Department of Integrative Biology, Museum of Vertebrate Zoology, University of California, Berkeley, California, United States of America.
PLoS One. 2012;7(5):e37562. doi: 10.1371/journal.pone.0037562. Epub 2012 May 23.
Reproductive behavior may play an important role in shaping selection on Major Histocompatibility Complex (MHC) genes. For example, the number of sexual partners that an individual has may affect exposure to sexually transmitted pathogens, with more partners leading to greater exposure and, hence, potentially greater selection for variation at MHC loci. To explore this hypothesis, we examined the strength of selection on exon 2 of the MHC-DQα locus in two species of Peromyscus. While the California mouse (P. californicus) is characterized by lifetime social and genetic monogamy, the deer mouse (P. maniculatus) is socially and genetically promiscuous; consistent with these differences in mating behavior, the diversity of bacteria present within the reproductive tracts of females is significantly greater for P. maniculatus. To test the prediction that more reproductive partners and exposure to a greater range of sexually transmitted pathogens are associated with enhanced diversifying selection on genes responsible for immune function, we compared patterns and levels of diversity at the Class II MHC-DQα locus in sympatric populations of P. maniculatus and P. californicus. Using likelihood based analyses, we show that selection is enhanced in the promiscuous P. maniculatus. This study is the first to compare the strength of selection in wild sympatric rodents with known differences in pathogen milieu.
生殖行为可能在塑造 MHC 基因选择方面发挥重要作用。例如，个体拥有的性伴侣数量可能会影响其对性传播病原体的暴露程度，性伴侣越多，暴露程度就越高，因此 MHC 基因座的变异可能受到更大的选择压力。为了探索这一假设，我们研究了两种 Peromyscus 鼠（加州鼠和鹿鼠）MHC-DQα 基因外显子 2 上的选择强度。加州鼠表现出终生的社会和遗传一夫一妻制，而鹿鼠则具有社会和遗传上的滥交行为；与这些交配行为的差异一致，鹿鼠生殖道内的细菌多样性明显大于加州鼠。为了检验以下预测，即更多的性伴侣和接触更多种类的性传播病原体与负责免疫功能的基因的多样化选择增强有关，我们比较了生活在同一地区的鹿鼠和加州鼠的 MHC-DQα 基因座的模式和多样性水平。通过基于似然的分析，我们表明在滥交的鹿鼠中选择得到了增强。这项研究首次比较了具有已知病原体环境差异的野生同域啮齿动物的选择强度。
