Lewin, a research professor in the Julie Ann Wrigley Global Futures Laboratory at ASU, contributed his expertise in chromosome evolution and formed a team to reconstruct the ancestral bat genome for the landmark study. He is one of 137 international researchers from 64 countries on the team, known collectively as the Bat1K consortium.
Lewin co-founded and leads the Earth BioGenome Project, an international collaborative effort that has its global coordinating center at ASU. The project aims to sequence, catalog and understand the DNA of living things ranging from tiny fungi to the largest mammals.
Bat1K is one of the oldest and most productive groups of the Earth BioGenome Project collaboration. Lewin says the consortium’s efforts have led to bats having the largest number of genomes sequenced out of all mammal taxonomic groups.
“The results that we have generated for this paper are the foundation for understanding the enormously fascinating biology of these species,” Lewin says.
The evolution of bats
Scientists have struggled for decades to answer some of the most fundamental questions about bat evolution, including where they came from, how bat families are related and how they evolved the unusual traits that set them apart from other mammals.
The Bat1K team assembled the largest collection of high-quality modern bat genomes to date, covering 103 species and representing all 21 currently recognized bat families. These were analyzed along with 44 fossil bats from across the globe to reconstruct bats’ evolutionary history.
Technological advancements and standards pioneered by the Vertebrate Genomes Project, part of the Earth BioGenome Project, have made genome sequencing quicker and more cost-effective — enabling work at this scale and complexity to be possible.
Building this dataset required samples collected over decades from bats all around the world, including representatives of some of the rarest and most unusual bat families found in the most remote locations.
Nathan Upman, an associate professor in the ASU School of Life Sciences and a senior Global Futures scientist in the Global Futures Lab, collected field samples from brown flower bats and Waterhouse’s leaf-nosed bats in the Dominican Republic. The two species are part of a highly varied family of New World leaf-nosed bats that live in Central and South America. Adding these species to the study helps fill in our understanding of the diversity and evolution of bats worldwide.
The team also reconstructed the genome of Vielasia, an early bat ancestor, showing what the first genome of a mammal capable of flight would have looked like.
Fossil evidence uncovers when bats first evolved flight and echolocation — using sound waves and their echoes to navigate and identify objects.
Findings from the fossil bat that lived before the diversification of the species show that flight and echolocation emerged near the origins of bats themselves. This helps explain the extraordinary evolutionary success of bats over the subsequent 65 million years.
The study results also overturn previous hypotheses proposing Asian, African or North American origins, revise the bat evolutionary family tree, and resolve several long-running debates about how the major bat groups are related.
Paleontologist Matthew Jones, an assistant professor in the School of Life Sciences, worked on the Bat1K team that reconstructed the relationships of extinct bats to living bats. He helped analyze nearly 700 physical traits of the 44 fossil bats — many of which had never been studied in this way before.
“Using this data, and the ages and locations of the fossil species, we were able to reconstruct the time and region of the origin of bats and map their spread across the world,” Jones says.
Jones and the team also analyzed physical traits of bats belonging to modern families to provide a comparison to the fossil bats. This was necessary for the analysis to determine how bats’ physical features evolved from ancient bats to modern species.
With more than 1,500 bat species distributed across the globe, bats account for 1 in 5 of all living mammals. They play vital roles in maintaining healthy ecosystems by pollinating plants, dispersing seeds and consuming vast numbers of insect pests.
The new knowledge about bat genomes can help conserve endangered species in their native habitat.
“If you can distinguish which species are in the same or different taxonomic groups, or how they relate to one another, it really helps you to make decisions about how you manage threatened and endangered populations,” Lewin says.
Many bat species also live exceptionally long lives for their size and have remarkable disease resistance. For example, bats carry viruses related to SARS-CoV-2 that make humans and other animals sick but don’t negatively affect bats.
The findings can help scientists understand what viruses each bat species harbors and how their immune systems control them. That in turn helps scientists understand how these viruses jump to other animals and humans as well as how to create more effective treatments and vaccines.
The genomic resource built for this study gives scientists the first robust evolutionary framework to investigate the genes behind these traits. This work could eventually inform additional research into human aging and immunity.
“It is extraordinary, after decades of research and conflicting findings, we finally have a robust phylogenetic tree that we can now use to properly understand how bats’ unique traits evolved,” says Emma Teeling, a professor at University of College Dublin, co-founding director of Bat1K and a senior author on the Nature paper. “We also have the genomes to uncover the molecular basis of these spectacular adaptations and know where the fossil bats fall in this tree.”
About Bat1K
The Bat1K consortium is an international initiative working to generate and analyze reference-quality genome assemblies for all living bat species. This study represents Phase 1 of the project. See more at www.bat1k.com.
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