Department of Marine Science, University of Otago, Dunedin, New Zealand.
Department of Marine Science, University of Otago, Dunedin, New Zealand; Department of Zoology, University of Otago, Dunedin, New Zealand.
Curr Biol. 2022 Jul 25;32(14):3154-3160.e3. doi: 10.1016/j.cub.2022.05.035. Epub 2022 Jun 8.
Globally, species distributions are shifting in response to environmental change, and those that cannot disperse risk extinction. Many taxa, including marine species, are showing poleward range shifts as the climate warms. In the Southern Hemisphere, however, circumpolar oceanic fronts can present barriers to dispersal. Although passive, southward movement of species across this barrier has been considered unlikely, the recent discovery of buoyant kelp rafts on beaches in Antarctica demonstrates that such journeys are possible. Rafting is a key process by which diverse taxa-including terrestrial, e.g., Lindo, Godinot, and Censky et al., and marine, e.g., Carlton et al. and Gillespie et al. species-can cross oceans. Kelp rafts can carry passengers and thus can act as vectors for long-distance dispersal of coastal organisms. The small numbers of kelp rafts previously found in Antarctica do not, however, shed much light on the frequency of such dispersal events. We use a combination of high-resolution phylogenomic analyses (>220,000 SNPs) and oceanographic modeling to show that long-distance biological dispersal events in Southern Ocean are not rare. We document tens of kelp (Durvillaea antarctica) rafting events of thousands of kilometers each, over several decades (1950-2019), with many kelp rafts apparently still reproductively viable. Modeling of dispersal trajectories from genomically inferred source locations shows that distant landmasses are well connected, for example South Georgia and New Zealand, and the Kerguelen Islands and Tasmania. Our findings illustrate the power of genomic approaches to track, and modeling to show frequencies of, long-distance dispersal events.
全球范围内，物种分布正在发生变化以应对环境变化，那些无法扩散的物种面临灭绝的风险。随着气候变暖，许多生物类群，包括海洋物种，正在向极地迁徙。然而，在南半球，环极海洋锋面可能成为扩散的障碍。尽管物种被动地向南穿越这一障碍的可能性不大，但最近在南极洲海滩上发现的漂浮海带筏表明，这种迁徙是可能的。筏运是一个关键的过程，通过这个过程，包括陆地生物，如林多、戈丁诺和森斯基等人，以及海洋生物，如卡尔顿等人和吉莱斯皮等人的多种生物类群可以穿越海洋。海带筏可以搭载乘客，因此可以作为沿海生物远距离扩散的载体。然而，之前在南极洲发现的少量海带筏并不能说明这种扩散事件的频率。我们使用高分辨率系统基因组学分析（>220,000 个 SNP）和海洋学模型的组合来表明，南大洋的远距离生物扩散事件并不罕见。我们记录了数十次海带（Durvillaea antarctica）筏运事件，每次数千公里，跨越几十年（1950-2019 年），许多海带筏显然仍然具有生殖能力。从基因组推断的源位置的扩散轨迹建模表明，遥远的大陆之间连接良好，例如南乔治亚和新西兰，以及凯尔盖朗群岛和塔斯马尼亚。我们的发现说明了基因组方法在追踪和建模远距离扩散事件的频率方面的强大功能。
