Chemical communication plays a pivotal role in shaping sexual and ecological interactions among animals. In lizards, fundamental mechanisms of sexual selection such as female mate choice have rarely been shown to be influenced by quantitative phenotypic traits (e.g., ornaments), while chemical signals have been found to potentially influence multiple forms of sexual and social interactions, including mate choice and territoriality. Chemical signals in lizards are secreted by glands primarily located on the edge of the cloacae (precloacal glands, PG) and thighs (femoral glands), and whose interspecific and interclade number ranges from 0 to > 100. However, elucidating the factors underlying the evolution of such remarkable variation remains an elusive endeavour. Competing hypotheses suggest a dominant role for phylogenetic conservatism (i.e., species within clades share similar numbers of glands) or for natural selection (i.e., their adaptive diversification results in deviating numbers of glands from ancestors). Using the prolific Liolaemus lizard radiation from South America (where PG vary from 0 to 14), we present one of the largest-scale tests of both hypotheses to date. Based on climatic and phylogenetic modelling, we show a clear role for both phylogenetic inertia and adaptation underlying gland variation: (i) solar radiation, net primary productivity, topographic heterogeneity and precipitation range have a significant effect on PG variation, (ii) humid and cold environments tend to concentrate species with a higher number of glands, (iii) there is a strong phylogenetic signal that tends to conserve the number of PG within clades. Collectively, our study confirms that the inertia of niche conservatism can be broken down by the need of species facing different selection regimes to adjust their glands to suit the demands of their specific environments.

中文翻译：

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蜥蜴化学通讯的宏观生态学：气候因素是否驱动信号腺的进化？


化学通讯在塑造动物之间的性和生态相互作用方面发挥着关键作用。在蜥蜴中，性选择的基本机制（例如雌性配偶选择）很少被证明受到数量表型特征（例如装饰品）的影响，而化学信号被发现可能影响多种形式的性和社会互动，包括配偶选择和领土性。蜥蜴的化学信号由主要位于泄殖腔边缘（泄殖腔前腺，PG）和大腿（股腺）的腺体分泌，其种间和进化枝数范围从 0 到 > 100。然而，阐明进化背后的因素如此显着的变化仍然是一项难以捉摸的努力。相互竞争的假设表明，系统发育保守性（即，进化枝内的物种共享相似数量的腺体）或自然选择（即，它们的适应性多样化导致腺体数量偏离祖先）的主导作用。利用来自南美的多产Liolaemus蜥蜴辐射（其中 PG 从 0 到 14），我们提出了迄今为止对这两种假设最大规模的检验之一。基于气候和系统发育模型，我们显示了腺体变化背后的系统发育惰性和适应性的明确作用：（i）太阳辐射、净初级生产力、地形异质性和降水范围对PG变化有显着影响，（ii）潮湿和寒冷环境倾向于集中具有较多腺体数量的物种，(iii)存在强烈的系统发育信号，倾向于保留进化枝内的 PG 数量。 总的来说，我们的研究证实，生态位保守主义的惯性可以通过面临不同选择制度的物种调整其腺体以适应其特定环境的需求的需要来打破。