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Tesi etd-03022014-011442

Thesis type
Tesi di dottorato di ricerca
Molecular evolution and conservation genetics of galliforms: the black francolin (Francolinus francolinus) and the red-legged partridge (Alectoris rufa)
Settore scientifico disciplinare
Corso di studi
tutor Dott. Barbanera, Filippo
Parole chiave
  • phylogeography
  • Francolinus
  • Alectoris
  • adaptive evolutionary conservation
Data inizio appello
Riassunto analitico
The importance of adaptive evolutionary conservation has been widely accepted. According to this concept, only a comprehensive evaluation pursued within both a temporal and a spatial perspective may enable to properly assess the potential conservation value of a given resource. This applies well to phylogeographic studies dealing with game birds subjected to intense and large-scale ex situ management. The present study attempted to gain useful genetic information to the adaptive conservation framework of two Palaearctic taxa deserving both evolutionary and conservation interest, namely the black francolin (Francolinus francolinus) and the red-legged partridge (Alectoris rufa) (Galliformes, Phasianidae). The former belongs to a group of five poorly known and secretive Asian species; the latter, claimed to be the most appreciated and economically relevant quarry species in southwestern Europe, suffers from extensive biotic homogenisation and hybridisation with the congeneric chukar partridge (A. chukar). Both taxa are threatened by hunting pressure and habitat loss over most of their distribution ranges.
The evolutionary history of F. francolinus was investigated in relation to its inter- and intraspecific genetic kinship through the amplification and sequencing of the entire Control Region gene (ca. 1170 bp), a set of microsatellite DNA markers providing complementary-to-mitochondrial DNA information. Moreover, the phylogeography of the species was thoroughly updated in light of a molecular approach by genotyping both modern (n = 205) and ancient (n = 76: first half of the XIXth century-1967) birds at a highly variable 185-bp long fragment of the Control Region. Remarkably, the sampling of F. francolinus museum specimens allowed to get around the problems represented by remoteness and political unrest peculiar to most of the species’ range as well as to elucidate the genetic affinity of some extinct populations once resident to the western Mediterranean. Special focus was given to Cyprus, this island representing the European stronghold of the entire genus. Specifically, the genetic make-up of birds (n = 59) hunted in the districts of Nicosia and Paphos was characterised. Captive francolins (n = 18) of unknown origin imported to a pet-centre in Nicosia were investigated as well. The phylogenetic reconstructions on the genus Francolinus concurrently supported the monophyly of each of the five species, whereas that of the entire group was suggested according to the proposal of a biogeographical model. The Indian sub-continent was evidenced as the ancestral area for the adaptive radiation of F. francolinus, thus producing weight for its westward adaptive radiation. Moreover, the molecular insight into the phylogeographic pattern of the species returned a poorly yet markedly sculptured genetic picture, the six morphological subspecies being arranged into three well-distinct mitochondrial DNA clusters. Nevertheless, the distribution of traditionally recognised subspecific taxa was revised as well, a more complex and intriguing scenario being disclosed along the Indus and Ganges river valleys in the Indian sub-continent. Molecular evidence for a likely human-mediated introduction of F. francolinus from Asia Minor to Cyprus was found, while the alleged introduction from Cyprus to Sicily was strongly suggested and the historically documented importation from the latter to Tuscany definitely proved. The mixed genetic origin of the extinct population inhabiting Sicily was disclosed as some of its representatives displayed an overt genetic affinity to conspecifics from southern Asia. The same affiliation emerged for an ancient black francolin from Spain, thus crediting the invoked introduction from Sicily into the latter. As far as Cyprus is concerned, the combined genetic systems disclosed the occurrence of genetically isolated wild district populations which should be treated as distinct Management Units. Moreover, the assignment of captive birds to alien Asian subspecies unveiled that genetic pollution may represent a further threat to the native F. francolinus population.
On the other hand, the first genetic survey of the introduced A. rufa resident to the UK was carried out to assess whether it could represent a useful genomic backup for the nominate subspecies. Specifically, an East Anglian population (n = 58) was genotyped at both 1092 bp of the mitochondrial Cytochrome-b gene and a panel of microsatellite loci, four species-specific A. rufa x A. chukar Random Amplified Polymorphic DNA markers providing further insights into their degree of genetic integrity. Furthermore, English A. rufa museum specimens (n = 13: 1824-1915) were characterised at a 229-bp long fragment of the Cytochrome-b to know if and to what extent the genetic diversity had been shaped over time by ex situ management. The picture inferred by mitochondrial DNA pointed to the tight genetic affinity of both historical and modern East Anglian birds with A. r. rufa from the easternmost part of the species’ range. Overall, an increase of diversity and decline of disparity over time within and among A. rufa populations emerged, respectively. Whereas no evidence of A. chukar mixed maternal ancestry was found in the ancient birds, introgression in modern ones was widespread, pointing to the irretrievable loss of the potentially high conservation value of this resource and precluding its possible employment for ex situ genetic conservation of A. r. rufa in its native range.