News Article | November 2, 2015
The Grizzly bear population in Yellowstone National park is thriving and the genetic diversity remains stable since the 1980s, says a new study by the Interagency Grizzly Bear Study Team. The report says that there is a potential that the bears will continue to thrive in the future. Published in the journal Molecular Ecology, the collaborative study by the U.S. Geological Survey (USGS), Wildlife Genetics International, University of Montana, and Interagency Grizzly Bear Study Team, included 729 bears and it shows that the effective population or the ones passing down genes to the next generation quadrupled over a 25-year period. The report says that the number of Grizzly bears that were passing the genes to their offspring increased from 100 in the 1980s to 450 in the 2000s. The numbers of bears are lesser than the actual population because not all of these animals breed. This means that the Grizzlies in Yellowstone are going towards having the effective size needed for a continuing genetic sustainability and survival. As of 2014, there are an estimated 674 to 839 Grizzly Bears in Greater Yellowstone. However, U.S. Geological Survey estimated the total Yellowstone grizzly population at 757. Gene variations help Grizzlies evolve and adapt in order for them to survive alongside changes in the environment. This is very important especially that the environment faces various predicaments including climate change. "The increase in effective size of the Yellowstone grizzly bear population over the past several decades, with no significant change in genetic diversity, supports evidence of population growth based on traditional surveys," said lead author and USGS ecologist, Pauline Kamath. She cited that their finding is a 'key genetic indicator' of the ability of a population to adapt to future changes in the environment that could affect the animals and their habitat. "This is a key genetic indicator of a population's ability to respond to future environmental change," she added. The bear was listed in the Endangered Species Act in 1975 and multiple efforts were made to help the population of Grizzlies to recover and thrive in the long term. The researchers used several newly available techniques to assess Grizzly population since data on wildlife population are limited due to difficulty in measurement and the long period of time needed for measuring individuals in the population. Thus, this study has shed light on how genetic monitoring is needed to complement traditional demographic-based monitoring. This will provide useful tools for population managers in the present and future in order to accurately estimate the survival rate and population of endangered animals.
Poole K.G.,Aurora Wildlife Research |
Reynolds D.M.,British Columbia Ministry of forests |
Mowat G.,British Columbia Ministry of forests |
Paetkau D.,Wildlife Genetics International
Journal of Wildlife Management | Year: 2011
Non-invasive collection of tissue samples to obtain DNA for microsatellite genotyping required to estimate population size has been used for many wildlife species but rarely for ungulates. We estimated mountain goat (Oreamnos americanus) population size on a mountain complex in southwestern British Columbia by identification of individuals using DNA obtained from fecal pellet and hair samples collected during 3 sampling sessions. We identified 55 individuals from 170 samples that were successfully genotyped, and estimated a population of 77 mountain goats (SE = 7.4). Mean capture probability was 0.38 (SE = 0.037) per session. Our technique provides one of the first statistically rigorous estimates of abundance of an ungulate species using DNA derived primarily from fecal pellets. Our technique enables managers to obtain minimum counts or population estimates of ungulates in areas of low sightability that can be used for conservation and management. Copyright © 2011 The Wildlife Society.
Dumond M.,Environment Canada |
Boulanger J.,Integrated Ecological Research |
Paetkau D.,Wildlife Genetics International
Wildlife Society Bulletin | Year: 2015
Assessing grizzly bears' (Ursus arctos) abundance in the Arctic has been challenging because of the large scale of their movements and the remoteness of field locations. We modified a post sampling method used for wolverines (Gulo gulo) to allow collection of hair samples from grizzly bears in the Canadian tundra. We deployed 1 post/cell in a sampling grid of 393 10 × 10-km cells sampled in 2008 and 2009 for two 14-day sessions in July-August of both years. We then compared density estimates from mark-recapture estimators that used telemetry data from previous years with spatially explicit mark-recapture models that used only genetic detections. Over the 2 years of sampling, we detected 98 female and 81 male grizzly bears. We found that the DNA degradation rate was related to collection interval and the number of days between rainfall events and sample collection. Estimates of density were in the order of 5 bears/1,000 km2. The estimates from the 2 methods were statistically similar, but spatially explicit estimates were more precise than those using radiocollar data. Our results provide the first demonstration of the viability of posts as hair-snagging stations to obtain DNA from grizzly bears, and of spatially explicit mark-recapture methods to estimate population size and density for grizzly bears above the tree line. © 2015 The Wildlife Society. © The Wildlife Society, 2015.
Proctor M.F.,Birchdale Ecological Ltd. |
Paetkau D.,Wildlife Genetics International |
McLellan B.N.,British Columbia Ministry of forests |
Stenhouse G.B.,Foothills Research Institute |
And 15 more authors.
Wildlife Monographs | Year: 2012
Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km 2 of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled withmeasures of genetic distance, isolation-by-distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi-factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population-assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter-area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada-US border area, we found extensive fragmentation that corresponded to settled mountain valleys andmajor highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter-area movements detected were made by male bears, with few female migrants identified. North-south movements within mountain ranges (Mts) and across BC Highway 3 were more common than east-west movements across settled mountain valleys separating Mts. Our results suggest that relatively distinct subpopulations exist in this region, including the Cabinet, Selkirk South, and the decadesisolated Yellowstone populations. Current movement rates do not appear sufficient to consider the subpopulations we identify along the Canada-US border as 1 inter-breeding unit. Although we detected enough male movement to mediate gene flow, the current low rate of female movement detected among areas is insufficient to provide a demographic rescue effect between areas in the immediate future (0-15 yr). In Alberta, we found fragmentation corresponded to major east-west highways (Highways 3, 11, 16, and 43) and most inter-area movements were made by males. Gene flow and movement rates between Alberta and BC were highest across the Continental Divide south of Highway 1 and north of Highway 16. In the central region between Highways 1 and 11, we found evidence of natural fragmentation associated with the extensive glaciers and icefields along the Continental Divide. The discontinuities that we identified would form appropriate boundaries formanagement units. We related sex-specific movement rates between adjacent areas to several metrics of human use (highway traffic, settlement, and humancaused mortality) to understand the causes of fragmentation. This analysis used data from 1,508 bears sampled over a 161,500-km 2 area in southeastern BC, western Alberta, northern Idaho, and northern Montana during 1979-2007. This area was bisected by numerous human transportation and settlement corridors of varying intensity and complexity. We used multiple linear regression and ANCOVA to document the responses of female and male bears to disturbance. Males and females both demonstrated reduced movement rates with increasing settlement and traffic. However, females reduced their movement rates dramatically when settlement increased to >20% of the fracture zone. At this same threshold, male movement declined more gradually, in response to increased traffic and further settlement. In highly settled areas (>50%), both sexes had a similar reduction in movements in response to traffic, settlement, and mortality. We documented several small bear populations with male-only immigration, highlighting the importance of investigating sex-specific movements. Without female connectivity, small populations are not viable over the long term. The persistence of this regional female fragmented metapopulation likely will require strategic connectivity management. We therefore recommend enhancing female connectivity among fractured areas by securing linkage-zone habitat appropriate for female dispersal, and ensuring current large source subpopulations remain intact. The fragmentation we documented may also affect other species with similar ecological characteristics: sparse densities, slow reproduction, short male-biased dispersal, and a susceptibility to human-caused mortality and habitat degradation. Therefore, regional inter-jurisdictional efforts to manage broad landscapes for inter-area movement will likely benefit a broad spectrum of species and natural processes, particularly in light of climate change. © 2011 The Wildlife Society.
Haroldson M.A.,2327 University Way |
Schwartz C.C.,2327 University Way |
Kendall K.C.,U.S. Geological Survey |
Gunther K.A.,Yellowstone Center for Resources |
And 2 more authors.
Ursus | Year: 2010
The Greater Yellowstone Ecosystem (GYE) supports the southernmost of the 2 largest remaining grizzly bear (Ursus arctos) populations in the contiguous United States. Since the mid-1980s, this population has increased in numbers and expanded in range. However, concerns for its long-term genetic health remain because of its presumed continued isolation. To test the power of genetic methods for detecting immigrants, we generated 16-locus microsatellite genotypes for 424 individual grizzly bears sampled in the GYE during 1983-2007. Genotyping success was high (90%) and varied by sample type, with poorest success (40%) for hair collected from mortalities found ≥1 day after death. Years of storage did not affect genotyping success. Observed heterozygosity was 0.60, with a mean of 5.2 alleles/marker. We used factorial correspondence analysis (Program GENETIX) and Bayesian clustering (Program STRUCTURE) to compare 424 GYE genotypes with 601 existing genotypes from grizzly bears sampled in the Northern Continental Divide Ecosystem (NCDE) (FST=0.096 between GYE and NCDE). These methods correctly classified all sampled individuals to their population of origin, providing no evidence of natural movement between the GYE and NCDE. Analysis of 500 simulated first-generation crosses suggested that over 95% of such bears would also be detectable using our 16-locus data set. Our approach provides a practical method for detecting immigration in the GYE grizzly population. We discuss estimates for the proportion of the GYE population sampled and prospects for natural immigration into the GYE. © International Association for Bear Research and Management.