Conservation genetics is a relatively new scientific discipline that takes from the more traditional disciplines of genetics and ecology.  In combining these two fields, scientists are able to look at the amount of genetic variation in animal populations, with the intent of piecing together historical and present day factors that may ultimately contribute to extinction, as well as "fingerprint" each individual of the population.  Using genetics enables an virtually unbiased examination of the effects of landscape alteration, such as is occurring with fragmentation, and more specifically, conversion.  By using tissue, hair, blood, or feces, scientists and management agencies are able to compare similarities in DNA sequences.  These comparisons, done with the use of computer programs, give scientist insight as to the amount of gene flow and the degrees of genetic distances between populations.  Sequence data can also be used to identify genetic bottlenecks, or periods of significant reduction in genetic variability caused by drastic change at the community level, such as a large reduction in the number of individuals, or the inability for animals to migrate between populations.

Historically, grizzly bears (Ursus arctos horribilis) of the continental United States, Canada, and Mexico composed a series of interconnected panmictic (freely interbreeding) populations.  Currently, this is no longer the case, as both grizzly bear numbers and habitat availability have been drastically reduced.   Documented decline began shortly after contact with European settlers(Storer and Tevis 1955; Brown 1985), and by the 1920s, they had been extirpated in a large portion of their range.  Currently,four populations exist in the northern Rocky Mountains (Craighead and Mitchell, 1982; Servheen 1989), with the Greater Yellowstone Ecosystem population being one of the largest, holding a significant portion of the remaining 700 - 900 bears (Servheen 1989).

So, how may this bottleneck effect grizzly bears in the Greater Yellowstone Ecosystem?  Researchers have found the amount of heterozygosity (a measurement of genetic variability) of bears in the GYE to be one of the lowest in North America (Paetkau et al., 1998).  These researchers believe that the amount of heterozygosity of the bears in this population, in the past 100 years, has dropped 15-20%, using the values obtained from the nearby Flathead Valley in Montana and values obtained from bears in Alaska for baseline comparison. 

What can be done to ensure the genetic variability of grizzly bears? First and foremost, managers need to ensure that migration between populations is occurring on a regular basis, and that once established in new areas, bears are breeding.   One way to do this is to establish corridors between habitat patches.  Since Yellowstone is a nearly a biogeographic island, surrounded by “hostile” habitat, bears would not benefit from traditional corridors (Schaffer, 1992).  In this situation, successful movement would depend upon the establishment and survival of females in intervening habitat, who would function as a sequence of demographic stepping-stones.  Many scientists and activists, alike, have been in support of the establishment of protected lands reaching from Yellowstone to the Yukon, which would be highly effective for enabling gene flow.  Another method forensuring mobility between populations could be a regular exchange of bears between populations.  Although not occurring in the traditional fashion, human induced movement would at least prevent the populations from undergoinginbreeding depression (reduced fitness to due low levels of heterozygosity).