Jokiniemi Annalaura, Turunen Tanja, Kohonen Mikko, Magris Martina, Ritari Jarmo, Kuusipalo Liisa, Partanen Jukka, Kekäläinen Jukka
Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland.
Finnish Red Cross Blood Service, Research and Development, Helsinki, Finland.
Heredity (Edinb). 2025 May 9. doi: 10.1038/s41437-025-00759-9.
Major histocompatibility complex (MHC) genes are known to mediate mate choice both at the individual and gamete level. However, it has remained unclear how different episodes of MHC-associated mate choice interact and contribute to the total selection on MHC genes. Here, we clarified this interaction in humans by performing a full-factorial experiment where 10 females first ranked the attractiveness and intensity of the body odours of 11 males. Then we studied whether female odour preferences in these same 110 male-female combinations predicted sperm performance in the presence of follicular fluid (sperm-stimulating female reproductive fluid). When analyzing the total MHC similarity (including classical and non-classical MHC genes) of the male-female combinations, we found that females preferred the body odours of MHC-similar males, but that sperm motility was positively affected by the MHC dissimilarity of the male-female combinations. No associations were found for classical MHC genes only. Furthermore, odour preferences were negatively associated with sperm motility at the end of the follicular fluid treatment. Together, our results indicate that individual and gamete-level mate choice processes may act in opposing directions and that the most attractive males are not necessarily the most optimal partners at the post-copulatory level. Finally, our findings suggest that gamete-mediated mate choice may have a definitive role in disfavouring genetically incompatible partners from fertilizing oocytes.
主要组织相容性复合体（MHC）基因在个体和配子水平上都参与配偶选择。然而，目前尚不清楚与MHC相关的不同配偶选择过程是如何相互作用并对MHC基因的整体选择产生影响的。在此，我们通过一项全因子实验阐明了人类中的这种相互作用。在该实验中，10名女性首先对11名男性的体味吸引力和强度进行了排序。然后，我们研究了在这些相同的110种男女组合中，女性的气味偏好是否能预测在卵泡液（刺激精子的女性生殖液）存在的情况下精子的性能。在分析男女组合的总MHC相似性（包括经典和非经典MHC基因）时，我们发现女性更喜欢MHC相似男性的体味，但精子活力受到男女组合MHC差异的正向影响。仅针对经典MHC基因未发现关联。此外，在卵泡液处理结束时，气味偏好与精子活力呈负相关。总之，我们的结果表明，个体和配子水平的配偶选择过程可能作用方向相反，而且最具吸引力的男性在交配后水平上不一定是最优伴侣。最后，我们的研究结果表明，配子介导的配偶选择可能在阻止基因不相容的伴侣使卵母细胞受精方面具有决定性作用。
