WSL Swiss Federal Research Institute, Birmensdorf, Switzerland.
Oecologia. 2011 Oct;167(2):427-34. doi: 10.1007/s00442-011-1985-1. Epub 2011 Apr 12.
Plants flowering together may influence each other's pollination and fecundity over a range of physical distances. Their effects on one another can be competitive, neutral, or facilitative. We manipulated the floral neighborhood of the high-alpine cushion plant Eritrichium nanum in the Swiss Alps and measured the effects of co-flowering neighbors on both the number of seeds produced and the degree of inbreeding and outbreeding in the offspring, as deduced from nuclear microsatellite markers. Seed set of E. nanum did not vary significantly with the presence or absence of two Saxifraga species growing as near neighbors, but it was higher in E. nanum cushions growing at low conspecific density than in those growing at high density. In addition, floral neighborhood had no detectable effect on the degree of selfing of E. nanum, but seeds from cushions growing at low conspecific density were more highly outbred than seeds from cushions at high density. Thus, there was no evidence of either competition or facilitation between E. nanum and Saxifraga spp. as mediated by pollinators at the spatial scale of our experimental manipulation. In contrast, the greater fecundity of E. nanum cushions at low density was consistent with reduced intraspecific competition for pollinators and might also represent a beneficial effect of highly outbred seeds as brought about by more long-distance pollinator flights under low-density conditions.
聚在一起的植物可能会在一定的物理距离范围内影响彼此的传粉和繁殖能力。它们之间的相互作用可能是竞争、中性或促进的。我们在瑞士阿尔卑斯山的高山垫状植物 Eritrichium nanum 中操纵了其花邻域，并通过核微卫星标记测量了共同开花的邻居对其产生的种子数量和后代的自交和异交程度的影响。E. nanum 的结实率与两种近邻生长的 Saxifraga 物种的存在与否没有显著差异，但在低同种密度生长的 E. nanum 垫中高于在高同种密度生长的垫中。此外，花邻域对 E. nanum 的自交程度没有明显影响，但在低同种密度生长的垫中产生的种子比在高同种密度生长的垫中产生的种子更具异交性。因此，在我们实验操作的空间尺度上，没有证据表明 E. nanum 和 Saxifraga spp. 之间存在竞争或促进作用。相比之下，低密度下 E. nanum 垫的更高繁殖力与同种内竞争减少有关，也可能代表了在低密度条件下，由于远距离传粉者飞行增加，高度异交的种子带来的有益效应。
