Data from: Ecological co-associations influence species’ responses to past climatic change: an example from a Sonoran Desert bark beetle

Ecologically interacting species may have phylogeographic histories that are shaped both by features of their abiotic landscape, and by biotic constraints imposed by their co-association. The Baja California peninsula provides an excellent opportunity to examine the influence of abiotic vs. biotic factors on patterns of diversity in plant-insect species. This is because past climatic and geological changes impacted the genetic structure of plants quite differently to that of co-distributed free-living animals (e.g., herpetofauna and small mammals). Thus, ‘plant-like’ patterns should be discernible in host-specific insect herbivores. Here we investigate the population history of a monophagous bark beetle, Araptus attenuatus, and consider drivers of phylogeographic patterns in light of previous work on its host plant, Euphorbia lomelii. Based on mitochondrial and nuclear markers, we found that the evolutionary history of A. attenuatus exhibits similarities to host plant that are attributable to both biotic and abiotic processes. Southward range expansion and recent colonization of continental Sonora peninsula appear to be unique to this taxon pair, and likely reflect influences of the host plant. On the other hand, abiotic factors with landscape-level influences on suites of co-distributed taxa, such as Plio- and Pleistocene-aged marine incursions in the region, also left genetic signatures in beetle populations. Superimposed on these similarities, bark beetle-specific patterns and processes were also evident. Taken together, this work illustrates that the evolutionary history of species-specific insect herbivores may represent a mosaic of influences, including—but not limited to—those imposed by the host plant.

存在生态互作关系的物种，其谱系地理学历史（phylogeographic history）同时受非生物景观特征，以及其协同互作关系所带来的生物制约因素共同塑造。下加利福尼亚半岛（Baja California peninsula）为探究非生物与生物因子对植物-昆虫类群多样性格局的影响提供了绝佳研究契机。这是因为过往的气候与地质变化，对植物遗传结构的影响模式与同域分布的自由生活动物（如爬行动物区系（herpetofauna）和小型哺乳类）截然不同。因此，寄主专一性植食性昆虫的类群中，应能观测到‘类植物’的演化格局。本研究针对单食性树皮甲虫细角梢小蠹（Araptus attenuatus）的种群历史展开探究，并结合其寄主植物大戟（Euphorbia lomelii）的既往研究结果，分析其谱系地理学格局的驱动因子。基于线粒体与核分子标记，我们发现细角梢小蠹的演化历史与其寄主植物存在相似性，这种相似性可归因于生物与非生物两类过程。向南的种群扩张以及对索诺拉大陆半岛的近期定殖，似乎是该寄主-昆虫类群对所独有的特征，且可能反映了寄主植物带来的影响。另一方面，对同域分布类群具有景观尺度影响的非生物因子——如该区域上新世（Plio-）与更新世（Pleistocene）时期的海洋侵入事件——同样在甲虫种群中留下了遗传印记（genetic signatures）。在这些相似性之上，树皮甲虫特有的模式与过程也同样显著。综合来看，本研究表明，物种专一性植食性昆虫的演化历史，可能是多种影响因子共同构成的镶嵌体，其中包括但不限于寄主植物施加的选择压力。