Van Der Hulst R G, Mes T H, Den Nijs J C, Bachmann K
Institute for Systematics and Ecology, University of Amsterdam, Kruislaan 318, NL-1098 SM Amsterdam, The Netherlands.
Mol Ecol. 2000 Jan;9(1):1-8. doi: 10.1046/j.1365-294x.2000.00704.x.
Highly variable amplified fragment length polymorphism (AFLP) fingerprints of triploid apomictic dandelions obtained from three localities in an area where diploids are lacking were analysed to infer the predominant modes of reproduction. The distribution of markers was analysed using character compatibility to infer whether many genotypes agree with a tree-like structure in the data set. The presence of incompatible character state combinations (matrix incompatibility; MI) was used as a measure of genetic exchange. The detection of overrepresented genotypes, of which some were widespread, confirmed asexual reproduction. Not all genotypes were overrepresented; approximately half of the genotypes in the three localities were found only once. Because, in terms of genotype frequencies, only a part of the genetic variation is described, more important aspects of the molecular data such as relationships between markers or genotypes have been studied. The analysis of character compatibility indicated a disagreement of the data with a clonal structure. Nearly all genotypes contributed to MI and this contribution varied considerably among genotypes in each sampled locality. A gradual decrease of matrix incompatibility upon successive deletion of genotypes showing the highest contribution to MI indicated that marker distribution of virtually all genotypes disagreed with a tree-like structure in the data. This result suggested that many genotypes were separated by one or more sexual generations. Consistent with this conclusion was the fact that markers that show a low probability of contributing to MI are different in every sampled locality, which is most easily explained as the result of recombination. Apparently, asexual reproduction has resulted in overrepresented, widespread genotypes but sexual recombination has also substantially contributed to genetic variation in the sites studied.
对从一个缺乏二倍体的地区的三个地点获得的三倍体无融合生殖蒲公英的高度可变扩增片段长度多态性（AFLP）指纹图谱进行分析，以推断主要的繁殖方式。使用性状相容性分析标记的分布，以推断数据集中是否有许多基因型符合树状结构。不相容性状状态组合（矩阵不相容性；MI）的存在被用作遗传交换的一种度量。对过度代表性基因型（其中一些分布广泛）的检测证实了无性繁殖。并非所有基因型都是过度代表性的；在这三个地点中，大约一半的基因型只被发现过一次。由于就基因型频率而言，只描述了部分遗传变异，因此对分子数据的更重要方面，如标记或基因型之间的关系进行了研究。性状相容性分析表明数据与克隆结构不一致。几乎所有基因型都对MI有贡献，并且这种贡献在每个采样地点的基因型之间有很大差异。在连续删除对MI贡献最大的基因型后，矩阵不相容性逐渐降低，这表明几乎所有基因型的标记分布都与数据中的树状结构不一致。这一结果表明许多基因型被一个或多个有性世代分隔开。与此结论一致的是，在每个采样地点，对MI贡献概率低的标记是不同的，这最容易解释为重组的结果。显然，无性繁殖导致了过度代表性、分布广泛的基因型，但有性重组也对所研究地点的遗传变异有很大贡献。
