Threatened freshwater pearl mussel Margaritifera margaritifera L. in NW Spain: low and very structured genetic variation in southern peripheral populations assessed using microsatellite markers

Abstract

A genetic analysis of freshwater pearl mussel Margaritifera margaritifera populations from NW Spain, a peripheral area of its European distribution, was carried out using microsatellite markers. These populations were formerly reported as genetically differentiated on the basis of growth and longevity studies. Ten loci previously characterized in populations from central Europe were used to comparatively analyze the genetic variability at the southern edge of the species' range. Iberian pearl mussel populations showed very low genetic variability and significant high genetic differentiation. Half of the total genetic diversity observed appeared to be distributed between populations, which suggested a highly structured adaptive potential in pearl mussel at the southern peripheral distribution of the species. Population distinctiveness was evidenced by assignment tests, which revealed a high accuracy of individual assignments to their population of origin. All data suggested low effective population size and major effects of genetic drift on population genetic structure. In order to avoid further loss of genetic variation in biologically distinctive populations from NW Spain, prioritization of genetic resources of this species is required for conservation and management.

Variation in the COI gene of the freshwater pearl mussel Margaritifera margaritifera from River Vuokkijoki

“…Our analysis of a sample from the river Vuokkijoki is in concordance with studies of microsatellite markers that have indicated higher genetic diversity of M. margaritifera populations in the Northeast, than in populations from southern and central Europe (Geist et al, 2003Geist, Kuehn, 2005Bouza et al, 2007). For example, allelic richness of microsatellites, which is comparable to the measure of haplotype richness, was less than 2.0 in all Central European populations (Geist, Kuehn, 2005) and had an average of 2.1 in Iberian populations, (Bouza et al, 2007). Almost all Swedish populations had allelic richness of 2.7 or higher (2.7 to 3.6), and in populations from Finnish Lapland, allelic richness ranged between 4.0 and 4.7 (Geist, Kuehn, 2008;Geist et al, 2010).…”

“…Moreover, even though the sample was small, we found 10 COI haplotypes, three of which were unpublished and possibly unique to this population. Our analysis of a sample from the river Vuokkijoki is in concordance with studies of microsatellite markers that have indicated higher genetic diversity of M. margaritifera populations in the Northeast, than in populations from southern and central Europe (Geist et al, 2003Geist, Kuehn, 2005Bouza et al, 2007). For example, allelic richness of microsatellites, which is comparable to the measure of haplotype richness, was less than 2.0 in all Central European populations (Geist, Kuehn, 2005) and had an average of 2.1 in Iberian populations, (Bouza et al, 2007).…”

“…From 46 individuals, they found only two16S rRNA haplotypes and 10 COI haplotypes, which were resolved into two different mitochondrial lineages: a northern lineage, which stretches from Ireland to the Kola Peninsula, and a southern lineage, which stretches from Ireland to the Iberian Peninsula. Other studies using microsatellite markers (Geist et al, 2003Geist, Kuehn, 2005Bouza et al, 2007) have shown higher diversity in the northeastern populations than in the southern and central European populations. Microsatellite study by Karlsson et al (2014) revealed host-dependent genetic variation between M. margaritifera originating from salmon and trout rivers in Norway.…”

Strategies for the conservation of endangered freshwater pearl mussels (Margaritifera margaritifera L.): a synthesis of Conservation Genetics and Ecology

“…The same study revealed a close relation of specimens from both sides of the Atlantic. In contrast to allozyme and mitochondrial variability, analyses of microsatellites revealed high degrees of population structure and very different levels of genetic diversity among European populations (Geist et al, 2003;Geist & Kuehn, 2005;Bouza et al, 2007;Geist et al, 2009). Genetic variability as measured by allelic richness and heterozygosity levels appears to be the highest in the north-east of the species distribution range which can be explained by the species life history strategy and by the lesser extent of habitat destruction in these areas .…”

“…Genetic variability as measured by allelic richness and heterozygosity levels appears to be the highest in the north-east of the species distribution range which can be explained by the species life history strategy and by the lesser extent of habitat destruction in these areas . The strong genetic differentiation of pearl mussel populations, even within small geographical scales, may have been strongly enhanced by the effects of genetic drift, particularly in southern and central Europe (Geist & Kuehn, 2005;Bouza et al, 2007). The geographical distribution of genetic diversity in pearl mussel seems to be inversely related to that of its host fish, brown trout )-a phenomenon which can be explained by differences in the life history strategies and the ecological niches of the two species.…”