Genetic diversity and paternity analysis of endangered Canadian greater sage-grouse (Centrocercus urophasianus).

摘要

Greater Sage-Grouse (Centrocercus urophasianus) are an endangered lekking species that has declined by 66%-92% during the last 35 years in Canada. Sage-Grouse have a lek mating system centered on communal breeding grounds where few males are thought to obtain most matings in a given year and females are believed to mate once. I used 13 microsatellites to genotype 2,519 adults 1,206 offspring sampled between 1998 -- 2007 from 104 leks in Alberta, Saskatchewan, Montana, and Wyoming and 238 historic Canadian birds collected between 1895 and 1991. My goals were to determine the (1) genetic population structure, diversity, and dispersal ability of birds in the proposed northern Montana population, (2) diversity and relatedness of Sage-Grouse in Alberta, (3) paternity, polygamy (males and females mating with multiple individuals), and reproductive variance among individuals in Alberta, and (4) if genetic diversity, structure, and effective population size changed over time in Canada. I determined that northern Montana (northern Montana, Alberta, and Saskatchewan) formed a single genetic population with high diversity and no evidence that peripheral regions were genetically depauperate or highly structured. Both sexes disperse, but males disperse further and more frequently. Within Alberta, diversity was high and relatedness was close to zero for both sexes at the lek-level suggesting neither sex forms kin associations. I found that most clutches had a single father and mother, but there was evidence of multiple paternity and intraspecific nest parasitism. Annually, most males fathered single broods, the proportion of males in Alberta fathering offspring during their lifetime averaged 45.9%, and reproductive variance was lower than expected if only a small proportion of males mated. For the historic analysis, I found high diversity during each time period with no decline through time. Genetic structure did not change and there was no evidence of a genetic bottleneck. Effective population size in Canada decreased with time and was estimated at 46.8 -- 93.6 individuals for the most contemporary time period. Together, my findings suggest that more birds are breeding than expected for a lekking species and Sage-Grouse in Canada are part of a genetically diverse population that is maintaining genetic connectivity through dispersal.