Data from: Baby on board: olfactory cues indicate pregnancy and foetal sex in a nonhuman primate

Olfactory cues play an integral, albeit underappreciated, role in mediating vertebrate social and reproductive behaviour. These cues fluctuate with the signaler’s hormonal condition, coincident with and informative about relevant aspects of its reproductive state, such as pubertal onset, change in season and, in females, timing of ovulation. Although pregnancy dramatically alters a female’s endocrine profiles, which can be further influenced by foetal sex, the relationship between gestation and olfactory cues is poorly understood. We therefore examined the effects of pregnancy and foetal sex on volatile genital secretions in the ring-tailed lemur (Lemur catta), a strepsirrhine primate possessing complex olfactory mechanisms of reproductive signaling. Whilst pregnant, dams altered and dampened their expression of volatile chemicals, with compound richness being particularly reduced in dams bearing sons. These changes were comparable in magnitude to other, published chemical differences among lemurs that are salient to conspecifics. Such olfactory ‘signatures’ of pregnancy may help guide social interactions, potentially promoting mother-infant recognition, reducing intragroup conflict, or counteracting behavioural mechanisms of paternity confusion; cues that also advertise foetal sex may additionally facilitate differential sex allocation.

尽管长期未被充分重视，但嗅觉线索（olfactory cues）在介导脊椎动物社会与繁殖行为的过程中始终发挥着不可或缺的核心作用。这类线索会随信号发出者的激素状态发生波动，且与该个体繁殖状态的关键节点高度同步并能传递相关信息，例如青春期启动、季节更替，以及雌性的排卵时间。尽管妊娠会显著改变雌性的内分泌特征，且胎儿性别会进一步影响这一过程，但目前学界对妊娠与嗅觉线索之间的关联仍知之甚少。为此，我们以环尾狐猴（Lemur catta）——一种具备复杂繁殖信号嗅觉传递机制的原猴亚目灵长类动物——为研究对象，探究了妊娠与胎儿性别对其挥发性生殖器分泌物的影响。妊娠期间，雌性亲代会改变并抑制其挥发性化学物质的表达，其中诞下雄性幼崽的雌性的化合物丰度降低尤为显著。这类变化的幅度与已发表文献中报道的、对狐猴同种个体具有显著生物学意义的种群间化学差异相当。这类妊娠相关的嗅觉‘特征信号’或可指导社会互动，潜在地促进母婴识别、降低群体内部冲突，或抵消父权混淆的行为机制；而能够传递胎儿性别的线索还可能助力差异化的性别资源分配。