The thornback ray Raja clavata is widely distributed in Mediterranean, Black Sea and the Atlantic coasts of Europe and Africa. The species has high commercial value in European waters; it is locally commercially important in Mediterranean where it is part of the by-catch associated with demersal fisheries. Because the recent decreases in abundance and distribution, the species was assessed in the IUCN Red List as Near Threatened. This study deals with the genetic diversity and the connectivity between Mediterranean and Atlantic samples in order to acquire useful information for management and conservation purposes. A total of 235 individuals were collected from eight sampling areas of Western, Central and Eastern Mediterranean and from Northeastern Atlantic and they were analyzed at nine polymorphic microsatellite loci. Low levels of genetic diversity were found (uHe=0.477), with the highest values recorded in the North Sea (0.525) while the lowest in the Tyrrhenian Sea (0.432). A fable but significant overall genetic differentiation was detected among all the investigated populations (Fst=0.039, P<0.05). Nevertheless, Mantel test allowed the rejection of the hypothesis of isolation by distance. No genetic differences were found grouping samples according to the two major geographical areas (Mediterranean vs Atlantic, AMOVA: FCT=0.007, NS). However, a significant differentiation emerged within the Mediterranean among Western /Central/Eastern samples (AMOVA: FCT= 0.047, P<0.05) . In particular, Cyprus was found to be highly divergent from all the other samples, showing the highest pairwise Fst and Dest values. According to the Bottleneck results, all the investigated populations showed a substantial demographic stability. These data provide a significant contribution for the planning of an effective management model, ensuring sustainability of resource
Detecting genetic differentiation and connectivity among Raja clavata populations within the Mediterranean Sea
CARIANI, ALESSIA;TINTI, FAUSTO;
2014
Abstract
The thornback ray Raja clavata is widely distributed in Mediterranean, Black Sea and the Atlantic coasts of Europe and Africa. The species has high commercial value in European waters; it is locally commercially important in Mediterranean where it is part of the by-catch associated with demersal fisheries. Because the recent decreases in abundance and distribution, the species was assessed in the IUCN Red List as Near Threatened. This study deals with the genetic diversity and the connectivity between Mediterranean and Atlantic samples in order to acquire useful information for management and conservation purposes. A total of 235 individuals were collected from eight sampling areas of Western, Central and Eastern Mediterranean and from Northeastern Atlantic and they were analyzed at nine polymorphic microsatellite loci. Low levels of genetic diversity were found (uHe=0.477), with the highest values recorded in the North Sea (0.525) while the lowest in the Tyrrhenian Sea (0.432). A fable but significant overall genetic differentiation was detected among all the investigated populations (Fst=0.039, P<0.05). Nevertheless, Mantel test allowed the rejection of the hypothesis of isolation by distance. No genetic differences were found grouping samples according to the two major geographical areas (Mediterranean vs Atlantic, AMOVA: FCT=0.007, NS). However, a significant differentiation emerged within the Mediterranean among Western /Central/Eastern samples (AMOVA: FCT= 0.047, P<0.05) . In particular, Cyprus was found to be highly divergent from all the other samples, showing the highest pairwise Fst and Dest values. According to the Bottleneck results, all the investigated populations showed a substantial demographic stability. These data provide a significant contribution for the planning of an effective management model, ensuring sustainability of resourceI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
