Abstract
The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides) in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species’ dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large ‘central’ population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.
Highlights
Non-native species pose a great threat to the integrity of natural systems and are of evolutionary interest because genetic processes may play a role in their establishment and spread
The extent of gene flow during the range expansion of an invader does, influence the amount of genetic diversity retained in newly founded populations [4]
The three genetic populations identified by both algorithms corresponded in essence to Finland, Denmark and one larger cluster encompassing all the remaining pre-defined populations (Fig 2)
Summary
Non-native species pose a great threat to the integrity of natural systems and are of evolutionary interest because genetic processes may play a role in their establishment and spread. The extent of gene flow during the range expansion of an invader does, influence the amount of genetic diversity retained in newly founded populations [4]. Genetic diversity at the expanding range front may be declining as a result of recurrent bottlenecks and founder effects [5], which, in the absence of admixture, can lead to significant gradients in allele frequencies among populations [6,7]. A large amount of migration and gene flow between neighbouring populations will preserve the genetic diversity of the source population [4]. Given the outcomes of these alternative scenarios, genetic analyses offer a promising tool to understand the colonisation history of invading species
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