• Goal = use 13 microsatellites and mitochondrial DNA on historic samples to look at how much genetic diversity has decreased over time
• ABSTRACT = Loss and degradation of habitat affects a population’s genetic diversity and structure, effective population size, and gene flow. Use of historic samples allows genetic studies of declining species to be extended back in time, putting contemporary levels of genetic variation into context and determining if genetic patterns have changed over time. The greater sage-grouse is a lekking species that has declined by 66%-92% during the last 35 years in Canada. Our goals were to determine if genetic diversity had declined over time, if birds in Canada had become more genetically structured with increasing habitat fragmentation, if there was evidence that a genetic bottleneck occurred, and to estimate current and past effective population sizes. We sampled Canadian sage-grouse over three time periods (1895 - 1965, 1965 – 1991, and contemporary [1998 – 2007]) and genotyped 2,163 birds at 13 microsatellite loci, including 238 birds collected before 1991. We found high genetic diversity during each time period with no decline through time. Genetic diversity did not greatly differ from values predicted by simulations using genotypes from pre-1965 and lek count data. Genetic structure did not change and there was no evidence of a genetic bottleneck. Effective population size decreased with time and was estimated at 46.8 – 93.6 individuals for the contemporary time period. However, estimates of the effective number of breeders were larger. Together, our findings suggest that more birds are breeding than expected for a lekking species and Canadian sage-grouse are part of a genetically diverse panmctic population.