A shipment of juvenile parrots arrives in Canada, and although the birds are too young to be identified by sight, genetic material from a feather reveals that they are endangered Amazons that have been smuggled in. Blood from Eastern Massasauga Rattlesnakes shows that the genetic make-up of populations in close proximity is more highly differentiated than was ever imagined — posing serious implications for recovery plans to relocate members of the threatened species to new slithering grounds.
Analyzing and comparing the genetic make-up of plants and animals not only improves assessments made using traditional methods, but also yields information that is otherwise inaccessible. Once too labour-intensive and expensive for regular use, molecular techniques have been made more widely available in recent years due to refinements in laboratory techniques, improvements in computer power, and lower equipment costs. Environment Canada is working closely with university labs and other partners to apply genetic techniques to wildlife conservation — in such areas as population monitoring and conservation, studies of the impact of toxic contaminants, and the investigation and prosecution of wildlife crimes.
Deoxyribonucleic acid (DNA) is the principal constituent of genes, and is found in the cells of living organisms — including components of blood, skin, hair, nails, feathers and eggshells. DNA molecules are made up of a linear sequence of compounds called nucleotides, and form a long, continuous strand inside a structure called a chromosome. The unique sequence of the nucleotides in a chromosome determines the hereditary characteristics of an individual — from its species and sex, to traits such as eye colour. Each gene occupies a particular location on the DNA strand, making it possible to compare the same gene in a number of different samples.
Different areas of DNA accumulate mutations at different rates. Some genes are so basic to the functioning of the individual that most changes or mutations will affect survival and will not be passed on to the next generation. Other genes for more superficial traits can accumulate mutations more quickly, and some areas of DNA are “non-coding” and can have very rapid rates of change. Differences in mutation rate are like the hands of a clock — each is useful for different time scales. Differences in mutation rate can allow comparisons of very ancient divisions, all the way up to the very recent divisions between parents and offspring.
Part of a DNA strand.
Many genetic techniques involve a process in which short segments of a DNA strand are replicated to produce a sufficient quantity of material for analysis. These segments can then be examined for differences in size between individuals or for differences in the actual nucleotide sequence of the segments. In contrast, other techniques cut DNA into segments using enzymes, and certain of these segments are radioactively tagged to create a visual pattern on X-ray film. DNA fingerprinting is the most popularly known of these techniques. The fingerprint of one individual can be compared to other fingerprints to determine if two or more samples originated from the same individual, or to identify close relatives, such as parents and siblings.
In the area of population monitoring and conservation, genetic techniques are used to link individuals found in separate areas, determine migration patterns, establish the geographic bounds of populations, estimate gene flow among populations, profile the genetic diversity and sexual make-up of populations, and manage captive breeding programs and translocation and reintroduction efforts. Genetic information can also be used to determine if small populations carry a unique component of overall biological diversity.
Analyzing DNA is particularly useful in studying organisms that are rarely encountered by humans, including snakes, frogs, and some species of birds. A recent genetic survey of Spotted Frog populations in the Pacific northwest revealed the existence of two distinct species where one had originally been supposed. The name Oregon Spotted Frog now refers to three isolated populations in the Fraser River lowlands of British Columbia and 10 in the United States. About 79 per cent of this species has been lost across its range, and Canadian populations number fewer than 300 individuals.
Genetics are equally useful in discerning species and subspecies with similar external characteristics. For example, there are as many as 100 subspecies of Canada Geese — many of which cannot be reliably distinguished by sight. Although the Atlantic population recently underwent a 75-per-cent decline, the trend was initially camouflaged by an exponential increase in the number of birds on common wintering grounds. Environment Canada is currently collaborating with Michigan State University to obtain genetic profiles of all the subspecies in Ontario, a project that will take up to four years to complete. This will enable biologists to use wings and tailfeathers provided by hunters to monitor individual populations more closely, and adjust bag limits as required.
Recent genetic studies of the endangered Eastern Harlequin Duck showed that birds formerly thought to be members of a single population are actually from two distinct populations that breed and winter at different sites, and do not naturally mix. DNA was also used to determine that the Dolly Varden and the Bull Trout are distinct biological species — information that was instrumental in identifying the watersheds used by each and in planning the restoration of fish habitat in northern British Columbia. Genetic techniques also recently proved that the small population of wolves in central Ontario’s Algonquin Provincial Park are not related to the Grey Wolf — as has long been thought — but are actually closely related, if not identical, to the highly endangered Red Wolf. All of these findings have serious implications for the conservation of biological diversity.
Genetic techniques are also used to test for genetic damage or the altered regulation of genes caused by contaminants such as pesticides — effects that might otherwise be invisible. Some contaminants, called endocrine disrupters, induce the expression of genes in the inappropriate sex. Environment Canada’s National Wildlife Research Centre has devised a way to identify such substances by measuring their ability to artificially induce the expression of a gene linked to a particular sex — in this case, the egg protein vitellagonin, normally found only in female birds. Another study is using DNA analysis to determine the roles of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and heavy metals in the creation of heritable mutations in Herring Gulls nesting near steel industries.
DNA analysis is also used to ensure that foods, such as caviar, do not contain products derived from plants or animals that are protected under the Convention on International Trade in Endangered Species.
Wildlife enforcement officials in Environment Canada also use genetic markers to identify species from forensic material, link individuals to a geographic area, and determine parentage and sex. A major impediment to identifying species of origin, however, is the lack of a reliable DNA database to provide baseline references. To help build up such data, biologists are working with scientists at Trent University in Peterborough, Ontario, to develop DNA markers for species of ducks and other waterfowl. The markers have been used to detect illegal game in restaurant food — even in cases where quantities of the game are less than one per cent of a meat mixture. DNA analysis is also used to investigate cases where illegal hunting practices are suspected, but the bird carcasses have been plucked and decapitated, making identification otherwise impossible.
Another major project is a collaboration with the United States Fish and Wildlife Service Forensic Laboratory in Ashland, Oregon, to identify sturgeon species from caviar samples. The Ashland lab has already established species-specific DNA sequences for most of the 23 species of sturgeon, to identify cases where eggs from Short-Nosed Sturgeon and European Sturgeon — both protected under the Convention on International Trade in Endangered Species —have been illegally imported, and to ensure that the necessary permits have been obtained for caviar from other species. In a recent case, a DNA analysis revealed that a shipment of “sturgeon” caviar was actually a mixture of herring and other fish eggs, which had been coloured and reshaped.
To prevent illegal trade in Gyrfalcons and Peregrine Falcons, Environment Canada is collaborating with Canadian breeders to establish a DNA bank of genetic profiles of specimens in captivity. This will enable enforcement officers to tell if chicks in trade are actually the offspring of registered breeding pairs, or if they have been taken illegally from the wild.
Although most of Environment Canada’s genetic projects are still at the pilot stage, the successful use of DNA analysis for a wide range of purposes related to wildlife management prompted the Department’s Canadian Wildlife Service to conduct a complete review of current and potential applications. The review recommends that, while genetic techniques are still fairly expensive and labour-intensive compared to traditional methods of obtaining species information, there are many instances in which their use would greatly improve wildlife management efforts. It also encourages the pursuit of more partnerships with university labs and other facilities to build up the baseline genetic data that wildlife enforcement officers need to identify and prosecute people involved in the illegal hunting or trade of species at risk.
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