The history of effective population size and genetic diversity in the Yellowstone grizzly (Ursus arctos): implications for conservation.
2003
Proceedings of the National Academy of Sciences 100(7):4334-4339..
“Protein, mtDNA, and nuclear microsatellite DNA analyses have demonstrated that the Yellowstone grizzly bear has low levels of genetic variability compared with other Ursus arctos populations.” (Abstract)
“A loss of variability is detected, but is much less severe than hypothisized.” (Abstract)
“The viability of the population is unlikely to be substantially reduced by genetic factors in the next several generations. However, gene flow from outside populations will be beneficial in avoiding inbreeding and the erosion of genetic diversity in the future.” (Abstract)
“Genetic diversity has declined slightly in the Yellowstone grizzly bear population since the early 20th century as evidenced by a significant drop in allelic diversiity.” (4338)
“...the loss of diversity and the rate of inbreeding appear to have been less severe than originally hypothisized...” (4338)
“Trend data suggest that the YE population is larger now than it has been in the past three decades (12, 18, 46), implying that Ne is probably >50. If recent evidence that N is at least 400 is accurate, then Ne is likely to be near or >100 (0.27 X 400 = 108). In our opinion, it is unliklely genetic factors will have a substanial effect on the viability of the Yellowstone grizly over the several decades.” (4338)
“If Ne in the NCDE is and remains large, one effective migrant per generation into the YE will maintain the current levels of diversity while the current level of divergence between the two populations will be maintained by two migrants per generation. we therefore argue that one to two effective migrants per generation from the NCDE to the YE is an appropriate level of gene flow.” (4338)
“Because the need for gene flow into the YE is not urgent, we argue that concentrating current efforts on establishing intermediate populations and protecting and restoring interventing habitat are justified. if gene flow does not occur naturally within several decades, however, we argue that translocation should be conducted.” (4338)
“...management should therefore focus on maintaining the YE and NCDE populations at or above their current sizes and encouraging range expansion through natural dispersal and/or reintroduction. Success in these regards will improve the demographic security of the grizzly bear south off the Canadian border as well as address long-term genetic concerns.” (4338)
