Studies on effects of the outbreeding depression on reproduction and regeneration of rare tree species grown in wet lands

我们研究了生长在湿地上的稀有树种由于远距离杂交和种群间杂交而导致的远交衰退的影响。由于种群间在早期生命阶段的适合性成分(果花比和种子/胚珠比)上的交叉，以及种群内交配距离与幼苗生长量呈负相关，因此红枫树表现出异交衰退。另一方面，木兰树在生命早期并未因种群间杂交而表现出远缘繁殖衰退。在一个孤立的狼毒种群中，种群间杂交对树木的适合度成分产生了积极的影响(即杂种优势)，而不是负面的影响(远交抑制)。

We examined effects of outbreeding depression due to long-distance crossing and inter-population crossing in rare tree species grown in wet lands. Acer pycnunthum trees exhibited outbreeding depression due to inter-population crossing in fitness components at the early life stage (fruit/flower ratio and seed/ovule ratio) and negative correlation between distance between mates and growth increment for its seedlings within a population. On the other hand, Magnolia stellata trees did not exhibit outbreeding depression due to inter-population crossing at the early life stage. The inter-population crossing resulted in positive effects (i.e., heterosis) rather than negative effects (outbreeding depression) on the fitness components of trees in an isolated M. stellata population.