Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan.
Institute of Mountain Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan.
Proc Biol Sci. 2023 Apr 26;290(1997):20230177. doi: 10.1098/rspb.2023.0177. Epub 2023 Apr 19.
Floods affect the population structure of organisms that inhabit streams. In recent decades, the scale of floods has become larger due to climate change. Under these circumstances, on 12 October 2019, the largest typhoon in the history of observation in Japan struck the Japanese Archipelago. This typhoon caused heavy rainfall in various places, and the Chikuma-Shinano River System (Japan's largest) suffered great damage. Eight years before the large-scale disturbance in the river system, the population structure of the mayfly was studied in detail using quantitative sampling (population numbers and biomass) and by sequencing the mtDNA cytochrome c oxidase subunit I. To understand the impact of the flood on the population and genetic structures, we repeated the same research approximately 1 year after the flood. Direct comparison of sites before and after the flood revealed no significant changes between pre- and post-flood population genetic structure. This indicates high resistance and/or resilience recovery of the populations to the disturbance. We hypothesize that this high resistance/resilience to flood disturbance is a result of strong selection for such traits in the rivers of the Japanese Archipelago, which are short, steep, flow rapidly and violently, and are strongly affected by floods.
洪水会影响栖息在溪流中的生物的种群结构。近几十年来，由于气候变化，洪水的规模变得更大了。在这种情况下，2019 年 10 月 12 日，日本有观测记录以来最大的台风袭击了日本列岛。这场台风导致各地降雨量很大，而筑波-信浓水系（日本最大的水系）遭受了巨大的破坏。在该水系发生大规模干扰的 8 年前，使用定量采样（种群数量和生物量）和 mtDNA 细胞色素 c 氧化酶亚基 I 测序对蜉蝣的种群结构进行了详细研究。为了了解洪水对种群和遗传结构的影响，我们大约在洪水发生一年后重复了这项研究。洪水前后地点的直接比较表明，洪水前后的种群遗传结构没有显著变化。这表明，种群对干扰具有很高的抵抗力和/或恢复力。我们假设，这种对洪水干扰的高抵抗力/恢复力是日本列岛河流的强烈选择的结果，这些河流短、陡峭、流速快且猛烈，并且受到洪水的强烈影响。
