Yiming Li, Zhengjun Wu, Duncan Richard P
Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 25 Beisihuanxi Road, Haidian, 100080, Beijing, China.
Oecologia. 2006 May;148(1):129-36. doi: 10.1007/s00442-006-0355-x. Epub 2006 Feb 3.
Islands are often considered easier to invade than mainland locations because of lower biotic resistance, but this hypothesis is difficult to test. We compared invasion success (the probability of establishing a wild reproducing population) for bullfrogs (Rana catesbeiana) introduced to enclosures on 26 farms on islands in the Zhoushan archipelago and 15 farms in neighboring mainland China. Bullfrogs were more likely to invade farms located on islands with lower native frog species richness than mainland farms, consistent with the biotic resistance hypothesis. However, human frog hunting pressure also differed between islands and the mainland and, along with the number of bullfrogs raised in enclosures, was a stronger predictor of invasion success than native frog richness in multiple regression. Variation in hunting pressure was also able to account for the difference in invasion success between islands and mainlands: islands had lower hunting pressure and thus higher invasion probability. We conclude that the ease with which bullfrogs have invaded islands of the Zhoushan archipelago relative to the mainland has little to do with biotic resistance but results from variation in factors under human control.
由于生物抗性较低，岛屿通常被认为比大陆地区更容易被入侵，但这一假设很难得到验证。我们比较了引入舟山群岛26个岛屿养殖场和邻近中国大陆15个养殖场围栏内牛蛙（美国牛蛙）的入侵成功率（建立野生繁殖种群的概率）。与生物抗性假设一致，牛蛙更有可能入侵本地蛙类物种丰富度低于大陆养殖场的岛屿养殖场。然而，岛屿和大陆的人类捕蛙压力也存在差异，并且在多元回归分析中，与围栏内养殖的牛蛙数量一起，比本地蛙类丰富度更能有力地预测入侵成功率。捕蛙压力的差异也能够解释岛屿和大陆之间入侵成功率的差异：岛屿的捕蛙压力较低，因此入侵概率更高。我们得出结论，相对于大陆，牛蛙入侵舟山群岛岛屿的容易程度与生物抗性几乎无关，而是由人类可控因素的差异导致的。
