Ludwig-Maximilians-Universität, Department Biologie II, Evolutionsökologie, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany.
Mol Ecol. 2010 Oct;19(19):4168-78. doi: 10.1111/j.1365-294X.2010.04807.x. Epub 2010 Sep 3.
Hybridization is common among cyclical parthenogens, especially in zooplankton species assemblages of the genus Daphnia. To explore hybridization dynamics and the extent of clonal diversity in the Daphnia longispina complex, we analysed population structure in eight permanent lakes. Based on 15 microsatellite loci, three major taxonomic units emerged: two species, D. galeata and D. longispina and their F1 hybrids, supported by factorial correspondence analysis and two Bayesian methods. At the same time, the detection of backcross classes differed between methods. Mean clonal diversity was lowest in the F1 hybrids, as expected from the high rate of asexual reproduction. Within taxa, replicated genotypes were of clonal origin, but clonal lineages persisted in subsequent years in only one of three resampled lakes. In another lake, the taxon composition changed from being dominated by hybrids to complete dominance by one parental taxon. Such a year-to-year taxon replacement has not been reported for the D. longispina complex before. Our data on this hybrid complex illustrate that high-resolution genotyping is essential for the understanding of ecological and evolutionary outcomes of hybridization in partially clonal taxa.
杂交在周期性孤雌生殖生物中很常见，尤其是在枝角类浮游动物物种组合中。为了探索 Daphnia longispina 复合体中的杂交动态和克隆多样性程度，我们分析了八个永久性湖泊的种群结构。基于 15 个微卫星基因座，我们发现有三个主要的分类单元：两个物种，D. galeata 和 D. longispina 及其 F1 杂种，这一结果得到了因子对应分析和两种贝叶斯方法的支持。同时，不同方法对回交类别的检测结果存在差异。预期 F1 杂种具有高的无性繁殖率，因此其克隆多样性最低。在分类单元内，重复的基因型具有克隆起源，但在随后的年份中，只有三个重采样湖泊中的一个保留了克隆谱系。在另一个湖泊中，分类单元的组成从以杂种为主转变为完全由一个亲代分类单元主导。在 D. longispina 复合体中，以前没有报道过这种逐年的分类单元更替。我们对这个杂交复合体的数据表明，高分辨率基因分型对于理解部分克隆类群中杂交的生态和进化结果至关重要。
