Passer sparrows (completed)
On the evolutionary genomics and behavioural ecology of homoploid hybrid speciation in Passer sparrows
About the project
The Italian sparrow is a stabilized homoploid hybrid species that has originated from hybridization events between house sparrows and Spanish sparrows in the past. Using pyrosequencing of cDNA on the 454-platform at CEES we will characterize and compare the transcriptomes of the hybrid species and its parental species to investigate the genomic changes that has occurred in association with this rare speciation event. The sequencing will also provide the necessary SNP-markers for the project. We will genotype a selected sample of these SNP markers on a large number of birds to reconstruct the phylogeographic history of the species complex and to investigate pattern of introgression across transects of hybrid zones between the species. We will include markers from genes showing signals of being affected by selection in either species along with presumably neutrally evolving markers to investigate possible differential introgression and selection against hybrid genotypes in the contact zones. Potentially favorable hybrid genotypes will also be looked for. The second part of the project is concerned with investigations of barriers against gene flow among sparrows bred in captivity. We will maintain six mixed-species populations in the lab and allow them to mate and breed. All adults and nestlings will be genotyped to check paternity. Pattern of assortative pair formation and fertilization will be investigated, as well as potential developmental problems (including reduced fertility) of hybrid descendants. Genotyping of captive birds with known pedigree (using a denser, genome-wide SNP-marker set) will be used to investigate the genetic architecture of traits of interest, that is, traits associated with reproductive isolation. Finally, we will investigate whether species recognition is genetically inherited or caused by sexual imprinting on parental phenotype by cross-fostering experiments of nestlings in the lab-reared populations.
This project funded by The Research Council of Norway.
Start: 1.4.2011. End: 31.03.2014.