Sterck E H M, Bontrop R E, de Groot N, de Vos-Rouweler A J M, Doxiadis G G M
Department of Animal Ecology, Utrecht University, Utrecht, The Netherlands.
Department of Animal Science, Ethology, Biomedical Primate Research Centre, Rijswijk, The Netherlands.
Mol Ecol. 2017 Jul;26(14):3785-3793. doi: 10.1111/mec.14153. Epub 2017 Jun 21.
The heterozygosity status of polymorphic elements of the immune system, such as the major histocompatibility complex (MHC), is known to increase the potential to cope with a wider variety of pathogens. Pre- and postcopulatory processes may regulate MHC heterozygosity. In a population where mating occurs among individuals that share identical MHC haplotypes, postcopulatory selection may disfavour homozygous offspring or ones with two MHC haplotypes identical to its mother. We tested these ideas by determining the incidence of MHC-heterozygous and MHC-homozygous individuals in a pedigreed, partially consanguineous captive rhesus monkey colony. Bayesian statistics showed that when parents share MHC haplotypes, the distribution of MHC-heterozygous and MHC-homozygous individuals significantly fitted the expected Mendelian distribution, both for the complete MHC haplotypes, and for MHC class I or II genes separately. Altogether, we found in this captive colony no evidence for postcopulatory selection against MHC-homozygous individuals. However, the distribution of paternally and maternally inherited MHC haplotypes tended to differ significantly from expected. Individuals with two MHC haplotypes identical to their mother were underrepresented and offspring with MHC haplotypes identical to their father tended to be overrepresented. This suggests that postcopulatory processes affect MHC haplotype combination in offspring, but do not prevent low MHC heterozygosity.
已知免疫系统多态性元件的杂合状态，如主要组织相容性复合体（MHC），会增加应对更广泛病原体的潜力。交配前和交配后的过程可能会调节MHC杂合性。在一个由具有相同MHC单倍型的个体之间进行交配的种群中，交配后选择可能不利于纯合后代或具有与其母亲相同的两个MHC单倍型的后代。我们通过确定一个有谱系的、部分近亲繁殖的圈养恒河猴群体中MHC杂合个体和MHC纯合个体的发生率来检验这些想法。贝叶斯统计表明，当父母共享MHC单倍型时，MHC杂合个体和MHC纯合个体的分布对于完整的MHC单倍型以及分别对于MHC I类或II类基因均显著符合预期的孟德尔分布。总体而言，我们在这个圈养群体中没有发现交配后针对MHC纯合个体进行选择的证据。然而，父系和母系遗传的MHC单倍型的分布往往与预期有显著差异。具有与其母亲相同的两个MHC单倍型的个体数量不足，而具有与其父亲相同的MHC单倍型的后代往往数量过多。这表明交配后过程会影响后代的MHC单倍型组合，但不会阻止低MHC杂合性。
