The Mediterranean Basin is a global biodiversity hotspot, bearing a high number of endemic species of freshwater fishes. The introduction of alien invasive species for fishing activities implementation has compromised, during years, the genetic integrity of Mediterranean trout (Salmo cettii, syn. Salmo macrostigma), which may be headed towards extinction, being also more vulnerable to climate change compared to allochthonous species. Given the considerable economic significance for fisheries and aquaculture of this species, a deep knowledge on trout populations structures and a proper method for spawners’ selection is necessary, to preserve native fauna and adopt a correct ecosystem approach in fisheries management. Here we present the results from the genetic characterization of 300 trout specimens, descriptive of the human-mediated hybridization process established between the native trout of Molise region (Central-Southern Italy) and the inter-fertile brown trout of Atlantic origin. Specimens were collected by electrofishing from different sampling stations of Biferno and Volturno rivers. Gene variability from LDH-C1* allozyme and mitochondrial 16S mtDNA data was evaluated by PCR-RFLP, analyzing on 2.5% agarose gel the fragments’ differences obtained after specific enzyme digestions. The use of two markers combination (nuclear and mitochondrial) allows to categorize the analyzed genotypes into six introgression classes (I-VI), establishing the level of hybridization, which goes from null level to maximum level. Obtained results show a different genetic introgression in the two rivers and a wide variability within each of them. More specifically, the Volturno exhibits a greater percentage of pure native trouts, while the Biferno has a higher percentage of Atlantic individuals, both pure and Atlantic fishes with a Mediterranean matrilineal line. Thus, the degree of heterozygous specimens in the Biferno is greater than Volturno. These information suggest that invasive Atlantic trout is seriously threatening the autochthonous populations, especially in Biferno river, further investigations are required, to know also the influence of morphological and environmental parameters on the introgression phenomenon of Mediterranean trout.
Ecology and biodiversity of Mediterranean trout in the main basins of Molise (Italy)
IAFFALDANO N.;DE ZIO E.;PALOMBO V.;TESTA B.;
2019-01-01
Abstract
The Mediterranean Basin is a global biodiversity hotspot, bearing a high number of endemic species of freshwater fishes. The introduction of alien invasive species for fishing activities implementation has compromised, during years, the genetic integrity of Mediterranean trout (Salmo cettii, syn. Salmo macrostigma), which may be headed towards extinction, being also more vulnerable to climate change compared to allochthonous species. Given the considerable economic significance for fisheries and aquaculture of this species, a deep knowledge on trout populations structures and a proper method for spawners’ selection is necessary, to preserve native fauna and adopt a correct ecosystem approach in fisheries management. Here we present the results from the genetic characterization of 300 trout specimens, descriptive of the human-mediated hybridization process established between the native trout of Molise region (Central-Southern Italy) and the inter-fertile brown trout of Atlantic origin. Specimens were collected by electrofishing from different sampling stations of Biferno and Volturno rivers. Gene variability from LDH-C1* allozyme and mitochondrial 16S mtDNA data was evaluated by PCR-RFLP, analyzing on 2.5% agarose gel the fragments’ differences obtained after specific enzyme digestions. The use of two markers combination (nuclear and mitochondrial) allows to categorize the analyzed genotypes into six introgression classes (I-VI), establishing the level of hybridization, which goes from null level to maximum level. Obtained results show a different genetic introgression in the two rivers and a wide variability within each of them. More specifically, the Volturno exhibits a greater percentage of pure native trouts, while the Biferno has a higher percentage of Atlantic individuals, both pure and Atlantic fishes with a Mediterranean matrilineal line. Thus, the degree of heterozygous specimens in the Biferno is greater than Volturno. These information suggest that invasive Atlantic trout is seriously threatening the autochthonous populations, especially in Biferno river, further investigations are required, to know also the influence of morphological and environmental parameters on the introgression phenomenon of Mediterranean trout.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
