Tectonic evolution of the Tethyan region created the Eurasian extratropical biodiversity hotspots: tracing Pireneitega spiders' diversification history

The withdrawal of the Tethys Sea and the formation of the Alpine-Himalayan orogenic belt profoundly impacted the distribution and composition of terrestrial biota in Eurasia. However, studies that have explicitly addressed the potential links between the series of tectonic activities in the Tethyan region and the formation of extratropical biodiversity hotspots in the Alpine-Himalayan belt are rare. The Pireneitega spiders (Agelenidae) are found throughout Eurasia and show high species richness in these hotspots. Thus, using Pireneitega spiders as a model group, we can shed light on how past tectonic events shaped Eurasian hotspots. To reconstruct the spatial and temporal evolution of Pireneitega spp., an integrative historical biogeographical analysis has been conducted using thousands of novel DNA sequences and five novel transcriptome sequences from different species. Species distribution modelling based on complete geographical distribution information was used to assess the ecological preferences and the potential ecological interchangeability of Pireneitega species. Our study suggests that the rapid expansion of Pireneitega in Eurasia benefitted from the Tethys Sea regression in the early Oligocene. Most Pireneitega species are distributed allopatrically, but in similar niches. The diversification of Pireneitega species relied on invading numerous new isolated habitats created by the uplift of Alpine-Himalayan mountains during the Miocene (wet valley model). These results imply that the formation of Alpine-Himalayan hotspots was driven by the series of tectonic events in the Tethyan region during the Oligocene–Miocene.

特提斯海（Tethys Sea）的退却与阿尔卑斯-喜马拉雅造山带（Alpine-Himalayan orogenic belt）的形成，深刻影响了欧亚大陆陆地生物群的分布与组成。然而，目前鲜有研究明确探讨特提斯洋域一系列构造活动与阿尔卑斯-喜马拉雅带温带生物多样性热点形成之间的潜在关联。拟隙蛛属（Pireneitega）蜘蛛隶属于漏斗蛛科（Agelenidae），广泛分布于欧亚大陆，且在上述生物多样性热点区域物种丰富度极高。因此，以拟隙蛛属蜘蛛作为研究模式类群，我们可阐明过往构造事件如何塑造欧亚大陆的生物多样性热点区域。为重建拟隙蛛属物种的时空演化格局，本研究基于不同物种的数千条全新DNA序列与5条全新转录组序列，开展了整合式历史生物地理学分析；同时基于完整地理分布信息构建物种分布模型，以评估拟隙蛛属物种的生态偏好与潜在生态位互换性。研究结果显示，拟隙蛛属在欧亚大陆的快速扩张得益于渐新世（Oligocene）早期特提斯海的退缩。绝大多数拟隙蛛属物种呈异域分布，但栖息于相似的生态位；其物种分化依赖于中新世（Miocene）时期阿尔卑斯-喜马拉雅山脉隆升所形成的大量新生孤立生境（湿谷模型）。上述结果表明，阿尔卑斯-喜马拉雅生物多样性热点的形成，由渐新世至中新世特提斯洋域的一系列构造活动所驱动。