An Analysis For Heritability Of Extra-pair Reproduction Of Ground Tits Pseudopodoces Humilis In Changdu,Tibet

Whether complex social traits have a genetic basis is an important question of evolutionary biology,and the answer to this question can help us to better understand the mechanism of social evolution.Such social traits are usuall y controlled by multiple genes,and their heritability can be estimated through pedigree-based quantitative genetics approaches.However,onl y a few social traits have been evaluated with respect to heritabilit y because of the difficult y to obtain long-term pedigree data.Extra-pair reproduction is widespread in sociall y monogamous birds.Based on the 6-year pedigree data of a population of Tibetan ground tits(Pseudopodoces humilis)in Changdu,eastern Tibet,this paper estimated the heritabilit y of extra-pair reproductive behavior using animal model approaches.The results are summarized as follows:(1)The proportion of broods containing extra-pair offspring in the population varied between 37.8%and 73.2%(53.0±11.9%).The proportion of extra-pair offspring varied between 28.8%and 42.9%(34.45±4.84%).(2)Both male and female extra-pair copulation behavior can improved fitness in terms of lifetime reproductive success.(3)Extra-pair reproduction had a much low heritabilit y(h~2),0.0015 and0.0014 for numbers of extra-pair copulations and extra-pair offspring in males,respectively,and the corresponding values were 0.0012 and 0.0021 in females.Annual average number of offspring were not heritable with the estimated heritability being0.0017 in males and 0.0018 in females,although their addictive genetic variances(V_A)0.54 for males and 0.35 for females,were non-zero.Our results suggest that extra-pair reproduction in ground tits can increase individual fitness,but the behavior seems not to experience natural selection given the absence of heritabilit y.Instead,the occurrence of extra-pair reproduction is more likel y to be affected by environmental variation.Nevertheless,the b ehavior still remains an evolutionary potential in the ground tit population.