2024-03-28T22:29:54Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/2345662021-03-16T03:00:18Zcom_10261_77com_10261_8col_10261_330
00925njm 22002777a 4500
dc
Almodóvar, Ana
author
Leal, Sheila
author
Nicola, Graciela G.
author
Hórreo, José Luis
author
García-Vázquez, Eva
author
Elvira, Benigno
author
2020-03-12
Many Atlantic salmon Salmo salar populations in Europe are threatened by previous stocking with foreign hatchery strains. Temporal patterns of genetic characteristics of salmon from northern Spain, the southernmost European populations, were compared before and after species decline and heavy stocking with specimens from northern Europe. Eleven microsatellite loci were analysed in archival (scales from 1958-1960) and contemporary (2007-2008) samples from the River Sella. Temporal analyses revealed a similar heterozygosity between archival and contemporary samples, despite a drastic decrease in population abundance, while the contemporary sample showed a higher allelic richness due to the occurrence of foreign alleles. Considering only the alleles with at least 4% frequency in the archival sample, 2 alleles exclusive to the River Sella were absent in the contemporary sample, and 14 alleles showed a decrease of at least 4% frequency. Four alleles common in Scotland showed a high occurrence in the contemporary sample, so they are good candidates as markers of introgression of foreign genes. The heavy stocking with non-native Scottish broodstocks between 1970 and 1990 caused the introgression found in the contemporary sample when compared with the pristine population. An abrupt decrease was evident when the estimates of effective number of breeders were adjusted to take into account overlapping generations (Nb), effective population size (Ne) estimated from Nb, and number of breeders estimated using the sibship assignment method (Nb). The very low effective size values found in the contemporary sample, together with the detrimental synergy between genetic drift and high rates of introgression, represent a severe risk for the conservation of native salmon.
Endangered Species Research 41: 303-317 (2020)
http://hdl.handle.net/10261/234566
10.3354/ESR01029
http://dx.doi.org/10.13039/501100003329
http://dx.doi.org/10.13039/501100004837
Conservation genetics
Effective population size
Foreign stocking
Genetic variability
Introgression
Population genetics
Salmonidae
Long-term stocking practices threaten the original genetic diversity of the southernmost European populations of Atlantic salmon Salmo salar