View Program - 2022 Population, Evolutionary, and Quantitative Genetics Conference

My research aims to find the genetic bases of coloration in birds. I examined yellow, orange, and red carotenoid-based pigmentation, pivotal drivers of avian diversity, in order to understand how birds acquire color and how coloration differs between sexes. In order to establish an association between genotype and phenotype, I sequenced genomes of different canary breeds, identified candidate genes associated with difference in coloration and followed up with functional tests.
Firstly, I investigated how birds acquire carotenoid colouration. I examined mechanisms of carotenoid uptake, taking advantage of the white recessive canary breed, which carries an autosomal recessive mutation causing white plumage. Biochemical analysis revealed a genetic defect in carotenoid uptake, then genomic analyses showed that the white recessive allele is caused by a splice-donor site mutation in the scavenger receptor B1 gene (SCARB1). This mutation leads to a loss of function of the gene, which we demonstrated through functional assays. Taken together, SCARB1 is an essential mediator of the expression of carotenoid-based coloration in birds and suggests a potential link between visual displays and lipid metabolism.
Secondly, I analysed the molecular mechanisms of sexual dichromatism in birds (differences in coloration between males and females). Using a unique model of dichromatic hybrid canary in combination with genomic and transcriptomic analyses, I showed that dichromatism in mosaic canaries is controlled by a small autosomal region that alters the expression of the BCO2 gene in males and females, but specifically in the integument. To put the results in a broader evolutionary context, I applied transcriptomic analyses to a continuum of sexual dichromatism in finches that showed the importance of BCO2 for sexual dichromatism in other species. I demonstrated how large differences in ornamental coloration between sexes can evolve from simple molecular mechanisms controlled by genes of major effect and have important implications for theories of honest signaling and sexual selection.
My work is a significant contribution towards a better understanding of the evolution of avian coloration.

Genetic basis of carotenoid coloration in birds.