Data from: Hybridization alters early life-history traits and increases plant colonization success in a novel region

Hybridization is hypothesized to promote invasiveness, but empirical tests comparing the performance of hybrid versus parental taxa in novel regions are lacking. We experimentally compared colonization ability of populations of wild radish (Raphanus raphanistrum) versus populations of advanced-generation hybrids between wild and cultivated radish (R. sativus) in a southeast Texas pasture, well beyond the known invasive range of hybrid radish. We also manipulated the strength of interspecific competition to better generalize across variable environments. In both competitive environments, hybrid populations produced at least three times more seeds than wild radish populations, a distinction that was driven by greater hybrid seedling emergence, earlier hybrid emergence and more hybrid seedlings surviving to flower, rather than by greater individual fecundity. Flowering duration in hybrids was less negatively affected by competition than it was in wild radishes, while early emergence was associated with subsequent high seed output in both biotypes. Our data show that hybridization can enhance colonization success in a novel region, and, by comparison with previous studies, that the life-history traits enhancing hybrid success can differ across regions, even for lineages originating from the same hybridization event. These results imply a much larger arena for hybrid success than previously appreciated.

杂交被假设可提升物种的入侵潜力，但目前仍缺乏针对新生境中杂交类群与亲本类群表现开展直接对比的实证检验。本研究于德克萨斯州东南部一处牧场开展控制实验，对比了野萝卜（Raphanus raphanistrum）种群与野萝卜和栽培萝卜（R. sativus）的高级世代杂交种种群的定殖能力——该牧场远超出已记录的杂交萝卜入侵分布范围。我们通过操控种间竞争强度，以提升研究结果在异质环境中的普适性。在两种竞争环境下，杂交种种群的种子总产量至少为野萝卜种群的3倍，该差异主要源于杂交种更高的幼苗出苗率、更早的出苗时间以及更多存活至开花阶段的杂交幼苗，而非单株繁殖力的提升。杂交种的开花时长受竞争的负面影响程度显著低于野萝卜；且两种生物型中，早期出苗均与后续较高的种子产量呈显著正相关。本研究结果表明，杂交作用可增强类群在新生境中的定殖成功率；结合既往研究来看，即便源自同一杂交事件的谱系，助力杂交种获得成功的生活史性状也可能因地域不同而存在差异。上述结果意味着杂交类群实现成功入侵的潜在生态空间远大于此前的认知。