An integrated genetic and morphological approach to clarify the conservation status of the threatened Italian endemic species Alburnus albidus (Cypriniformes: Cyprinidae)

The Italian bleak, Alburnus albidus, is a freshwater species endemic of southern Italy, that was recently classified as vulnerable in the IUCN Red List, due to the impact of introduced species. In this study, a combined genetic (mitochondrial cyt b and nuclear ITS1 DNA markers) and morphometric approach was applied to five populations from the whole range of A. albidus. Data were compared with those for the alborella A. arborella, an introduced species native to northern Italy. The results indicate a dramatic threat to A. albidus, as 39% of the specimens examined are the result of hybridization with other introduced cyprinids, mainly A. arborella. Hybrid individuals suggest bi-directional hybridization, but introgressed individuals exclusively show A. albidus nuclear genomes and A. arborella mitochondrial haplotypes. Morphological data discriminate the two parental Alburnus but not their hybrids or introgressed individuals. Genetic variability between the species is greater than the morphological variability. Ofanto River shows the most compromised situation suggesting the occurrence of multiple introductions, while Agri and Trigno populations are the most conserved, and deserve priority conservation actions. Given this, an update of the conservation status is recommended.