Diversity at the Major Histocompatibility Complex (MHC) is critical to health and fitness, such that MHC genotype may predict an individual’s quality or compatibility as a competitor, ally, or mate. Moreover, because MHC products can influence the components of bodily secretions, an individual’s body odors may signal its MHC composition and influence partner identification or mate choice. Here, we investigated MHC-based signaling and recipient sensitivity by testing for odor-gene covariance and behavioral discrimination of MHC diversity and pairwise dissimilarity in a strepsirrhine primate, the ring-tailed lemur (Lemur catta). First, we coupled genotyping of the MHC class II gene, DRB, with gas chromatography-mass spectrometry of genital gland secretions to investigate if functional genetic diversity is signaled by the chemical diversity of lemur scent secretions. We also assessed if the chemical similarity between individuals correlated with their MHC-DRB similarity. Next, we assessed if lemurs discriminated this chemically encoded, genetic information in opposite-sex conspecifics. We found that both sexes signaled overall MHC-DRB diversity and pairwise MHC-DRB similarity via genital secretions, but in a sex- and season-dependent manner. Additionally, the sexes discriminated absolute and relative MHC-DRB diversity in the genital odors of opposite-sex conspecifics, suggesting that lemur genital odors function to advertise genetic quality. In summary, genital odors of ring-tailed lemurs provide honest information about an individual’s absolute and relative MHC quality. Complementing evidence in humans and Old World monkeys, we suggest that reliance on scent signals to communicate MHC quality may be important across the primate lineage.

中文翻译：

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MHC II 类基因座的遗传变异影响环尾狐猴的嗅觉信号和气味辨别

主要组织相容性复合物 (MHC) 的多样性对于健康和健身至关重要，因此 MHC 基因型可以预测个体作为竞争对手、盟友或配偶的品质或兼容性。此外，由于 MHC 产品可以影响身体分泌物的成分，因此个体的体味可能会发出其 MHC 成分的信号，并影响伴侣识别或配偶选择。在这里，我们通过测试链尾狐猴 (Lemur catta) 的气味基因协方差和 MHC 多样性的行为辨别以及成对差异来研究基于 MHC 的信号传导和接受者敏感性。首先，我们将 MHC II 类基因 DRB 的基因分型与生殖腺分泌物的气相色谱-质谱联用，以研究狐猴气味分泌物的化学多样性是否表明功能性遗传多样性。我们还评估了个体之间的化学相似性是否与其 MHC-DRB 相似性相关。接下来，我们评估了狐猴是否能够区分异性同种动物中的这种化学编码的遗传信息。我们发现，两性都通过生殖器分泌物表达了总体 MHC-DRB 多样性和成对 MHC-DRB 相似性，但以性别和季节依赖性方式。此外，性别区分异性同种生殖器气味的绝对和相对 MHC-DRB 多样性，这表明狐猴生殖器气味具有宣传遗传质量的功能。总之，环尾狐猴的生殖器气味提供了有关个体绝对和相对 MHC 质量的真实信息。作为对人类和旧世界猴子的证据的补充，我们认为依靠气味信号来传达 MHC 质量可能在整个灵长类谱系中很重要。