Domestication affects sex-biased gene expression evolution in the duck

Abstract

Genes with sex-biased expression are thought to underlie sexually dimorphic phenotypes and are therefore subject to different selection pressures in males and females. Many authors have proposed that sexual conflict leads to the evolution of sex-biased expression, which allows males and females to reach separate phenotypic and fitness optima. The selection pressures associated with domestication may cause changes in population architectures and mating systems, which in turn can alter their direction and strength. We compared sex-biased expression and genetic signatures in wild and domestic ducks ( Anas platyrhynchos ), and observed changes of sexual selection and identified the genomic divergence affected by selection forces. The extent of sex-biased expression in both sexes is positively correlated with the level of both d N /d S and nucleotide diversity. This observed changing pattern may mainly be owing to relaxed genetic constraints. We also demonstrate a clear link between domestication and sex-biased evolutionary rate in a comparative framework. Decreased polymorphism and evolutionary rate in domesticated populations generally matched life-history phenotypes known to experience artificial selection. Taken together, our work suggests the important implications of domestication in sex-biased evolution and the roles of artificial selection and sexual selection for shaping the diversity and evolutionary rate of the genome.

Evolution and expression patterns of the neo-sex chromosomes of the crested ibis

“…In mammals, the Y chromosome is characterized by the presence of male reproductive genes and may constitute a battleground for sexual selection 11,13 . However, unlike mammalian Y chromosomes 76 , previous research has suggested that the W chromosome from birds is not associated with female-biased gene expression 13,14,53,63,86,87 . Surprisingly, in contrast to previous results from core land birds, the neo-W chromosome of the crested ibis appears to show female-biased expressions or ovarian-specific expressions from both ancient and new evolutionary strata.…”