Department of Evolutionary Anthropology, Duke University, Durham, NC, USA.
Philos Trans R Soc Lond B Biol Sci. 2012 Jul 5;367(1597):1909-22. doi: 10.1098/rstb.2011.0225.
Signal complexity has been linked to social complexity in vocal, but not chemical, communication. To address this gap, we examined the chemical complexity of male and female glandular secretions in eight species of Eulemur. In this diverse clade of macrosmatic primates, species differ by social or mating system and dominance structure. We applied principal component and linear discriminate analyses to data obtained by gas chromatography/mass spectrometry. Beyond the significant effects on chemical signals of gland type, sex, season and species, we found effects of social variables and phylogeny. Notably, female odours were more chemically complex in multimale-multifemale species than pair-bonded species, whereas male odours were more chemically complex in codominant species than female-dominant species. Also, the traditional sexual dimorphism, whereby male signal complexity exceeds that of females, was present in codominant species, but reversed in female-dominant species. Lastly, a positive relationship between the species' pairwise chemical distances and their pairwise phylogenetic distances supported a gradual, but relatively fast mode of signal evolution. We suggest that the comparative method can be a powerful tool in olfactory research, revealing species differences relevant to the understanding of current signal utility and evolutionary processes. In particular, social complexity in lemurs may have selected for olfactory complexity.
信号复杂性与声音中的社会复杂性有关，但与化学通讯无关。为了解决这一差距，我们研究了八种环尾狐猴雄性和雌性腺分泌物的化学复杂性。在这个具有大嗅觉能力的灵长类动物多样化的分支中，物种在社会或交配系统以及优势结构上存在差异。我们应用主成分和线性判别分析对气相色谱/质谱获得的数据进行了分析。除了腺体类型、性别、季节和物种对化学信号的显著影响外，我们还发现了社会变量和系统发育的影响。值得注意的是，在多雄性-多雌性物种中，雌性气味比一夫一妻制物种的化学复杂性更高，而在共位优势物种中，雄性气味比雌性优势物种的化学复杂性更高。此外，传统的性别二态性，即雄性信号复杂性超过雌性，存在于共位优势物种中，但在雌性优势物种中则相反。最后，物种间化学距离的成对和它们间系统发育距离的成对呈正相关，支持了信号进化的渐进但相对较快的模式。我们认为，比较方法可以成为嗅觉研究的有力工具，揭示与理解当前信号效用和进化过程相关的物种差异。特别是，狐猴的社会复杂性可能选择了嗅觉的复杂性。
