Evidence of admixture between differentiated genetic pools at a regional scale in an invasive carnivore

Abstract

Invasive species represent a major threat to biodiversity, and the understanding of their population genetics is one of the most important goals in conservation biology. Recently, it has been proposed that methods using molecular tools could help define efficient eradication strategies and should be a preliminary step in the management process. The American mink was introduced in Europe for fur farming purposes in the 1920s, and, due to escapees, several feral populations have been mentioned in the last decades. In France, feral mink have been observed since the 1970s, and the largest population, located in Brittany, is considered to be still expanding. We investigated the genetic variability and population structure of 149 feral mink and 21 farmed mink from this area using six microsatellite loci. Our results showed three genetically distinct population units at the regional scale. A pattern of isolation by distance was observed for the whole sample. In our case we explain this pattern by recent admixture of the three genetic units. Our findings suggest that populations have recently met and started to homogenise.

Divergence-with-Gene-Flow—What Humans and Other Mammals Got up to

“…The American mink, alternatively called Neovison vison or Mustela vison (we will refer to this taxon as N. vison), has been utilized as a source of fur from both wild-caught and captive-reared animals (Kidd et al 2009;Bifolchi et al 2010). The utilization of so-called farmed animals in fur production in North America and Europe has resulted in feral populations formed from escaped individuals.…”

“…In Europe, where escaped populations of the non-native N. vison can be viewed as an invasive species, a different scenario has been detected. Specifically, Bifolchi et al (2010) reported that the genetic makeup of feral populations of American mink in Brittany reflected hybridization and introgression among genetically divergent lineages. This pattern of admixture was likely a reflection of both inbreeding in the farmed populations leading to divergent subpopulations that then escaped and also the history of introductions of captive animals from North America that derived from three separate N. vison subspecies (Bifolchi et al 2010).…”

“…Specifically, Bifolchi et al (2010) reported that the genetic makeup of feral populations of American mink in Brittany reflected hybridization and introgression among genetically divergent lineages. This pattern of admixture was likely a reflection of both inbreeding in the farmed populations leading to divergent subpopulations that then escaped and also the history of introductions of captive animals from North America that derived from three separate N. vison subspecies (Bifolchi et al 2010). Thus, as with the North American native x wild hybrids, the admixed populations in France reflect novel genotypes due to introgressive hybridization between divergent mammalian lineages.…”

Reticulate Evolution

“…In North America, the escapee populations have introgressed with natural populations of N. vison, leading to concerns over the conservation of the native populations. Specifically, Bifolchi et al (2010) reported that the genetic makeup of feral populations of American mink in Brittany reflected hybridization and introgression among genetically divergent lineages. Thus, hybridization between the escaped and wild populations could lead to the genetic extirpation of the native gene pool, or alternatively, the production of novel lineages that form the basis of further evolutionary innovation (Arnold 1997(Arnold , 2006Seehausen 2004).…”

“…For example, in two populations in Ontario (Canada) consisting of escaped, wild, and hybrid mink, Kidd et al (2009) detected only 36 % wild individuals, with the remainder being hybrid (10 and 46 %) or escaped genotypes. This pattern of admixture was likely a reflection of both inbreeding in the farmed populations leading to divergent subpopulations that then escaped and also the history of introductions of captive animals from North America that derived from three separate N. vison subspecies (Bifolchi et al 2010). In Europe, where escaped populations of the non-native N. vison can be viewed as an invasive species, a different scenario has been detected.…”