Genetic Studies Aimed at Protecting Natural Resources

Barcoding technology reveals new information about fish and insects

Prof. Robert Hanner. Photo by Martin Schwalbe.

A forest manager uses a “lab on a chip” to ID insect pests and help head off a devastating infestation. Or fisheries officers employ genetic information to finger an invasive species that threatens native creatures and waters. Helping to restore and protect our natural areas through such scenarios is the ultimate goal of University of Guelph biologists whose DNA barcoding studies have appeared in two high-profile journals this summer.

In a paper in the Proceedings of the National Academy of Sciences (PNAS), Prof. Robert Hanner, Integrative Biology, and his co-authors say their genetic studies suggest much greater fish diversity in North America’s lakes and rivers than earlier believed.

A separate article published in the Public Library of Science One (PLoS One) by departmental colleagues Prof. Alex Smith and Prof. Kevin McCann describes the first use of DNA barcoding to map out “who eats whom” in the spruce budworm food web.

Their separate studies meet in the use of genetic methods to identify creatures to help chart resource management practices in water or on land.

DNA barcoding was developed at U of G to ID living things based on analyzing a telltale bit of genetic material peculiar to each species. Guelph scientists based at the Biodiversity Institute of Ontario are leading worldwide projects to catalogue all species on the planet based on genes and not just what organisms look like.

Hanner and researchers from the University of Laval and St. Louis University tested DNA from more than 750 described species of fishes. Looking at more than 5,000 specimens from collaborators, including several major museum collections, they found that conventional taxonomy may underestimate the total number of freshwater fish lineages by about 28 per cent.

About 900 fish species are known to live in North America. The Guelph biologist says the actual number may be more than 1,000 species.

Commercial and recreational freshwater fisheries in North America are worth billions of dollars and constitute some of the world’s greatest fish diversity. But about 40 per cent of the continent’s fish and freshwater ecosystems are threatened by human activities. “Freshwater ecosystems are among the most imperilled on the planet,” says Hanner.

“We still have trouble identifying species to conserve North American fish,” adds the Guelph biologist, who leads an international barcoding campaign to catalogue the world’s fishes. “It appears that classical North American freshwater fish taxonomy misses diversity in some groups and is artificially creating diversity in others.”

The paper calls for better fish classification and further extends the use of this molecular method for identifying organisms, especially for specimens hard to ID by sight.

Hanner says the PNAS study opens the way to new studies of food webs and the impact of exotic species. He and PhD student Tim Bartley are now using barcoding to analyze stomach contents of fish and learn more about how bass introduced as game fish are affecting native lake trout.

Bartley is co-supervised by McCann, co-author of the PLoS One paper on barcoding of more than 100 species of parasitoid wasps and flies that make up the spruce budworm food web.

The spruce budworm is the most economically important insect in eastern North America. In outbreaks occurring every 30 to 40 years, this pest can cause billions of dollars of damage to forests across the continent. Learning more about “who eats whom” in this complicated food web may help managers better control the budworm and predict flare-ups, says Smith.

Profs. Alex Smith, left, and Kevin McCann. Photo by Andrew Vowles.

The Guelph researchers worked with scientists from the Canadian Forest Service and the University of New Brunswick. They barcoded thousands of specimens of wasps and flies collected between 1983 and 1993 in three New Brunswick forests.

Barcoding helped the researchers to clarify predator-prey relationships among insects, effectively redrawing the food web in greater detail. Says Smith: “We’re adding nodes to the web of life.”

Future research might further refine the web, says McCann. Smith envisions making microarrays – basically DNA on a chip – that would allow managers and scientists in the field to quickly identify species and help protect forests in eastern Canada.

This study grew out of earlier work by McCann on biodiversity and ecosystems, as well as Smith’s use of barcoding to identify tropical insect species in Costa Rica.

Their paper also confirms earlier results showing that more diverse balsam fir forests can better withstand a spruce budworm outbreak than can monoculture stands. Explaining that their results might be used in other ecosystems on land and in water, McCann says: “You want to move away from monocultures. They tend to cause large pest problems, not pest solutions.”