Abstracts (first author)
Effects of a mutation in the adrenergic receptor gene ADRA2C, selected during chicken domestication, on gene expression, receptor density and behaviourPDF
During domestication, chickens have been selected for genotypes which confer selective advantages in conditions under human care and rearing, but little is known about the detailed genetic mechanisms involved. In a recent study of selective sweeps associated with domestication, resequencing of different chicken breeds reveled a number of strongly selected loci. One of those, containing the α-adrenergic receptor 2C (ADRA2C), was found to be selected in layer chickens. Furthermore, previous studies from our group show that the receptor is hyper-methylated in White Leghorn (WL) chickens compared to the Red Junglefowl (RJF) ancestor, suggesting the gene to be differently expressed. ADRA2C is a presynaptic autoreceptor modulating epinephrine and norepinephrine release within the central nervous system and secretion of epinephrine from the adrenals. A down-regulation is associated with increased catecholamine secretion. Hence, domestication on the receptor might have an impact on stress responses, memory formation and egg production. We used F9-birds from an intercross between domesticated WL and RJF, and selected parents which were heterozygous for the mutation in ADRA2C generating offspring with all genotypes represented. This allowed within-family comparisons of the effects of the mutation against a randomly recombined genome. We used an array of stress related behavioral tests and we measured differences in brain expression of the gene as well as receptor density. Briefly birds with the mutation tended to have impaired associative learning and recovered more quickly after exposed to an aerial predator model. We hypothesize that the domestication of chickens have selected birds with hypo-expressed levels of ADRA2C, generating an increased catecholamine release, and that this has caused modifications of the stress response.