Department of Environmental Sciences, East China Normal University, Shanghai 200062, China.
Mol Ecol. 2012 May;21(10):2542-51. doi: 10.1111/j.1365-294X.2012.05531.x. Epub 2012 Mar 13.
Although genetic diversity is very important for alien species, which have to cope with new environments, little is known about the role that genetic diversity plays in their invasive success. In this study, we set up a manipulation experiment including three levels of genotypic diversity to test whether genotypic diversity can enhance the invasive ability of alien species, in our case the invasive Spartina alterniflora in China, and to infer the underlying mechanisms. There was no significant relationship between genotypic diversity and parameters of performance in the first year; however, from the summer of the second year onwards, genotypic diversity enhanced four of the six parameters of performance. After two growing seasons, there were significant positive relationships between genotypic diversity and maximum spread distance, patch size, shoot number per patch, and aboveground biomass. Moreover, abundance of the native dominant species Scirpus mariqueter was marginally significantly decreased with genotypic diversity of S. alterniflora, suggesting that enhanced invasive ability of S. alterniflora may have depressed the growth of the native species. There was no significant difference in most measures of performance among six genotypes, but we observed a transgressive over performance in four measures in multiple-genotype patches. At the end of the experiment, there were significant nonadditive effects of genotypic diversity according to Monte Carlo permutations, in six-genotype, but not three-genotype plots. Our results indicated that both additive and nonadditive effects played roles in the positive relationship between genetic diversity and invasion success, and nonadditive effects were stronger as duration increased.
尽管遗传多样性对必须应对新环境的外来物种非常重要，但人们对外来物种遗传多样性在其入侵成功中所起的作用知之甚少。在本研究中，我们设计了一个包含三个基因型多样性水平的操纵实验，以测试基因型多样性是否可以增强外来物种（本案例为入侵中国的互花米草）的入侵能力，并推断其潜在机制。在第一年，基因型多样性与表现参数之间没有显著关系；然而，从第二年夏天开始，基因型多样性增强了表现参数中的六个中的四个。经过两个生长季节，基因型多样性与最大扩散距离、斑块大小、每个斑块的芽数和地上生物量之间呈显著正相关。此外，随着互花米草基因型多样性的增加，本地优势种芦苇的丰度略有显著降低，表明互花米草增强的入侵能力可能抑制了本地物种的生长。六个基因型中大多数表现参数之间没有显著差异，但我们在多基因型斑块中观察到四个表现参数存在超亲优势。在实验结束时，根据蒙特卡罗置换法，六基因型斑块存在显著的非加性效应，但三基因型斑块不存在。我们的结果表明，加性和非加性效应对遗传多样性与入侵成功之间的正相关关系都有作用，并且非加性效应随着时间的增加而增强。
