Genetic structure and diversity of the Iberian populations of the freshwater blenny Salaria fluviatilis (Asso, 1801) and its conservation implications

The freshwater blenny Salaria fluviatilis has a circum-Mediterranean distribution, but it is restricted to highly specific habitats and is particularly susceptible to human disturbances, leading to the decline of Iberian populations of the species, resulting in their classification as Vulnerable. The aim of this study is to evaluate the genetic diversity and structure of the Iberian populations of S. fluviatilis to facilitate the design of robust conservation programs for the species. Potential barriers among populations and recent bottlenecks were also identified. Eleven Iberian populations (N = 337) of S. fluviatilis were genotyped for twelve polymorphic microsatellites. Our results showed strong genetic structure among Iberian populations, clustering them into four groups: north-eastern Iberian group (Fluvia, Segre, Matarrana and Cabriel rivers and Albufera Lagoon), southern Iberian group (Verde, Guadaiza and Guadalmansa rivers), Atlantic group (Zujar River and Ruidera Lakes) and Banolas Lake (north-eastern Spain). Genetic diversity was higher in the north-eastern Iberian group (average observed heterozygosity H-o = 0.5 and number of alleles N-a = 4.9) compared with in the southern Iberian group (average H-o = 0.42 and N-a = 2.3), although the lowest observed heterozygosity was found in the Atlantic group (Ruidera Lakes, H-o = 0.324 +/- 0.106). The analyses also revealed a recent bottleneck in the southern Iberian group. Our results not only provide essential information for future conservation plans of the Iberian populations of S. fluviatilis but also for the maintenance of the species' genetic pool in general, for which the four clusters identified in this study should be considered.