Complex selection on a regulator of social cognition: evidence of balancing selection, regulatory interactions and population differentiation in the prairie vole Avpr1a locus

Adaptive variation in social behavior depends upon standing genetic variation, but we know little about how evolutionary forces shape genetic diversity relevant to brain and behavior. In prairie voles (Microtus ochrogaster), variants at the Avpr1a locus predict expression of the vasopressin 1a receptor in the retrosplenial cortex (RSC), a brain region that mediates spatial and contextual memory; cortical V1aR abundance in turn predicts diversity in space-use and sexual fidelity in the field. To examine the potential contributions of adaptive and neutral forces to variation at the Avpr1a locus, we explore sequence diversity at the Avpr1a locus and throughout the genome in two populations of wild prairie voles. First, we refine results demonstrating balancing selection at the locus by comparing the frequency spectrum of variants at the locus to a random sample of the genome. Next, we find that the four SNPs that predict high V1aR expression in the RSC are in stronger linkage disequilibriu...社会行为的适应性变异依赖于现存遗传变异，但我们对进化力量如何塑造与大脑及行为相关的遗传多样性仍知之甚少。在草原田鼠（Microtus ochrogaster）中，Avpr1a基因座（Avpr1a locus）的变异可预测 retrosplenial 皮层（retrosplenial cortex, RSC）内的血管加压素1a受体表达水平——该脑区介导空间与情境记忆；而皮层V1a受体丰度又可预测野生种群的空间利用模式与性忠贞程度差异。为探究适应性与中性进化力量对Avpr1a基因座变异的潜在贡献，我们对两个野生草原田鼠种群的Avpr1a基因座及全基因组序列多样性展开分析。首先，通过对比该基因座变异的频率频谱与基因组随机样本，我们进一步完善了该基因座存在平衡选择的研究结论。其次，我们发现，4种可预测 retrosplenial 皮层内高V1a受体表达的单核苷酸多态性（Single Nucleotide Polymorphisms, SNPs）处于更强的连锁不平衡状态……