Willi Yvonne, van Kleunen Mark, Dietrich Stefan, Fischer Markus
Institute of Environmental Sciences, University of Zürich, 8057 Zürich, Switzerland.
Proc Biol Sci. 2007 Sep 22;274(1623):2357-64. doi: 10.1098/rspb.2007.0768.
Habitat fragmentation commonly causes genetic problems and reduced fitness when populations become small. Stocking small populations with individuals from other populations may enrich genetic variation and alleviate inbreeding, but such artificial gene flow is not commonly used in conservation owing to potential outbreeding depression. We addressed the role of long-term population size, genetic distance between populations and test environment for the performance of two generations of offspring from between-population crosses of the locally rare plant Ranunculus reptans L. Interpopulation outbreeding positively affected an aggregate measure of fitness, and the fitness superiority of interpopulation hybrids was maintained in the second offspring (F2) generation. Small populations benefited more strongly from interpopulation outbreeding. Genetic distance between crossed populations in neutral markers or quantitative characters was not important. These results were consistent under near-natural competition-free and competitive conditions. We conclude that the benefits of interpopulation outbreeding are likely to outweigh potential drawbacks, especially for populations that suffer from inbreeding.
当种群规模变小时，栖息地破碎化通常会导致遗传问题并降低适合度。用其他种群的个体对小种群进行补植可能会增加遗传变异并减轻近亲繁殖，但由于潜在的远交衰退，这种人工基因流动在保护中并不常用。我们研究了长期种群规模、种群间遗传距离和测试环境对本地稀有植物匐枝毛茛种群间杂交两代后代表现的作用。种群间远交对适合度的综合指标有积极影响，并且种群间杂种的适合度优势在第二代后代（F2）中得以维持。小种群从种群间远交中受益更为显著。中性标记或数量性状中杂交种群间的遗传距离并不重要。在接近自然的无竞争和有竞争条件下，这些结果都是一致的。我们得出结论，种群间远交的益处可能超过潜在的弊端，特别是对于那些遭受近亲繁殖的种群而言。
