Introgression of chukar genes into a reintroduced red‐legged partridge (Alectoris rufa) population in central Italy

Abstract

Insight regarding the genetic origin and composition of the studied population of the red-legged partridge (Alectoris rufa) is likely to provide general and critical information for the appropriate management and possible conservation of the species. The reintroduced population of red-legged partridges living in Pianosa Island (National Park Tuscany Archipelago) has proven to be sustainable: captive-bred individuals, morphologically assigned to the taxon A. rufa, were released to the island approximately 20 years ago, establishing an apparently well-adapted population. We have investigated this population by means of 10 microsatellite loci in order to shed light on its genetic structure. Considering that A. rufa is known to crossbreed with A. chukar, the Pianosa Island population was compared at the molecular level with a red-legged partridge breeding stock (Aulla, MS) as well as with a population of pure A. chukar. Our results indicate that the red-legged partridge population from Pianosa, morphologically identified as A. rufa, is actually partly introgressed with A. chukar, questioning its genetic purity and the possible use of this population as a starting stock for future reintroductions elsewhere.

Mitochondrial DNA and microsatellite markers evidence a different pattern of hybridization in red-legged partridge (Alectoris rufa) populations from NW Italy

“…Despite their endangered status, the genetic make-up of residual red-legged partridge populations in Italy remains partially unknown. Actually, genetic investigation of A. rufa has focused on reintroduced/restocked populations in the islands of the Tuscan Archipelago, and on captive partridges from three Tuscan farms (Baratti et al 2004;Barbanera et al 2005Barbanera et al , 2009Guerrini and Barbanera 2009). However, genetic data on wild mainland populations are still needed.…”

“…Uncertainty in the assignment of admixed individuals can be reduced by defining strict threshold values of the individual proportion of membership (qt) and their 90 % credible intervals (90 %CI), which are expectedly larger in admixed individuals (Randi 2008). In order to improve the accuracy of hybrid detection, we adopted a more stringent qt threshold value (>95 %) with respect to other studies (Randi et al 2003;Baratti et al 2004;Barilani et al 2007a, b) and a 90 % CI within the range 0.9-1.0. The Bayesian clustering procedure identified seven putative introgressed individuals (6.5 % of the total sample) in comparison to 34 cases of maternal introgression (19.3 % of the total sample) directly found by discordant mtDNA and morphological traits.…”

“…Investigations on hybrid zones suggested that admixed individuals can show higher fitness in novel or previously underexploited habitats (Burke and Arnold 2001;Seehausen 2004). Baratti et al (2004) evoked hybrid superiority to partially explain the successful adaptation of a redlegged partridge population affected by chukar introgression in a xeric environment of Pianosa Island (Tuscany), which is not particularly suitable for .4. rufa. Other factors, such as reduced predator pressure, poaching control, and a strict ban on hunting have probably favored the rapid demographic expansion of admixed partridges along the river basin investigated in our study.…”

Threats from introduced birds to native birds

“…Correlative studies using molecular genotyping indicated that hybridisation with the Chukar is widespread across the natural range of the Red-legged Partridge (Baratti et al 2005;Barbanera et al 2005;Barilani et al 2007;Tejedor et al 2007;Blanco-Aguiar et al 2008) and present in the native distribution of the Rock Partridge, leading to introgressive hybridisation (Barilani et al 2007). Hybridisation between Red-legged and Rock Partridges occurs naturally in hybrid zones in the southern French Alps (Barilani et al 2007) but in Spain, the Rock Partridge has been deliberately introduced to breed with the Red-legged Partridge for hunting, which may be threatening the genetic integrity of native Red-legged Partridge populations (Arruga et al 1996;Negro et al 2001).…”

“…Hybridisation between Red-legged and Rock Partridges occurs naturally in hybrid zones in the southern French Alps (Barilani et al 2007) but in Spain, the Rock Partridge has been deliberately introduced to breed with the Red-legged Partridge for hunting, which may be threatening the genetic integrity of native Red-legged Partridge populations (Arruga et al 1996;Negro et al 2001). Although there is some regulation of the stock that is released for hunting, hybridisation remains a potential threat, particularly hybridisation with the Chukar (Barbanera et al 2005;Baratti et al 2005;Barilani et al 2007).…”