Abstract
BackgroundMany western European carnivore populations became almost or completely eradicated during the last ~200 years, but are now recovering. Extirpation of wolves started in Finland in the 19th century, and for more than 150 years the population size of wolves has remained small. To investigate historical patterns of genetic variation, we extracted DNA from 114 wolf samples collected in zoological museums over the last ~150 years. Fifteen microsatellite loci were used to look at genotypic variation in this historical sample. Additionally, we amplified a 430 bp sequence of mtDNA control region from the same samples. Contemporary wolf samples (N = 298) obtained after the population recovery in the mid-1990s, were used as a reference.ResultsOur analyses of mtDNA revealed reduced variation in the mtDNA control region through the loss of historical haplotypes observed prior to wolf declines. Heterozygosity at autosomal microsatellite loci did not decrease significantly. However, almost 20% of microsatellite alleles were unique to wolves collected before the 1960s. The genetic composition of the population changed gradually with the largest changes occurring prior to 1920. Half of the oldest historical samples formed a distinguishable genetic cluster not detected in the modern-day Finnish or Russian samples, and might therefore represent northern genetic variation lost from today’s gene pool. Point estimates of Ne were small (13.2 and 20.5) suggesting population fragmentation. Evidence of a genetic population bottleneck was also detected.ConclusionsOur genetic analyses confirm changes in the genetic composition of the Finnish wolf population through time, despite the geographic interconnectivity to a much larger population in Russia. Our results emphasize the need for restoration of the historical connectivity between the present wolf populations to secure long-term viability. This might be challenging, however, because the management policies between Western and Eastern Europe often differ greatly. Additionally, wolf conservation is still a rather controversial issue, and anthropogenic pressure towards wolves remains strong.
Highlights
Many western European carnivore populations became almost or completely eradicated during the last ~200 years, but are recovering
Even though it is likely that the Finnish wolf population underwent heavy local population declines in the 1920s and 1970s [12,16,17], our results indicate that the largest genetic changes are probably of older origin, and connected to the assumed abrupt population decline in the turn of the 19th and 20th centuries (Figure 1)
The Finnish wolf population has been demographically dependent on the neighbouring Russian wolf population for a long time
Summary
Many western European carnivore populations became almost or completely eradicated during the last ~200 years, but are recovering. Extirpation of wolves started in Finland in the 19th century, and for more than 150 years the population size of wolves has remained small. By the end of the 19th century, most of the Western European wolf populations were extirpated [9], or at least driven into isolated and fragmented habitat patches [7,10]. Genetic studies reveal recent fragmentation in the Eastern European wolf population resulting in relatively small (local) effective population sizes [10], significant genetic differentiation and low migration rates between regions [13,15]. The historical effects of fragmentation on reductions in population size and loss of genetic variation is currently unknown
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