Dimattia Lydia M, Saglam Naim, Saunders Ralph, Shain Daniel H
Biology Department, Rutgers The State University of New Jersey, Camden, NJ, 08103, USA.
Department of Aquaculture and Fish Diseases, Fisheries Faculty, Firat University, 23119, Elazig, Türkiye.
Extremophiles. 2025 Jul 10;29(2):30. doi: 10.1007/s00792-025-01390-6.
Bdelloid rotifers are major components of zooplankton worldwide and have been reported in glacier ice in both Northern and Southern Hemispheres. Curiously, no reports of psychrophilic bdelloids have surfaced in North America despite exhaustive surveys of other ice-dwelling invertebrates, e.g., glacier ice worms. This distribution gap may be partially explained by a predator-prey relationship between these two animals, but the current study suggests that ice worms and bdelloids can co-inhabit at least some glacial ecosystems over geological time. Here we report the first ice-inhabiting bdelloid rotifer from North America, collected from the northern aspect of Mt. Deception, WA, USA. Nuclear and mitochondrial genotyping identified sister-species relationships within a clade of Nordic ice-dwelling bdelloids, and close evolutionary relationships with Antarctic/New Zealand specimens. Intrapopulation genetic divergences suggest that bdelloids arrived in North America near the onset of the Pleistocene (2.58 myr BP), but their circumpolar dispersal capabilities and robustness (e.g., freeze-thaw tolerance, ability to propagate at elevated temperatures and under extreme laboratory conditions) cannot rule out multiple transoceanic dispersal events throughout the Quaternary.
蛭形轮虫是全球浮游动物的主要组成部分，在北半球和南半球的冰川冰中均有报道。奇怪的是，尽管对其他栖息于冰中的无脊椎动物，如冰川冰虫进行了详尽的调查，但在北美却没有嗜冷蛭形轮虫的报道。这种分布差异可能部分归因于这两种动物之间的捕食关系，但当前的研究表明，在地质时期，冰虫和蛭形轮虫至少可以共同栖息于一些冰川生态系统中。在此，我们报告了从美国华盛顿州欺骗山北坡采集到的北美首例栖息于冰中的蛭形轮虫。核基因和线粒体基因分型确定了北欧栖息于冰中的蛭形轮虫一个分支内的姐妹物种关系，以及与南极/新西兰标本的密切进化关系。种群内的遗传差异表明，蛭形轮虫在更新世开始时（距今258万年）就抵达了北美，但它们的环极扩散能力和强健性（如耐冻融性、在高温及极端实验室条件下繁殖的能力）并不能排除在整个第四纪期间发生多次跨洋扩散事件的可能性。
