Data_Sheet_5_Life-history traits drive spatial genetic structuring in Dinaric cave spiders.PDF

The subterranean ecosystem exerts strong selection pressures on the organisms that thrive in it. In response, obligate cave-dwellers have developed a series of morphological, physiological, and behavioral adaptations, such as eye reduction, appendage elongation, low metabolic rates or intermittent activity patterns, collectively referred to as troglomorphism. Traditionally, studies on cave organisms have been hampered by the difficulty of sampling (i.e., small population sizes, temporal heterogeneity in specimen occurrence, challenges imposed by the difficult-to-access nature of caves). Here, we circumvent this limitation by implementing a museomics approach. Specifically, we aim at comparing the genetic population structures of five cave spider species demonstrating contrasting life histories and levels of troglomorphism across different caves in the northern Dinarides (Balkans, Europe). We applied a genome-wide hybridization-capture approach (i.e., HyRAD) to capture DNA from 117 historical samples. By comparing the population genetic structures among five species and by studying isolation by distance, we identified deeper population structuring and more pronounced patterns of isolation by distance in the highly troglomorphic Parastalita stygia and Stalita pretneri ground dwellers, while the three web-building Troglohyphantes species, two of which can occasionally be found in surface habitats, showed less structured populations compatible with higher dispersal ability. The spatial distribution of genetic groups revealed common phylogeographic breaks among lineages across the studied species, which hint at the importance of environmental features in driving dispersal potential and shaping underground diversity.

地下生态系统对在此繁衍的生物施加了极强的选择压力。专性洞居生物因此演化出一系列形态、生理及行为适应性特征，诸如眼部退化、附肢延长、低代谢速率或间歇性活动模式，这类特征统称为洞穴适应性（troglomorphism）。传统上，洞穴生物研究常受限于采样难题：种群规模微小、标本出现的时间异质性，以及洞穴难以进入的特性所带来的挑战。本研究通过运用博物馆基因组学（museomics）方法规避了这一局限。具体而言，本研究旨在对比欧洲巴尔干半岛迪纳拉山脉北部不同洞穴中5种洞穴蜘蛛的种群遗传结构，这些物种展现出迥异的生活史与洞穴适应性水平。我们采用全基因组杂交捕获技术（HyRAD），从117份历史标本中捕获DNA。通过对比5个物种的种群遗传结构并开展距离隔离效应分析，我们发现，在洞穴适应性极强的Parastalita stygia与Stalita pretneri（均为陆栖洞穴蜘蛛）中，种群结构更为显著，距离隔离模式也更为突出；而3种结网的Troglohyphantes属物种（其中两种偶尔可在地表生境中发现）的种群结构则相对较弱，这与其更强的扩散能力相符。遗传类群的空间分布显示，所有研究物种的谱系间均存在共同的系统地理断裂，这暗示环境特征在调控扩散潜力、塑造地下生物多样性方面发挥着重要作用。