Irish-led research has uncovered a previously unidentified group in the bat family tree, and suggests they should be monitored for emerging viruses.
Sometimes in science, you go looking for one answer and find another, unexpected one along the way.
That’s what happened when an international research consortium led by Prof Emma Teeling from University College Dublin (UCD) sought to figure out whether two closely related types of bats were in the same family.
While answering that question (spoiler alert: they aren’t in the same family), the researchers also found a whole new sub-grouping of bats, and the tiny mammals could hold clues about viruses that cause problems for humans.
Family ties among bats
The findings arose from a project spearheaded by Teeling, which looks to map out the relationships between bat species based on their evolutionary relationships. While traditional methods of classifying animals leans heavily on their morphology (or shape and appearance), Teeling uses an approach called comparative phylogeny, which compares the DNA of different species, using it as a telescope back in time to see how related they are.
She and then-MSc student Nicole Foley in UCD were particularly interested in finding out whether Old World leaf nosed bats and their relatives the horseshoe bats were closely enough related to be considered as the same family, or if they were a little too distant for that classification.
As well as settling a long-standing scientific debate, there was a public health impetus for knowing more about the horseshoe bats and their extended relatives, notes Teeling.
“From a human health point of view, these (horseshoe) bats are important, as they are considered as the original source population for the emergence of the coronaviruses SARS and MERS, (which are) fatal to humans but apparently benign to bats,” says Teeling. “If we want to try and understand where these viruses are coming from, we need to know the evolutionary history of these host organisms.”
To check out the family ties between the Old World leaf nose and horseshoe bats, the UCD researchers collaborated with researchers in Australia, Germany, Madagascar, South Africa, Thailand, USA and Vietnam, collecting bat tissue samples and sequencing and comparing 19 genes from the mammals.
They mined into the genetic data to map out the bats’ evolutionary relationships, and used bat fossils to uncover when and where different groups of bats arose. The results, published in Molecular Biology & Evolution, showed that the Old World leaf nosed bats are sufficiently different to the horseshoe bats to classify them as separate families.
But there was more to discover. Within the Old World leaf nosed bats there was another, molecularly distinct family of bats previously unrecognised by science, which these researchers named the “Rhinonycteridae”, as first author Foley explains.
“When we first saw how different the Rhinonycteridae were we couldn’t believe it,” she says. “But, as the results from more and more analyses came pouring in, it became obvious that these bats were indeed very different. They are separated from their closest relatives by 39m years, are genetically very distinct and when we took a closer look at the museum specimens, they even look different. We were convinced.”
Virus clues from bats
Foley also emphasises how important it is to understand the evolutionary pathways of bats.
“Bats and viruses have evolved together over millions of years,” she says. “Emergent coronaviruses like SARS and MERS are becoming a global problem and the family tree of these bats can be used as a roadmap to enable better monitoring and surveillance for future outbreaks of these deadly viruses.”
Teeling would like to see the newly identified Rhinonycteridae family sampled for viruses, because they may be a sentinel for outbreaks that affect humans.
“This is an ancient family of bats that would typically not have been picked to survey as the potential reservoir for coronavirus,” she says. “They would have been overlooked. But our phylogenetic findings are saying we need to start surveying them more.”
This research has been supported in part by Science Foundation Ireland, an IRCSET-Marie Curie International Mobility Fellowship in Science, Engineering and Technology, and the European Research Council, and received support from both the European Community Research Infrastructure Action SYNTHESYS project and Vietnam National Foundation for Science and Technology Development (NAFOSTED).
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