Although the Greater Sage Grouse recently was denied listing as an endangered species based on current science, questions remain about the genetic viability of, and distinctions between, different populations of this bird. Sage Grouse currently inhabit only 56 percent of their historic range, leaving some populations isolated from each other. FORT scientists recently completed DNA analysis of Greater Sage Grouse sampled across their entire range of 11 states and 2 Canadian provinces using both mitochondrial sequence data and data from 7 nuclear microsatellites. They found that, in general, Greater Sage-Grouse populations follow an isolation-by-distance model of restricted gene flow. This suggests that movements of Greater Sage-Grouse are typically among neighboring populations and not across the species range. This could have important implications if resource management agencies are considering translocations, in that translocations involving neighboring rather than distant populations would preserve any effects of local adaptation. Further, investigators identified two populations in Washington with low levels of genetic variation that reflect severe habitat loss and dramatic population decline. Managers of these populations could consider augmentation from geographically close populations. Another population (Lyon/Mono, Calif.) on the southwestern edge of the species range appears to have been isolated from all other Greater Sage-Grouse populations. This population is sufficiently genetically distinct that it warrants protection and management as a separate unit. In conjunction with large-scale demographic and habitat data, the genetic data presented in this study will provide an integrated approach to conservation efforts for Greater Sage-Grouse.
For management purposes, the range of naturally occurring Trumpeter Swans (Cygnus buccinators) has been divided into two populations, the Pacific Coast Population (PP) and the Rocky Mountain Population (RMP). Little is known about the distribution of genetic variation across the species' range, despite increasing pressure to make difficult management decisions regarding the two populations and flocks within them. To address this issue, scientists at FORT used rapidly evolving genetic markers (mitochondrial DNA sequence and 17 nuclear microsatellite loci) to elucidate the underlying genetic structure of the species. Data from both markers revealed a significant difference between the PP and RMP with the Yukon Territory as a likely area of overlap. Additionally, they found that the two populations have somewhat similar levels of genetic diversity (PP is slightly higher), suggesting that the PP underwent a population bottleneck similar to a well-documented one in the RMP. Both genetic structure and diversity results reveal that the Tri-State flock (Idaho, Montana, and Wyoming)--a suspected unique, non-migratory flock--is not genetically different from the Canadian flock of the RMP and need not be treated as a unique population from a genetic standpoint. Finally, Trumpeter Swans appear to have much lower mitochondrial DNA variability than other waterfowl studied thus far, which may suggest a previous, species-wide bottleneck.
Understanding the population structure of a species is key to developing effective wildlife management strategies. For example, if wildlife managers apply different management strategies on each of two adjacent game management units, but a single population of, say, black bears is represented across both management units, then it is not possible to evaluate either management strategy because the effects are on the population as a whole and not distinguishable between unit boundaries. However, little genetic information is available to assist managers in defining workable "management units" for black bears in Colorado. This project seeks to ascertain population boundaries (if any exist) for black bear populations across the state. FORT geneticists will determine the efficacy of using mitochondrial DNA and microsatellite markers to delineate black bear subpopulations by genotyping approximately 150 individual black bears across 7-10 nuclear microsatellite loci and sequencing a rapidly evolving portion of the control region for each bear. The data will be analyzed using standard population genetic methods.
White-winged Doves (Zenaida asiatica) are a popular game bird in states with large populations of this species, where hunting seasons are regulated to prevent local over-harvest. More knowledge is needed on population characteristics, including population demography in both the Central Flyway and Pacific Flyway portions of the species' range, to set hunting regulations. Information should be specific by age and gender since hunting could overexploit one gender or age class. Gender determination of White-winged Doves based on examination of live birds is difficult. Thus, a rapid and effective method is needed to ascertain gender of White-winged Doves in banding programs, especially those that are likely to result in the capture of large numbers of individuals. FORT geneticists have tested the efficiency of using the length of tail feathers to ascertain gender and have validated this method using molecular sexing techniques.
The Lesser Prairie-Chicken (Tympanuchus pallidicinctus) has one of the most restricted ranges of North American grouse, having sustained marked reductions in suitable habitat over the past 100 years. What remains is a highly fragmented distribution throughout its range. Despite a slowing in the rate of habitat loss, populations have continued to decline range-wide, and the bird is considered a "warranted but precluded" threatened species by the U.S. Fish and Wildlife Service (FWS). FWS managers are concerned that genetic diversity within individual populations might not be sufficient to maintain them. Using mitochondrial DNA sequence and nuclear microsatellite analyses on three Kansas populations of Lesser Prairie-Chicken, a FORT scientist and collaborators at Kansas State University have determined that, despite the current anthropogenic stresses on the species, most Lesser Prairie-Chicken populations have retained relatively high levels of genetic diversity and appear to be relatively well connected. This information is aiding managers in determining the best conservation practices for these birds at local and regional levels.
Understanding how population structure and dynamics affect local and regional populations of a species is important for determining effective management strategies. FORT conservation geneticists are determining the efficacy of using mitochondrial DNA and microsatellite analysis to delineate cougar (Felis concolor) subpopulations across the state of Colorado for the Colorado Division of Wildlife. Identification of female substructuring of the population across Colorado would influence how management strategies are implemented in the state. Evaluating the use of mitochondrial DNA and nuclear DNA as a potential method to delineate populations will help determine whether future efforts are warranted.
Previous genetic analysis of four populations of Mountain Plover (Charadrius montanus) across its breeding range has shown that, despite habitat loss and fragmentation, gene flow among isolated populations has been sufficient to prevent genetic differentiation among populations. However, this previous work only used mitochondrial DNA sequence data to make inferences about population structure. Because mitochondrial DNA is maternally inherited and tracks only female movement, current research has focused on developing molecular markers from the nuclear genome that can be used to quantify both male and female movements. A set of 15 polymorphic microsatellite loci were isolated from Mountain Plover and optimized for use. FORT researchers screened individuals from the same four breeding populations collected previously and again found very little genetic differentiation among locales, suggesting that levels of genetic exchange among populations is higher than once thought.
The Midget Faded Rattlesnake, Crotalus oreganus concolor, is a small subspecies of the Western Rattlesnake that is found in the Colorado Plateau of eastern Utah, western Colorado, and southwestern Wyoming. This subspecies has always been considered to be naturally rare and is protected in Wyoming, Utah, and Colorado. Midget Faded Rattlesnakes exist in very small, isolated groups centered around den sites with few (1-25) individuals, and seasonal movements may be only a few hundred meters. Such natural history traits make these rattlesnakes a sensitive species vulnerable to various human impacts. In addition, the construction of Flaming Gorge Reservoir over 50 years ago divided the population in half and forced them to higher ground. This study investigated the population structure and dynamics of Midget Faded Rattlesnakes, using genetic analyses of microsatellite DNA markers in the lab and radio telemetry in the field. FORT scientists have analyzed the genetic structure of the population as a whole along with localized characteristics of subpopulations around the reservoir. They found significant levels of genetic structure among populations and showed that the Flaming Gorge Reservoir and associated waterways did not pose significant barriers to movement. Additionally, they found that the most genetically distinct populations were those farthest north and the most susceptible to potential impact from human activity.
The need for accurate demographic and relatedness information has been identified as a high-priority need for the management and recovery of the endangered Indiana bat (Myotis sodalis). At the request of the U.S. Fish and Wildlife Service, scientists from FORT and Indiana State University investigated whether this information can be gathered using molecular techniques from non-invasively collected samples such as fecal pellets. This pilot study has shown that DNA can successfully be extracted from single Indiana bat fecal pellets collected from underneath roost trees. (Successful DNA extraction from fecal pellets of related bat species has only been accomplished once before, in a controlled laboratory setting; and in that case, several pellets from each bat were pooled for extraction purposes.) Additionally, FORT geneticists have isolated and developed primers for a suite of highly polymorphic microsatellite loci that can be used not only for unique identification of Indiana bats, but also for population genetics and studies of relatedness. It is likely that some of these new markers will work in other closely related bat species. Finally, study results show that these novel techniques and new markers can be used to gather a variety of data regarding Indiana bats, including information about demographics (e.g., population size, survival rates, and individual movements); social structure (e.g., relatedness of individuals in roost trees); and population structure.