Genetic Variability of Alnus cordata (Loisel.) Duby Populations and Introgressive Hybridization with A. glutinosa (L.) Gaertn. in Southern Italy: Implication for Conservation and Management of Genetic Resources

Alnus cordata (Loisel.) Duby (Neapolitan alder) is an endemic tree species with a restricteddistribution range, limited to Corsica and southern Italy. The economic value of its wood, its rapidgrowth, the tolerance to drought stress and the nitrogen fixation capacity make A. cordata an excellentcandidate for breeding, as well as for conservation and management of genetic resources. Inthis context, we evaluated the genetic variability of southern Italy populations and verified the hybridizationcapacity with the simpatric species A. glutinosa (L.) Gaertn. Eight pure A. cordata populations,two pure A. glutinosa populations and six mixed A. cordata/A. glutinosa populations locatedin southern Italy were analyzed using seven microsatellite markers. A low genetic diversity withinand among populations was observed, but no inbreeding effects were evident. A variable frequencyof F2 interspecific hybrids was observed in most of the mixed populations and few backcross individualswere scored. These results suggest a limited capacity of hybrid individuals to cross backwith the parent species, reducing the risk of genetic pollution of A. cordata. This work providesmeaningful knowledge for the conservation and management of the endemic species A. cordata,which represents a valuable source of biodiversity to be conserved.