Sexual fidelity trade-offs promote regulatory variation in the prairie vole brain

Individual variation in social behavior seems ubiquitous, but we know little about how it relates to brain diversity. Among monogamous prairie voles, levels of vasopressin receptor (encoded by the gene avpr1a) in brain regions related to spatial memory predict male space use and sexual fidelity in the field. We find that trade-offs between the benefits of male fidelity and infidelity are reflected in patterns of territorial intrusion, offspring paternity, avpr1a expression, and the evolutionary fitness of alternative avpr1a alleles. DNA variation at the avpr1a locus includes polymorphisms that reliably predict the epigenetic status and neural expression of avpr1a, and patterns of DNA diversity demonstrate that avpr1a regulatory variation has been favored by selection. In prairie voles, trade-offs in the fitness consequences of social behaviors seem to promote neuronal and molecular diversity.

社会行为的个体差异普遍存在，但我们对其与大脑多样性之间的关联仍知之甚少。针对一夫一妻制的草原田鼠（prairie voles），研究发现：由基因avpr1a编码的加压素受体（vasopressin receptor）在空间记忆相关脑区中的表达水平，可预测野外雄性的空间利用模式与配偶忠诚度。我们的研究显示，雄性配偶忠诚与不忠的收益权衡，体现在领地入侵模式、后代父权、avpr1a表达量，以及不同avpr1a等位基因的进化适合度（evolutionary fitness）中。avpr1a基因座（locus）的DNA变异包含可稳定预测avpr1a表观遗传状态（epigenetic status）与神经表达量的多态性（polymorphisms）；而DNA多样性模式表明，avpr1a的调控变异受到了选择的青睐。在草原田鼠中，社会行为的适合度后果所带来的权衡，似乎推动了神经元与分子多样性的形成。