Features
Grad Student Goes to Bat for Research
PhD student combines fieldwork, DNA studies to learn more about what bats eat
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| PhD student Elizabeth Clare made her first forays into bat caves as a youngster. Since then, her research has taken her to Central and South America to study the creatures. PHOTO BY MARTIN SCHWALBE |
BY ANDREW VOWLES
If you want to know what bats eat, do what Elizabeth Clare did: start at the other end. The integrative biology PhD student led a study published this year that combined traditional field techniques with modern DNA identification tools to plumb guano from eastern red bats for clues about their diet.
The study, published in Molecular Ecology, was the first to use DNA bar-coding — a molecular technique for ID’ing species developed by Clare’s co-supervisor Prof. Paul Hebert, director of the Biodi- versity Institute of Ontario (BIO) — to probe remains of prey insects found in bat guano.
Besides yielding much more precise information about bats’ favourite foods than picking over excreted remains under a microscope, the study points a path for wildlife managers hoping to help save threatened or endangered creatures in hard-to-untangle food webs, says Clare.
Find bat guano or its equivalent for other creatures and — as long as you can salvage the telltale DNA snippet from an undigested leg or wing bit — a biologist can match up predator and prey species.
“If they excrete it, we can sequence it,” says Clare, now preparing to defend her doctoral thesis next spring.
She and her co-researchers, including Hebert and co-supervisor Brock Fenton at the University of Western Ontario, found a menu of 127 prey species — 125 insects and two spiders — in bat guano collected in Pinery Provincial Park on Lake Huron.
They were able to find enough genetic material in almost 90 per cent of the prey fragments. After running that DNA through sequencing machines at the BIO, they used the bar-coding database held here at U of G to compare the samples and identified the species or genus for 78 per cent of that material.
The most common menu items were moths and butterflies. But these red bats — a migratory species that may travel as far as Mexico for much of the year — also ate beetles, flies and other things.
Being able to match prey and predator like this is a boon for scientists and conservation managers, says Clare.
“The literature on what bats eat is full of holes. If you’re trying to manage something and don’t know what its food is, it’s a useless plan.”
There was a surprise in the data. She had expected that insects able to detect bats’ echolocation would evade the predators’ hunting strategy. But six out of 10 prey species in the samples had “ears” attuned to bat sonar and still ended up being caught and eaten.
That finding questions long-held assumptions about co-evolution of prey and predator species. Looking for explanations, Clare suggests that particular insects may normally live with other kinds of bats than this migratory species. Or maybe co-evolution so far has offered insects a less-than-optimum way to evade the hunters.
“We have feet for running, but a wolf will still chase us down,” she says.
The researchers collected guano by snagging bats at the Pinery and holding them in bags until they’d contributed their bit for science. (Catching bats at dusk involves a nimble trick: toss pebbles near streetlights and wave mist nets to snare the winged hunters mistaking the pebbles for bugs.)
“They’re quite a beautiful bat actually,” says Clare, referring to images of the creatures with their signature copper-coloured fur. “I think they’re cute.”
This summer, the research team studied little brown bats, which eat mostly aquatic insects. Scientists hope to learn more about how the eight bat species found in Ontario divvy up food resources.
Clare spoke about her work last week in Oregon at a symposium hosted by the North American Society for Bat Research. She was also on the speakers’ roster this week at the Third International Barcode of Life Conference in Mexico.
Bats make up the second largest group of mammals in the world and live everywhere except Antarctica, the high Arctic and a few of the Polynesian islands. There are an estimated 1,100 species of bats, found mostly in the tropics.
As a biology undergraduate at the University of Western Ontario, Clare studied fish during summer research positions. There she learned about bar-coding and discovered a fascination with population genetics and with bats generally. (She first worked on bat feeding habits with a Western colleague.)
Her thesis looks at diversity and genetics of neotropical bats. She has collected and bar-coded species from Central and South America and visited Costa Rica this summer with Dan Janzen, a renowned conservation biologist at the University of Pennsylvania.
Clare grew up in Cambridge, where her parents — “naturalists at heart” — fostered a love of the outdoors, including treks to bat caves. “One of their dreams is to retire and become field assistants for me,” she quips.
Her shared office in the science complex is the one with the decorative bat suspended from the ceiling. On her desk is a mechanical toy bat.
“It was a Valentine’s Day gift from my partner,” she says, referring to Robin Floyd, a post-doc in the department.
The red bat study was funded by Bat Conservation International, Environment Canada, and the Natural Sciences and Engineering Research Council.