The nominal subspecies of rock partridge (Alectoris graeca graeca) is widely distributed in Greece, where populations are declining due to overhunting and habitat changes. Captive-reared chukars (A. chukar) have been massively released throughout the country, raising fear that introgressive hybridisation might have disrupted local adaptations leading to further population declines. In this study we used mtDNA control-region sequences and Bayesian admixture analyses of multilocus genotypes determined at eight microsatellite loci, to assess the extent of introgressive hybridisation in 319 wild rock partridges collected in Greece. A neighbour-joining tree split the mtDNA haplotypes into three strongly supported clades, corresponding to rock, red-legged (A. rufa) and chukar partridges. We did not detect any case of maternal introgression. In contrast, admixture analyses of microsatellite genotypes identified from four to 28 putative hybrids (according to different assignment criteria), corresponding to 1.2-8.8% of the samples, which were widespread throughout all the country. Power and limits of admixture analyses were assessed using simulated hybrid genotypes, which revealed that a small number of markers can detect all first and second generation hybrids (F 1 and F 2 ), and up to 90% of the first generation backrossess. Thus, the true proportion of recently introgressed rock partridges in Greece might be ca. 20%. These findings indicate that introgressive hybridisation is widespread, suggesting that released captive-bred partridges have reproduced and hybridised in nature polluting the gene pool of wild rock partridge populations in Greece.

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Interspecific hybrids raise a variety of developmental, reproductive, and evolutionary issues. In Sicily, geographically and chronologically distinct hybridizations between the highly differentiated Bacillus rossius and B. grandii have produced hybridogenetic strains and clonal parthenogenetic species. In northern Sicily, all-female populations of facultatively parthenogenetic B. rossius and bisexual B. grandii benazzii co-occur and we could test their current hybridization through electrophoretic marker analyses; control crosses with allopatric males were also carried out. Hybrid female progeny percentages ranged from 0 to 74 being fewer in egg batches laid by parthenogenetic mothers than in those of amphimictic females; no difference was noticed between sympatric and allopatric pairs. F1 hybrids of both sexes proved sterile; although some eggs started cleaving, no hemiclonal or clonal progeny hatched, only rare androgenetics being obtained. In currently produced hybrids a complete disruption of gametogenesis occurs, so that genetic constraints between parental taxa appear stronger now than in the past, most likely the result of ancestor evolution.

Interspecific hybrids raise a variety of developmental, reproductive, and evolutionary issues. In Sicily, geographically and chronologically distinct hybridizations between the highly differentiated Bacillus rossius and B. grandii have produced hybridogenetic strains and clonal parthenogenetic species. In northern Sicily, all-female populations of facultatively parthenogenetic B. rossius and bisexual B. grandii benazzii co-occur and we could test their current hybridization through electrophoretic marker analyses; control crosses with allopatric males were also carried out. Hybrid female progeny percentages ranged from 0 to 74 being fewer in egg batches laid by parthenogenetic mothers than in those of amphimictic females; no difference was noticed between sympatric and allopatric pairs. F1 hybrids of both sexes proved sterile; although some eggs started cleaving, no hemiclonal or clonal progeny hatched, only rare androgenetics being obtained. In currently produced hybrids a complete disruption of gametogenesis occurs, so that genetic constraints between parental taxa appear stronger now than in the past, most likely the result of ancestor evolution.