Data from: Odor diversity decreases with inbreeding in the ant Hypoponera opacior

Reduction in heterozygosity can lead to inbreeding depression. This loss of genetic variability especially affects diverse loci, such as immune genes or those encoding recognition cues. In social insects, nestmates are recognized by their odor, i.e. their cuticular hydrocarbon profile. Genes underlying hydrocarbon production are thought to be under balancing selection. If so, inbreeding should result in a loss of chemical diversity. We show here that cuticular hydrocarbon diversity decreases with inbreeding. Studying an ant with a facultative inbreeding lifestyle we found inbred workers to exhibit both a lower number of hydrocarbons and less diverse, that is, less evenly-proportioned profiles. The association with inbreeding was strong for methyl-branched alkanes, which play a major role in nestmate recognition, and for n-alkanes, whereas unsaturated compounds were unaffected. Shifts in allocation strategies with inbreeding in our focal species indicate that these ants can detect their inbreeding level and use this information to adjust their reproductive strategy. Our study is the first to demonstrate that odor profiles can encode information on inbreeding, with broad implications not only for social insects, but for sexual selection and mate choice in general. Odor profiles may constitute an honest signal of inbreeding, a fitness-relevant trait in many species.杂合性（heterozygosity）降低可引发近交衰退（inbreeding depression）。这种遗传变异的丧失尤其会影响多类基因座，例如免疫基因或编码识别信号的基因。在社会性昆虫中，巢友通过其气味——即表皮碳氢化合物谱（cuticular hydrocarbon profile）——进行识别。学界普遍认为，调控碳氢化合物合成的基因处于平衡选择（balancing selection）之下。若该推论成立，近交应会导致化学多样性的丧失。本研究证实，表皮碳氢化合物的多样性随近交程度升高而降低。通过研究一种营兼性近交生活方式的蚂蚁，我们发现近交工蚁不仅表皮碳氢化合物的种类更少，其谱式的多样性也更低，即组分比例更为不均。这种关联在巢友识别（nestmate recognition）中发挥核心作用的甲基支链烷烃（methyl-branched alkanes）以及正构烷烃（n-alkanes）中尤为显著，而不饱和化合物（unsaturated compounds）则未受影响。本研究目标物种中，近交引发的资源分配策略改变表明，这些蚂蚁能够检测自身的近交水平，并利用该信息调整繁殖策略。本研究首次证明，气味谱可编码近交水平相关信息，其影响不仅局限于社会性昆虫领域，更对一般性的性选择与配偶选择研究具有广泛意义。气味谱或可作为近交程度的诚实信号，而近交本身便是诸多物种中与适合度密切相关的重要性状。