Genetic diversity and population structure of the Eurosian otte (Lutra lutra) in France

During the last century, the Eurasian otter (Lutra lutra) suffered a dramatic decline in Europe. In France, the same pattern of sharp decline was observed with local extinctions in many regions. Before the recolonisation process, two main populations still remained along the Atlantic coast and in the Massif Central. To investigate the impact of this decline on the genetic diversity and structure of the French otter population, tissue samples of 144 otter carcasses from road kills that were found during 1992–2011 along the Atlantic coast and in the Massif Central were used. They were analysed using 10 microsatellites loci. Observed (H o = 0.64) and expected heterozygosity (H e = 0.62) were moderate, but consistent with results found in other European populations. The bottleneck test showed an excess of heterozygotes, providing evidence of a recent decline. There was evidence for weak but significant allelic frequencies divergence between otters from the Atlantic coast and those from the Massif Central (F st = 0.040, p < 0.05), probably resulting from their isolation prior to the recolonisation process. As the French otter population has been expanding for several years, genetic intermixing is now occurring. Although this expansion has not yet genetically homogenised all populations, this is may be a matter a time.