| Summary: | Tese de mestrado, Biologia da Conservação, 2022, Universidade de Lisboa, Faculdade de Ciências Atlantic salmon (Salmo salar L.) is an anadromous species with homing behaviour. Generally, individuals from this species are born in freshwater systems, migrate to feeding grounds in North Atlantic and return to their birthplace to reproduce. This reproductive isolation potentiates local adaptation. In recent years, Atlantic salmon populations in Europe have experienced great declines and are now classified as Vulnerable (VU). In Portugal, very little is known about this species, but this species is classified as Critically Endangered (CR), the highest threatened status. In this work, 14 microsatellite loci are used to assess population structure, migratory patterns and genetic diversity of 28 already identified and analysed populations (Gilbey et al., 2018), plus two additional populations, one from Galicia, Spain (Lerez River) and the other from Portuguese Minho basin (Mouro River). This is the first work to analyse Portuguese Atlantic salmon population’s genetics. The goal of the present study was to assess if the Portuguese populations were genetically distinguishable from other European populations. This work described a new Iberian genetic cluster, which is pointed out by several analysis (namely, STRUCTURE, PCoA and POPTREE2). This new group has a similar degree of differentiation from the Main European clusters as the Icelandic cluster that was described in previous works. Another important discovery described was the high relatedness among populations from Portugal and Galicia, when compared with the Asturian population, all located in the Iberian Peninsula. The genetic diversity analysis showed that the genetic uniqueness of each population is decreasing if compared to other works. The estimates of population effective size (Ne) indicate low Ne in most of the populations. It concludes that future genetic approaches to this species must consider this new Iberian cluster. On the other side, more studies must ...
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