Unexpected genetic integrity boosts hope for the conservation of the red-legged partridge (Alectoris rufa, Galliformes) in Italy

Abstract

The red-legged partridge (Alectoris rufa) is a medium-sized galliform endemic to southwestern Europe. In the easternmost part of the species’ range, the population inhabiting Elba Island (Tuscan Archipelago National Park, Italy) is of undisputed conservation value. While we found nuclear and maternal DNA introgression with the exotic chukar partridge (A. chukar) in previous studies based on microsatellite DNA (n = 25) and two mitochondrial markers (n = 103), respectively, we disclosed a limited or null admixture in a few Elban partridges (n = 4) in a recent genomic investigation relying on 168,675 Single Nucleotide Polymorphisms (SNPs). We herein carried out an extended microsatellite DNA survey including additional 65 samples (total, 90) and six loci (total, 11) to determine both spatial structure and genetic integrity of local A. rufa. A sharp divergence between the subpopulations inhabiting the two sides of the island was disclosed, and the microsatellites indicated that all Elban partridges were not admixed with the chukar, thus fully reflecting the picture inferred using SNPs. We hypothesized that the spreading of chukar genes was constrained by negative selection, with the persistence of only the maternal lineage being indicative of thermal adaptation. The two subpopulations should be treated as distinct Management Units, and an envisaged plan to secure a stock onto nearby Pianosa Island could not only warrant endurance of the Elban population but also establish a source of valuable founders for the ex-situ management of the species in Italy. Our study exemplifies how a suitable samples/loci combination is the key to solve wildlife issues dealing with introgression.