Pearse Ian S, Becker Zoe, Ode Paul J, Gaskin John F, West Natalie M
U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO, USA.
Dept. Agricultural Biology, Colorado State University, Fort Collins, CO, USA.
Am J Bot. 2025 Aug;112(8):e70083. doi: 10.1002/ajb2.70083. Epub 2025 Aug 14.
Clonality, a form of asexual reproduction and spread, is common among invasive plants, though sexual reproduction via seeds is often still important for their long-range dispersal. In small populations, clonality has been hypothesized to interfere with sexual reproduction by limiting outcrossing opportunities of a plant.
We developed a structural equation model based on estimates of genetic diversity and seed production of Lepidium draba, a problematic invasive clonal plant, at 26 sites in Colorado to test whether site characteristics relating to small founder populations resulted in low genetic diversity and sexual reproduction. The next year, in pollen supplementation experiments at six sites (three with high genetic diversity, three with low), we tested whether populations with low genetic diversity were limited by non-self pollen.
Large populations and populations associated with rivers tended to have higher genetic diversity. Percentage seed fill and total seed production were considerably higher at sites with higher genetic diversity. At populations with low genetic diversity, supplementation with pollen from outside of the site, but not from within the site, increased seed production. At populations with high genetic diversity, pollen supplementation from off-site did not increase seed production.
Our study shows that, in low-diversity populations that are dominated by a few large clones, L. draba produces few seeds compared to high-diversity populations and that this appears to be due to limited availability of non-self pollen. The data indicate that low genetic diversity decreases sexual reproduction, which may greatly reduce long-distance dispersal from these populations.
克隆性作为一种无性繁殖和传播方式，在入侵植物中很常见，不过通过种子进行的有性繁殖对于其远距离扩散通常仍很重要。在小种群中，有假说认为克隆性会通过限制植物的异交机会来干扰有性繁殖。
我们基于对科罗拉多州26个地点的有问题的入侵克隆植物——北美独行菜的遗传多样性和种子产量的估计，开发了一个结构方程模型，以测试与小奠基者种群相关的地点特征是否导致了低遗传多样性和有性繁殖。次年，在六个地点（三个高遗传多样性地点、三个低遗传多样性地点）进行的花粉补充实验中，我们测试了低遗传多样性种群是否受到非自身花粉的限制。
大种群以及与河流相关的种群往往具有更高的遗传多样性。在遗传多样性较高的地点，种子饱满率和种子总产量要高得多。在遗传多样性低的种群中，补充来自地点外而非地点内的花粉会增加种子产量。在遗传多样性高的种群中，异地补充花粉并不会增加种子产量。
我们的研究表明，在由少数几个大克隆体主导的低多样性种群中，与高多样性种群相比，北美独行菜产生的种子较少，这似乎是由于非自身花粉的可获得性有限。数据表明，低遗传多样性会降低有性繁殖，这可能会大大减少这些种群的远距离扩散。
