U study reveals evolutionary traits

DNA barcoding can identify genetic variation within a species.

by Brent Renneke

A University of Minnesota study that took place in Papua New Guinea identified important evolutionary information using a process that revealed diversity within a species. Widely known for its ability to identify species, DNA barcoding was used to demonstrate its effectiveness in revealing important evolutionary traits within a species. âÄúYou can get more information than just the species identity,âÄù said George Weiblen, associate professor in the department of plant biology. âÄúYou can also find genetic variation within a species that can tell you something about the animal.âÄù DNA barcoding, which looks at a short identifier of a speciesâÄô DNA, was used on Lepidoptera, an order composed of moths and butterflies. The study was conducted across a large geographic region and across different host plant species that the Lepidoptera fed on as caterpillars, according to Weiblen. The study revealed the amount of dispersal for some members of the family. Dispersal was surprising, according to Weiblen, who said some moths from Papa New Guinea with near-identical DNA barcodes were found in Queensland, Australia, which is thousands of miles away. Though how these moths are traveling these distances is still a question, Weiblen said that using DNA barcoding is one of the best ways to obtain this kind of data. âÄúItâÄôs a whole lot easier to identify these patterns with a DNA barcode than it is to put a radio transmitter on a 2-inch wingspan, which obviously cannot even be done,âÄù Weiblen said. Understanding migration patterns can be used to identify the origin of invasive species like the emerald ash borer in Minnesota, Weiblen said. âÄúWe know the emerald ash borer comes from Asia, but Asia is a big place,âÄù he said. âÄúKnowing exactly where in Asia provides information that could be vital in coming up with a strategy to combat it.âÄù Knowing the source of invasive species like the European buckthorn, which has been found in Minnesota, could provide a key to keeping them under biological control, according to Weiblen. âÄúSome pests or pathogens are keeping it in check in Europe,âÄù Weiblen said. âÄúWe could learn what ecological factors are holding it back in its native place.âÄù Scott Miller, curator of Lepidoptera at the Smithsonian National Museum of Natural History and a researcher in the study, said DNA barcoding receives the majority of its funding from organizations that deal with these exact problems. Along with migration patterns, the evolution caused by the diet of the Lepidoptera is evident in DNA barcoding, Weiblen said If caterpillars mate on the plant where they feed, Weiblen said, the isolation of the caterpillarâÄôs mating could result in a unique barcode. If insects constantly switch host plants, DNA barcodes would not vary in the population because the seclusion in mating does would exist. Weiblen said the Lepidoptera of the region varied in both migration and diet. âÄúIt is no surprise that the tropical forest is a complex place with different organisms doing different complex things,âÄù he said. The study also serves as another tool for identifying species, Miller said. âÄúWe try to get as much information as we can,âÄù he said. âÄúThink of this as an integrative approach to taxonomy.âÄù The DNA barcoding of the Lepidoptera looked at a sequence of DNA that was strategically chosen, according to Miller. The sequence exists universally in the animal kingdom, Miller said, and the short length of the sequence makes it more cost effective and allows the sample to be degraded like a forensic sample or a dead insect. âÄúWhen we first started using it, it ended up being a lot more useful and universal than we ever thought,âÄù Miller said. The sequence was recommended for use by Paul Hebert, director of the Biodiversity Institute of Ontario. Hebert said because the research in Papa New Guinea used the barcode, he was able to compare it to the Lepidoptera he was analyzing in Australia at the same time. âÄúIf I had been working in one region, and they were working in another, we would not have been able to say anything about the variation between the two,âÄù Hebert said. Miller said the widespread use of the sequence allows researchers to work individually and still contribute to an international effort. âÄúWhen we were not using the same gene in barcoding, our work wasnâÄôt really adding up to anything,âÄù Miller said. âÄúWe can now do our own studies and still have a library that adds up to something with great value.âÄù