Living on the edge genomic and ecological delineation of cryptic lineages in the high-elevation specialist Erebia nivalis

Cold adapted species of high elevations may be especially impacted by global warming since they might be limited in their capacity to adapt to changing conditions, or might be prevented from shifting their distributions upwards if no suitable habitats are available.The latter might be true for Erebia nivalis, a high-elevation specialist that mainly occurs in the Austrian Alps and on few mountaintops in Switzerland, where its taxonomic and conservation status remains unclear.We aimed to clarify the relationship of geographically isolated populations of E. nivalis using whole-genome resequencing data to reconstruct population connectivity and phylogenetic relationships. We inferred current and historical effective population sizes and combined these with tests for ecological differentiation based on available occurrence data, to re-evaluate the conservation status of E. nivalis.Our results confirm that Swiss and Austrian E. nivalis subspecies should be considered different evolutionary significant units, marked by moderate genomic differentiation, distinct demographic histories and a difference in the abiotic conditions of their habitats. These subspecies should be treated as independent units for conservation purposes.In both subspecies, we found rapid uphill range shifts over the last decades, little population connectivity, low current effective population sizes and low genetic diversity, especially in Switzerland. The above, combined with the low dispersal capacity of this two-year lifecycle species, and its need to overwinter under snow, which is rapidly retreating from several regions of the Alps, leads us to suggest that the status of E. nivalis should be updated to Vulnerable or Endangered in the European, Swiss and Austrian Red Lists.

高海拔冷适应物种可能受全球变暖的影响尤为显著：这类物种对环境变化的适应能力存在局限，若缺乏适宜栖息地，还无法向上迁移以调整分布范围。雪红眼蝶（Erebia nivalis）作为高海拔特有物种，主要分布于奥地利阿尔卑斯山区及瑞士少数山顶区域，其分类学与保护现状迄今仍不明晰，上述情况或许正适用于该物种。本研究旨在借助全基因组重测序数据，厘清雪红眼蝶地理隔离种群间的亲缘关系，以重建种群连通性与系统发育关系。我们推断了该物种当前及历史的有效种群大小，并结合基于现有分布记录开展的生态分化检验，重新评估雪红眼蝶的保护等级。研究结果证实，瑞士与奥地利的雪红眼蝶亚种应被视作不同的进化显著单元，二者具有中等程度的基因组分化、截然不同的种群历史，以及栖息地非生物环境的差异。上述亚种应在保护工作中作为独立单元进行管理。在两个亚种中，我们均观测到近数十年来种群分布快速向高海拔迁移的现象，且种群连通性极低；当前有效种群规模与遗传多样性均处于较低水平，瑞士种群尤为显著。结合该物种两年世代周期带来的低扩散能力，以及其依赖积雪越冬的生存需求（而阿尔卑斯山区部分区域的积雪正快速消退），我们建议在欧洲、瑞士及奥地利的红色名录中，将雪红眼蝶的保护等级更新为易危（Vulnerable）或濒危（Endangered）。