Climate, physiological tolerance, and sex-biased dispersal shape genetic structure of Neotropical orchid bees

Understanding the impact of past climatic events on the demographic history of extant species is critical for predicting species’ responses to future climate change. Paleoclimatic instability is a major mechanism of lineage diversification in taxa with low dispersal and small geographic ranges in tropical ecosystems. However, the impact of these climatic events remains questionable for the diversification of species with high levels of gene flow and large geographic distributions. In this study, we investigate the impact of Pleistocene climate change on three Neotropical orchid bee species (Eulaema bombiformis, E. meriana and E. cingulata) with transcontinental distributions and different physiological tolerances. We first generated ecological niche models to identify species-specific climatically stable areas during Pleistocene climatic oscillations. Using a combination of mitochondrial and nuclear markers, we inferred calibrated phylogenies and estimated historical demographic paramet...解析古气候事件对现生物种种群历史的影响，对于预测物种对未来气候变化的响应至关重要。古气候不稳定性（paleoclimatic instability）是热带生态系统中扩散能力较低、地理分布范围狭窄的类群发生谱系分化（lineage diversification）的核心驱动机制。然而，此类气候事件对具有高基因流（gene flow）水平及广域地理分布的物种分化的影响，目前仍存在争议。本研究以三种具有跨大陆分布格局且生理耐受特性各异的新热带区兰花蜂类群（*Eulaema bombiformis*、*E. meriana* 及 *E. cingulata*）为研究对象，探讨更新世（Pleistocene）气候变化对其种群分化的影响。本研究首先构建生态位模型（ecological niche model），以识别更新世气候波动期间各物种专属的气候稳定栖息区域。结合线粒体标记（mitochondrial marker）与核标记（nuclear marker），我们重建了经时间校准的系统发育树（phylogeny），并估算了历史种群动态参数