Bugs with barcodes: Trapping blitz in national parks targeted the tiny
Submitted Photo/Yukon News
When we think of the wildlife in Canada’s national parks, it’s moose, bears, snakes, grey jays, trout and chipmunks that come readily to mind. But such animals - those with vertebrae - make up only a small fraction of the creatures that stalk, pounce, graze and browse within park boundaries. Among terrestrial species, arthropods rule.
When it came time to begin a major assessment of life in Canada’s parks, scientists and Parks Canada staff realized that arthropods - creatures with jointed legs, segmented bodies, and exoskeletons rather than vertebrae - could give us a more realistic idea of the biodiversity and health of national parks than the less numerous but more familiar furred, finned and feathered icons of forest and shoreline.
There are over a million species of arthropods in the world, including beetles, ants, spiders, daddy long legs, mites, crabs, centipedes, deer flies and butterflies. “Arthropods have been the least studied and are the most difficult animals to tell apart,” says Kate Perez, field operations lead at the Centre for Biodiversity Genomics at the University of Guelph.
In fact, it’s modern DNA analysis that demonstrates species differentiation more readily and accurately than, for instance, the colour-shade or wing-length measurements of traditional taxonomy.
Barcoding targets one region in a gene that is distinctive for each species. That code, entered in an international data bank, is available to researchers anywhere.
The Canadian National Parks Malaise Program, designed to provide DNA samples for barcoding from all Parks arthropods, was launched in 2012. The following year Perez took the reins of the program, working with colleagues in both the field and the lab to gather, sort and co-ordinate the flood of arthropod DNA and related data that they retrieved from 43 parks across the country (including Kluane, Vuntut and Ivvavik in the Yukon).
By the end of the program in 2015, Parks staff, scientists and students had collected more than 725,000 specimens and identified more than 36,000 arthropod species.
Bruce Bennett, co-ordinator of the Yukon Conservation Data Centre, puts such numbers into an impressive perspective. Until the 1500s or 1600s, there were only about 500 species of plants and animals known to western science. “That is the same number that was known in 500 CE (Common Era),” Bennett says.
For this most recent initiative to expand our species horizons, “national parks were the logical choice,” says Perez. The Centre for Biodiversity Genomics already had a good working relationship with Parks Canada, she explains. And the parks themselves are readily accessible.
The collecting initiative was composed of two major segments. The Canadian National Parks Malaise Program most directly involved Parks field staff. When their day jobs allowed, they monitored Malaise traps: tent-like structures invented by a Swedish biologist named Rene Malaise. These tents are designed to catch flying insects.
For the second segment of the program, scientists and students deployed a variety of other traps in the parks, including simple yet effective devices that collect arthropods (such as those that don’t fly) that the Malaise traps might have missed.
One such device is the pan trap, a yellow dish filled with soapy water. To an arthropod it looks like a flower, so they are drawn to it and fall in. Another strategy, the pitfall trap, is a small cup placed in a hole dug in the ground, almost like a miniature tiger trap. A strolling beetle, for instance, trips over the precipice and plops into the cup also filled with soapy water. Still another device is the flight-intercept trap, which is a mesh wall erected above a pan of - you guessed it - soapy water.
Soapy water is the medium of choice when the collecting dishes are accessible to non-targeted creatures. “We don’t want deer drinking ethanol,” says Perez of another preservative, one used in conjunction with sweep-netting - picture grad students wielding butterfly nets - and Berlese funnels.
A Berlese funnel collects arthropods that tend to avoid light and live in leaf litter and other such cover. Researchers feed the litter into the funnel, where it is subjected to light and heat. As the litter dries, the specimens in it drop down into ethanol.
At the end of each field season during the program, specimens collected by all of these methods were sent to the lab. From the Yukon to the Atlantic provinces, they arrived in Guelph to be removed from their vials, sorted and analyzed.
The first step was to place specimens in a Petri dish. These were examined under a low-power, wide-field microscope. A researcher sorted through the contents by sample size. Tiny ones went straight to analysis. For larger arthropods, only a leg was sent on. Specimens were divided by order - beetle, fly, ant, spider, mite, etc.
The next step was to extract DNA from each sample. A specific genetic region called cytochrome oxidase I is targeted for barcoding animal life because it is the universal and essential last step of an animal’s food oxidation processes.
Perez is excited by the surprising quantity of data collected during the program, especially from the North. Over only one week in Vuntut, Malaise traps captured 2,000 specimens of nearly 500 species. Over four weeks in Ivvavik, the Malaise traps yielded 5,600 specimens of nearly 1,000 species.
“So in remote areas there’s a lot of diversity we didn’t expect,” she says. “In all there were 7,820 specimens from the three Yukon parks of about 3,000 species.”
“Nothing like this has ever been done before,” she adds. The first paper on barcoding DNA was released as recently as 2003.
A number of applications beyond biodiversity assessment have already been found for the technique, extending our knowledge of the millions of creatures with which we share the parks and the planet.
Invasive species, another growing problem in a time of climate chaos and a recklessly expanding global economy, are readily identified through barcodes. Ports, gateways to all sorts of potential plant and animal pests, can be monitored. Even chefs and fish retailers benefit, being able to confirm that a species of seafood is actually what a wholesaler says it is. Traps deployed in mines can reveal industrial effects on local species.
For more information on barcoding and the Centre for Biodiversity Genomics’ impressive role in an international effort to monitor our planet’s biodiversity, check out http://www.biodiversity.uoguelph.ca/
This column is co-ordinated by the Yukon Research Centre at Yukon College with major financial support from Environment Yukon and Yukon College. The articles are archived at http://www.yukoncollege.yk.ca/research/publications/your-yukon