Annis Water Resources Institute, Grand Valley State University Muskegon, MI, USA ; Department of Biological Sciences, Purdue University West Lafayette, IN, USA.
Evol Appl. 2013 Apr;6(3):462-71. doi: 10.1111/eva.12027. Epub 2012 Nov 16.
Hybridization may stimulate the evolution of invasiveness in human-impacted habitats if unique hybrid genotypes have higher fitness than parental genotypes. Human efforts to control invasive taxa frequently involve the intentional alteration of habitats, but few studies have considered whether hybridization can result in decreased sensitivity to control measures. Here, we investigate whether interspecific hybrids between introduced Eurasian watermilfoil (Myriophyllum spicatum) and native northern watermilfoil (M. sibiricum) are more invasive than parental Eurasian watermilfoil, especially in regard to their relative responses to an herbicide commonly applied for their control (2,4-dichlorophenoxyacetic acid; 2,4-D). In two separate laboratory experiments, hybrids on average grew faster and were less sensitive to 2,4-D compared with parental Eurasian watermilfoil. These two invasive traits appear to be common in hybrid watermilfoils, as opposed to being restricted to a few unique lineages, because they were found in a diversity of hybrid genotypes from several independent hybridization events. In addition, we found that hybrids occurred more frequently than parental species in natural lakes previously treated with 2,4-D. Our results provide compelling empirical evidence that hybridization is associated with the evolution of increased invasiveness in watermilfoils, and have important implications for their management.
杂交可能会刺激人类活动影响的栖息地中入侵性的进化，如果独特的杂交基因型比亲本基因型具有更高的适应性。人类控制入侵性生物的努力经常涉及对栖息地的有意改变，但很少有研究考虑杂交是否会导致对控制措施的敏感性降低。在这里，我们研究了引入的欧亚水蕹菜（Myriophyllum spicatum）和本地北方水蕹菜（M. sibiricum）之间的种间杂种是否比亲本欧亚水蕹菜更具入侵性，特别是在它们对常用于控制的除草剂（2,4-二氯苯氧乙酸；2,4-D）的相对反应方面。在两个独立的实验室实验中，与亲本欧亚水蕹菜相比，杂种的平均生长速度更快，对 2,4-D 的敏感性更低。这两个入侵特征似乎在杂种水蕹菜中很常见，而不是仅限于少数独特的谱系，因为它们存在于来自几个独立杂交事件的多种杂种基因型中。此外，我们发现杂种在以前用 2,4-D 处理过的天然湖泊中比亲本物种更频繁地出现。我们的研究结果提供了令人信服的经验证据，表明杂交与水蕹菜中入侵性增强的进化有关，这对它们的管理具有重要意义。
