DeWalt R Edward, South Eric J
University of Illinois, Prairie Research Institute, Illinois Natural History Survey, 1816 S Oak St., Champaign, IL 61820, USA.
University of Illinois at Urbana-Champaign, Department of Entomology, 320 Morrill Hall, 505 S. Goodwin Ave., Urbana, IL 61801, USA.
Zookeys. 2015 Nov 5(532):137-58. doi: 10.3897/zookeys.532.6478. eCollection 2015.
Extensive sampling for aquatic insects was conducted in the orders Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) (EPT) of Isle Royale National Park (ISRO), Michigan, United States of America, during summer 2013. The island was ice covered until 8,000 to 10,000 years ago and is isolated by 22-70 km distance from the mainland. Two hypotheses were examined: that ISRO EPT richness would be much reduced from the mainland, and that the species colonizing ISRO would be of smaller size than mainland, adults presumably using updrafts to bridge the distance from mainland sources. Data sets were developed for known mainland EPT species and size for those species. The first hypothesis was confirmed with the mainland species pool consisting of 417 EPT, while ISRO is known to support 73 species. Richness of EPT is directly related to the number of specimens examined. Small streams supported five EPT species, while 15-25 species were found in larger streams. Lakeshores had intermediate diversity. The second hypothesis was substantiated for stoneflies, but not for mayflies or caddisflies. Stoneflies apparently are poorer fliers than either of the other two orders.
2013年夏季，在美国密歇根州皇家岛国家公园（ISRO），针对水生昆虫进行了广泛采样，涉及蜉蝣目（蜉蝣）、襀翅目（石蝇）和毛翅目（石蛾）（EPT）。该岛屿直到8000至10000年前都被冰层覆盖，与大陆相距22 - 70公里，处于隔离状态。研究检验了两个假设：一是皇家岛国家公园的EPT丰富度相比大陆会大幅降低；二是在皇家岛国家公园定殖的物种体型会比大陆的小，成虫大概利用上升气流跨越与大陆源头之间的距离。针对已知的大陆EPT物种及其体型构建了数据集。第一个假设得到证实，大陆物种库中有417种EPT，而皇家岛国家公园已知有73种。EPT丰富度与所检查标本的数量直接相关。小溪中有5种EPT，而较大溪流中有15 - 25种。湖岸的多样性处于中间水平。第二个假设对于石蝇得到证实，但对于蜉蝣或石蛾不成立。石蝇显然比其他两个目更不善于飞行。
