Mutualisms are mediated by adaptive traits of interacting organisms and play a central role in the ecology and evolution of species. Thousands of plant species possess tiny structures called “domatia” that house mites which protect plants from pests, yet these traits remain woefully understudied. Here, we release a worldwide database of species with mite domatia and provide an evaluation of the phylogenetic and geographic distribution of this mutualistic trait. With >2,500 additions based on digital herbarium scans and published reports, we increased the number of known species with domatia by 27% and, importantly, documented their absence in >4,000 species. We show that mite domatia likely evolved hundreds of times among flowering plants, occurring in an estimated ~10% of woody species representing over a quarter of all angiosperm families. Contrary to classic hypotheses about the evolutionary drivers of mutualism, we find that mite domatia evolved more frequently in temperate regions and in deciduous lineages; this pattern is concordant with a large-scale geographic transition from predominantly ant-based plant defense mutualisms in the tropics to mite-based defense mutualisms in temperate climates. Our data also reveal a pattern of evolutionary convergence in domatia morphology, with tuft-form domatia more likely to evolve in dry temperate habitats and pit domatia more likely to evolve in wet tropical environments. We have shown climate-associated drivers of mite domatia evolution, demonstrating their utility and power as an evolutionarily replicated system for the study of plant defense mutualisms.

中文翻译：

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植物-螨共生关系及其生态驱动因素的全球评估


共生是由相互作用生物体的适应性特征介导的，并在物种的生态学和进化中起着核心作用。数以千计的植物物种具有称为“domatia”的微小结构，这些结构容纳了螨虫，可以保护植物免受害虫侵害，但这些特性仍然没有得到充分的研究。在这里，我们发布了一个全球性的螨虫物种数据库，并提供了对这种共生性状的系统发育和地理分布的评估。根据数字植物标本馆扫描和已发表的报告，增加了 >2,500 个物种，我们将已知具有 domatia 的物种数量增加了 27%，重要的是，在 >4,000 个物种中记录了它们的缺失。我们表明，螨虫 domatia 可能在开花植物中进化了数百次，估计发生在 ~10% 的木本物种中，占所有被子植物科的四分之一以上。与关于共生进化驱动因素的经典假设相反，我们发现螨虫 domatia 在温带地区和落叶谱系中进化得更频繁;这种模式与从热带地区主要以蚂蚁为基础的植物防御共生关系向温带气候中以螨虫为基础的防御互生关系的大规模地理转变相一致。我们的数据还揭示了 domatia 形态的进化趋同模式，簇状 domatia 更有可能在干燥的温带栖息地中进化，而坑状 domatia 更有可能在潮湿的热带环境中进化。我们已经展示了螨虫 domatia 进化的气候相关驱动因素，证明了它们作为进化复制系统研究植物防御共生关系的效用和力量。