| Summary: | Hybridisation can lead to genomic admixture between populations that were previously isolated. Increased anthropogenic transportation of species, along with habitat and climate change mediating contact of populations, has caused multiple cases of ‘extinction by hybridisation’. This is when introgression leads to the loss of a population or species as a form distinct from its hybridising relative. In this thesis, I use the undomesticated Rock Dove (Columba livia) and its widespread conspecific, the feral pigeon, to explore the process of genomic replacement that characterises ‘extinction by hybridisation’. Specifically: (i) I review the scientific and conservation importance of the wild forms of domestic animals, and discuss the threats they face following gene flow from their feral conspecifics; (ii) I introduce the Rock Dove, outlining its status in the British Isles, and highlight its currently poor conservation prospects given ongoing interbreeding with the superabundant feral pigeon; (iii) I carry out the first population genomic study of the wild Rock Dove, identifying both hybrid populations as well as those exhibiting negligible signs of feral pigeon introgression; (iv) I show that interbreeding correlates with increased genomic diversity in hybridising populations, and discuss the potential benefits of gene flow between the lineages; (v) I show that plumage patterns can be used, at a population level, to make inferences about the extent of hybridisation in different Rock Dove colonies, and (vi) I examine variation in the prevalence and diversity of the disease- causing parasite <i>Trichomonas</i> among wild, feral and hybrid populations of <i>Columba livia</i>, and suggest that disease transmission may influence patterns of gene flow. Overall, this body of work extends our understanding of the process of extinction by hybridisation, specifically relating to scattered, relictual undomesticated populations which are in contact with conspecific feral domestic populations. It also provides a greater understanding of the wild Rock Dove’s genomic status and basic biology. Characterisation of the wild Rock Dove will extend the utility of the domestic pigeon as a major model organism in urban evolution, developmental genetics, and behavioural science, by allowing for a greater understanding of trait evolution and natural behaviour in a species which has been predominantly studied in a laboratory setting.
|
|---|