Coutellec-Vreto Marie-Agnès, Jarne Philippe, Guiller Annie, Madec Luc, Daguzan Jacques
Department of Population Biology, Zoological Institute, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen ϕ, Denmark.
Laboratoire Génétique et Environnement-CC 065, Institut des Sciences de l'Evolution, Université Montpellier II, 34095, Montpellier cedex 05, France.
Evolution. 1998 Dec;52(6):1635-1647. doi: 10.1111/j.1558-5646.1998.tb02244.x.
Inbreeding depression was estimated from an outbreeding population of the freshwater snail Lymnaea peregra, on the basis of two successive generations of enforced selling and outcrossing, and 70 maternal lineages. Outcrossing was analyzed under two treatments, groups of two and five individuals. The fitness parameters measured included fecundity, growth, and survival. In the first generation, we contrasted three treatments (selfers vs. paired outcrossers and group outcrossers). Very similar results were obtained between the two outcrossing treatments. A strong self-fertilization depression (which includes parental fecundity and progeny fitness) was detected in the selling treatment (about 90%). In the second generation, there was again marked evidence for self-fertilization depression, with the highest contributions coming from parental fecundity and progeny hatching rate. Our results suggest that the decreased parental fecundity is a consequence of the mating system in the previous generation, although the role of partial self-incompatibility and the copulation behavior could not be ruled out. Hatching rate and early survival data are suggestive of purging of lethal mutations. Significant variation in fitness among selfing lineages was found for most fitness traits. Our experimental design also allowed to test for interactions among fitness loci. Only one trait of the nine studied behaved as expected under synergistic interactions. However we cannot rule out some purging during the experiment, which could have biased results towards linearity. Inbreeding depression was also inferred from the change of inbreeding level across generations in the same population. We obtained a value similar to the experimental estimate.
基于连续两代的强制自交和杂交以及70个母系谱系，从淡水蜗牛欧洲椎实螺的一个远交群体中估算了近亲繁殖衰退。在两种处理方式下分析了杂交情况，即两个个体一组和五个个体一组。所测量的适合度参数包括繁殖力、生长和存活情况。在第一代，我们对比了三种处理方式（自交个体与配对杂交个体和群体杂交个体）。两种杂交处理方式得到了非常相似的结果。在自交处理中检测到强烈的自交衰退（包括亲本繁殖力和后代适合度）（约90%）。在第二代，再次有明显的自交衰退证据，最大的影响来自亲本繁殖力和后代孵化率。我们的结果表明，亲本繁殖力下降是上一代交配系统的结果，尽管部分自交不亲和性和交配行为的作用不能排除。孵化率和早期存活数据表明存在致死突变的清除。在大多数适合度性状上，自交谱系之间的适合度存在显著差异。我们的实验设计还允许测试适合度基因座之间的相互作用。在所研究的九个性状中，只有一个性状在协同相互作用下表现符合预期。然而，我们不能排除实验过程中的一些清除作用，这可能使结果偏向线性。近亲繁殖衰退也从同一群体中各代近亲繁殖水平的变化中推断出来。我们得到了一个与实验估计值相似的值。
