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Identifying highly diagnostic molecular markers from domestication genes to efficiently detect hybrids between wolf/dog and wild/domestic cat

Hybridization between wolves (Canis lupus) and dogs (Canis familiaris), as well as between wild cats (Felis silvestris silvestris) and domestic cats (Felis s. catus), is a growing conservation problem worldwide. Essentially, this is a consequence of human activities that in the last decades have caused drastic habitat modifications, extinction and confinement of predator populations and facilitation of the spread of feral dogs and cats. Recent studies have shown, for example, the occurrence of F1 wolf/dog hybrids in Scandinavian and North American populations and an apparently widespread admixture between wild and domestic cats in various regions of the world. When, a few years ago, molecular markers became widely used and the field of conservation genetics gained maturity, it was immediately clear that they had the potencial to solve the problem of hybrid identification. While the sole use of the mitochondrial DNA (mtDNA) molecule was limited, due to its specific inheritance mode and single locus nature, the hope was that hyper-variable microsatellites would offer a definitive diagnostic tool. However, it is now clear that due to the very high similarity of the genomes of the wild species and their domestic relatives, only by using microsatellite loci in numbers much higher than those currently used in conservation genetic programs could hybrids be efficiently identified in most cases. Recent simulation data clearly suggest that the magnitude of the problem of hybridization in wolves/dogs and wild cats/domestic cats may be much higher than previously thought. In addition, they also indicate that a new generation of more powerful markers is required if we want to efficiently address this problem. 

Taking these difficulties into consideration, it is likely that the recent availability of the dog genome together with the relevant advances in the cat genome, are offering a new avenue to solve the problem of hybrid detection. In fact, recent studies suggest that a significant part of a genome is sculpted by strong artificial selection during the early steps of domestication, or later, during breed improvement. Consequently, it is to be expected that these genomic regions should differ significantly between wild species and the corresponding domestic counterparts. While relevant comparative studies of this type are still lacking in mammals, recent studies focusing on maize suggested that two to four per cent of their genes experienced artificial selection, indicating a rough estimate of the fraction of the genome of a domesticate that was shaped by artificial selection. Concerning the wolf/dog and wild cat/domestic cat problems addressed in this project, we suggest that a candidate gene approach is the most appropriate course of action. In fact, these wild/domestic pairs strongly differ in various body and life traits that include coat, morphology, reproduction and behaviour. In the last few years, an increasing flow of papers is helping to identify candidate genes that may be involved in the above-mentioned characteristics. Furthermore, these characteristics and underlying genes have been studied in livestock (cattle, sheep) and studies suggest that the same genes are often involved on similar adaptations in different species. This means that genes or QTL in livestock associated with domestication traits are strong candidate genes for domestication traits in dogs and cats. If these candidate genes, or the genomic regions where they are located, were indeed affected by strong selective forces during domestication and/or breed improvement, then it is very likely that these regions will provide highly informative molecular markers – both single nucleotide polymorphisms (SNPs) and microsatellites – to effectively distinguish hybrids between wild and domestic individuals. With this proposed project we expect to identify genes, or genomic regions, that were involved in domestication and breed improvement for both dogs and cats, and select a set of highly informative molecular markers for the distinction of hybrids and the analysis of introgression in populations of Canis lupus and Felis silvestris. These markers should prove useful in a variety of conservation programs for the targeted species. On the other hand, we will also contribute to improve our understanding on how selection has shaped molecular diversity in both dogs and domestic cats, adding invaluable insights into the history of domestication of the two man’s best friends.

Principal Investigator
Raquel Godinho

Raquel Godinho

Position: Principal Researcher
Other members
Joaquim Pedro Santos Mercês Ferreira, Ana Elisabete Godinho Pires, Maria Margarida Mello Santos Reis G Fonseca, Carlos Alberto Rodrigues Fernandes, Francisco José Petrucci Guterres da Fonseca, Isabel Maria Amorim do Rosário, Rita Isabel Ribeiro Miranda De Oliveira
Proponent Institution
Instituto de Ciências e Tecnologias Agrárias e Agro-Alimentares - Porto (ICETA-Porto/UP)
Funded by
0000 (Duration: 2011 years)
Participant Institutions
Centro de Investigação em Biodiversidade de Recursos Genéticos (CIBIO/ICETA-Porto/UP), Fundação da Faculdade de Ciências da Universidade de Lisboa (FFC/FC/UL)
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