Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
School of Environment and Life Sciences, The University of Salford, Manchester, M5 4WT, UK.
J Chem Ecol. 2015 Oct;41(10):871-83. doi: 10.1007/s10886-015-0631-5. Epub 2015 Sep 26.
Chemical communication is the oldest form of communication, spreading across all forms of life. In insects, cuticular hydrocarbons (CHC) function as chemical cues for the recognition of mates, species, and nest-mates in social insects. Although much is known about the function of individual hydrocarbons and their biosynthesis, a phylogenetic overview is lacking. Here, we review the CHC profiles of 241 species of Hymenoptera, one of the largest and most important insect orders, which includes the Symphyta (sawflies), the polyphyletic Parasitica (parasitoid wasps), and the Aculeata (wasps, bees, and ants). We investigated whether these taxonomic groups differed in the presence and absence of CHC classes and whether the sociality of a species (solitarily vs. social) had an effect on CHC profile complexity. We found that the main CHC classes (i.e., n-alkanes, alkenes, and methylalkanes) were all present early in the evolutionary history of the Hymenoptera, as evidenced by their presence in ancient Symphyta and primitive Parasitica wasps. Throughout all groups within the Hymenoptera, the more complex a CHC the fewer species that produce it, which may reflect the Occam's razor principle that insects' only biosynthesize the most simple compound that fulfil its needs. Surprisingly, there was no difference in the complexity of CHC profiles between social and solitary species, with some of the most complex CHC profiles belonging to the Parasitica. This profile complexity has been maintained in the ants, but some specialization in biosynthetic pathways has led to a simplification of profiles in the aculeate wasps and bees. The absence of CHC classes in some taxa or species may be due to gene silencing or down-regulation rather than gene loss, as demonstrated by sister species having highly divergent CHC profiles, and cannot be predicted by their phylogenetic history. The presence of highly complex CHC profiles prior to the vast radiation of the social Hymenoptera indicates a 'spring-loaded' system where the diversity of CHC needed for the complex communication systems of social insects were already present for natural selection to act upon, rather than having evolved independently. This diversity may have aided the multiple independent evolution of sociality within the Aculeata.
化学通讯是最古老的通讯形式，遍布所有生命形式。在昆虫中，角质层烃 (CHC) 作为识别配偶、物种和社会性昆虫中巢伴的化学线索。尽管人们对个别烃类及其生物合成的功能了解很多，但缺乏系统发育概述。在这里，我们回顾了膜翅目 241 种昆虫的 CHC 图谱，膜翅目是最大和最重要的昆虫目之一，包括缨尾目（叶蜂）、多系寄生目（寄生蜂）和针尾目（黄蜂、蜜蜂和蚂蚁）。我们调查了这些分类群是否在 CHC 类别的存在和不存在方面存在差异，以及物种的社会性（独居与群居）是否对 CHC 图谱复杂性产生影响。我们发现，主要的 CHC 类（即正构烷烃、烯烃和甲基烷烃）在膜翅目的进化历史早期就已经存在，这可以从它们在古老的缨尾目和原始寄生蜂中存在得到证明。在膜翅目所有群体中，CHC 越复杂，产生它的物种就越少，这可能反映了奥卡姆剃刀原则，即昆虫只合成满足其需求的最简单的化合物。令人惊讶的是，群居和独居物种的 CHC 图谱复杂性没有差异，其中一些最复杂的 CHC 图谱属于寄生目。这种图谱复杂性在蚂蚁中得以维持，但生物合成途径的某些特化导致了针尾目黄蜂和蜜蜂中图谱的简化。某些分类群或物种中 CHC 类别的缺失可能是由于基因沉默或下调而不是基因丢失，这可以从姐妹物种具有高度分化的 CHC 图谱中得到证明，并且不能通过其系统发育历史来预测。在社会性膜翅目大量辐射之前，高度复杂的 CHC 图谱的存在表明了一种“弹簧加载”系统，即社会性昆虫复杂通讯系统所需的 CHC 多样性已经存在，以便自然选择发挥作用，而不是独立进化。这种多样性可能有助于针尾目昆虫中社会性的多次独立进化。
