Data from: Genotypic diversity enhances invasive ability of Spartina alterniflora

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.

尽管遗传多样性对于需要适应全新环境的外来物种而言至关重要，但学界对于遗传多样性在其入侵成功过程中所发挥的作用仍知之甚少。本研究设置了包含三个基因型多样性梯度的操控实验，以验证基因型多样性能否提升外来物种的入侵能力——本研究的受试物种为中国入侵种互花米草（Spartina alterniflora），并解析其潜在作用机制。实验第一年，基因型多样性与各项生长性能指标之间未呈现显著关联；但自第二年夏季起，基因型多样性使六项性能指标中的四项得到显著提升。经过两个生长季后，基因型多样性与最大扩散距离、斑块面积、单斑块分蘖数以及地上生物量均呈现显著正相关关系。此外，随着互花米草基因型多样性的提升，本土优势物种海三棱藨草（Scirpus mariqueter）的丰度呈现边际显著下降趋势，这表明互花米草入侵能力的增强可能抑制了本土物种的生长。六个基因型间的多数生长性能指标并无显著差异，但我们在多基因型斑块中观测到四项指标呈现超亲生长表现（transgressive over performance）。实验结束时，经蒙特卡罗置换检验（Monte Carlo permutations）分析，六基因型样地中存在基因型多样性的显著非加性效应，而三基因型样地则未呈现该效应。本研究结果表明，加性效应与非加性效应均在遗传多样性与入侵成功的正相关关系中发挥作用，且非加性效应的强度随实验时长增加而增强。