Abstracts (first author)
TSHR -a possible domestication genePDF
Domestication, the process where wild animals adapt to captivity, offers an excellent model to study evolution. Strong selection for traits of human interest causes genetic adaptations and a rapid change in morphology, physiology and behaviour. The Red Jungle Fowl (Gallus gallus) is the wild ancestor of domesticated chickens. Resequencing has revealed a selective sweep in domestic chickens over the thyroid stimulating hormone receptor gene (TSHR). A missense mutation in TSHR causing a glycine to arginine change is the most obvious candidate causal mutation for the sweep. Thyroid hormones are important in development and the thyroid system is suggested to correlate with stress response and hence behaviour in animals. Fast development and altered behavioural responses are traits shared by all domesticated animals. Therefore, we hypothesize that a mutation in the TSHR gene has been of selective advantage during the domestication of the chicken. To study this, we used intercrosses between Red Junglefowl and domesticated White Leghorns. We included 28 birds homozygous for the TSHR mutation, 34 homozygous for the wild-type allele and 62 heterozygous birds, and subjected them to a broad phenotyping. Incubation time was recorded in order to measure development and behavioral tests for social, aggressive and fear behaviors were conducted. Individuals homozygous for the TSHR mutation had longer incubation time (21,7 ± 1,3 vs. 18,0±1,2 and 18,2±1,0 h from first hatch p<0,05), showed less aggression in a social dominance test (8,6±4,8 vs. 26,9±4,8 and 18,6±4,8 number of observations p<0,05) and less fear in a fear of human test (2,2±2,5 vs. 14,9±2,3 and 16,3±1,9 % of observations p<0,05) in comparison to the other genotypes. The results are in line with previous studies comparing pure-bred domestic White Leghorns with pure-bred Red Jungle Fowl. This indicates that a mutation in the TSHR gene could have been of selective advantage during the domestication of the chicken.