Abstracts (first author)
Genetic and genomic insights into a colour polymorphism of the Gouldian finch (Erythrura gouldiae)
The Red locus of the Gouldian finch Erythrura gouldiae is a pigmentation switch that determines black (melanin) and red (carotenoid) morphs. This locus offers a unique opportunity to investigate the genetic basis and evolutionary history of a sympatric polymorphism for colour that has also been found to be associated with multiple physiological and behavioural differences. We used classical linkage mapping combined with RAD (Restriction site Associated DNA) sequencing and association analysis to localize the locus to a small (65-kb) genomic region. The pattern of nucleotide diversity at the Red locus is characterized as a genomic island that shows significant differentiation and divergence between the black and red haplotypes. Evolutionary theory suggests two distinct hypotheses to explain this pattern. First, sequence divergence may have accumulated within the species due to reduced gene flow between morphs, supported by the observed high degree of pre- and post-zygotic incompatibility, or due to a genomic rearrangement. Second, the sequences may have diverged in isolated lineages, prior to population merger or introgression. We examined the two alternative possibilities by using genetic and genomic tools and assess the evidence for balancing selection.