| Abstract: | In Europe, the Quaternary is characterized by climatic fluctuations known to have led tomany cycles of contraction and expansion of species geographical ranges. In addition,during the Holocene, historical changes in human occupation such as colonization orabandonment of traditional land uses can also affect habitats. These climatically oranthropically induced geographic range changes are expected to produce considerableeffective population size change, measurable in terms of genetic diversity andorganization. The rock ptarmigan (Lagopus muta) is a small-bodied grouseoccurring throughout Northern hemispheric arctic and alpine tundra. This species is notconsidered threatened at a continental scale, but the populations in the Pyrenees are ofconcern because of their small population size, geographical isolation and low geneticdiversity. Here, we used 11 microsatellites to investigate genetic variations anddifferentiations and infer the overall demographic history of Pyrenean rock ptarmiganpopulations. The low genetic variability found in these populations has been previouslythought to be the result of a bottleneck that occurred following the last glacial maximum(i.e., 10 000 years ago) or more recently (i.e., during the last 200 years). Ourresults clearly indicate a major bottleneck affecting the populations in the last tenth ofthe Holocene. We discuss how this decline can be explained by a combination of unfavorableand successive events that increased the degree of habitat fragmentation. |
