Data from: Kin discrimination via odour in the cooperatively breeding banded mongoose

Kin discrimination is often beneficial for group-living animals as it aids in inbreeding avoidance and providing nepotistic help. In mammals, the use of olfactory cues in kin discrimination is widespread and may occur through learning the scents of individuals that are likely to be relatives, or by assessing genetic relatedness directly through assessing odour similarity (phenotype matching). We use scent presentations to investigate these possibilities in a wild population of the banded mongoose Mungos mungo, a cooperative breeder in which inbreeding risk is high and females breed communally, disrupting behavioural cues to kinship. We find that adults show heightened behavioural responses to unfamiliar (extra-group) scents than to familiar (within-group) scents. Interestingly, we found that responses to familiar odours, but not unfamiliar odours, varied with relatedness. This suggests that banded mongooses are either able to use an effective behavioural rule to identify likely relatives from within their group, or that phenotype matching is used in the context of within-group kin recognition but not extra-group kin recognition. In other cooperative breeders, familiarity is used within the group and phenotype matching may be used to identify unfamiliar kin. However, for the banded mongoose this pattern may be reversed, most likely due to their unusual breeding system which disrupts within-group behavioural cues to kinship.

亲缘识别对群居动物通常具有演化适应性益处，可帮助其规避近交风险并提供亲缘帮扶。在哺乳动物中，亲缘识别广泛依赖嗅觉线索（olfactory cues），其实现路径主要有二：一是通过学习疑似亲属个体的气味，二是通过评估气味相似性直接判断遗传亲缘关系，即表型匹配（phenotype matching）。
本研究通过气味呈现实验，在野生缟獴（banded mongoose, Mungos mungo）种群中验证上述两种假说。缟獴是一种集体繁育的合作性物种，其近交风险较高且雌性个体实行群居繁殖，这一特性破坏了用于亲缘识别的行为线索。
研究发现，成年缟獴对陌生（群外）气味的行为反应强度显著高于熟悉（群内）气味。值得注意的是，仅对熟悉气味的反应强度随遗传亲缘关系程度发生变化，而陌生气味则无此规律。
这一结果表明，缟獴要么可通过有效的行为规则识别群内疑似亲属，要么仅在群内亲缘识别中运用表型匹配策略，而对群外亲缘识别则不采用该策略。在其他合作繁育物种中，群内亲缘识别通常依赖熟悉度线索，而表型匹配则用于识别陌生亲缘个体。但缟獴的亲缘识别模式恰好相反，这极有可能与其独特的繁育系统有关——该系统破坏了群内用于亲缘识别的行为线索。