Temporal changes in the genetic structure of the Daphnia species complex in Tjeukemeer, with evidence for backcrossing
Temporal changes in the genetic structure of the Daphnia species complex in Tjeukemeer, with evidence for backcrossing
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DOI：
10.1038/hdy.1996.77
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发表时间：
1996-05
期刊：
影响因子：
3.8
通讯作者：
P. Spaak
中科院分区：
文献类型：
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作者：
P. Spaak
研究了位于Tjeukemeer湖（荷兰）的循环单性生殖盔形水蚤-兜水蚤物种复合体的时间遗传变异。连续3年对3个等位酶位点进行了研究，以比较D. galeata（G）、盾壳霉D. cucullata（C）及其种间杂种（C× G）。该数据集被用来调查：C× G杂种是否经常产生的亲本物种和回交发生在这个物种复合体的程度。G和C× G是最丰富的类群，而C仅在夏末和秋季丰富。遗传多样性以C最高，G最低，C× G居中。C× G的pgm和pgi等位基因频率不介于亲本之间，但与G的相似性大于C。此外，几乎没有观察到与Hardy-Weinberg的显著偏差。Nei's遗传距离的UPGMA分析表明，C× G杂种与G的亲缘关系较近（差异< 0.04），与C的亲缘关系较近（差异0.30）。我的数据表明，与其他研究相一致，C× G杂种可能仍然由亲本物种形成，尽管不一定每年都有。此外，我的数据表明，回交频繁发生，并导致C等位基因渗入G。
Temporal genetic variation was studied within the cyclic parthenogenetic Daphnia galeata-cucullata species complex in Lake Tjeukemeer (The Netherlands). During three successive years, three allozyme loci were studied in order to compare the level of genetic variation in D. galeata (G), D. cucullata (C) and their interspecific hybrid (C× G). This data set was used to investigate: whether C× G hybrids are regularly produced by the parental species and to what extent backcrossing takes place in this species complex. G and C× G were the most abundant taxa, whereas C was only abundant in late summer and autumn. Genetic diversity was highest in C, lowest in G, and intermediate in C× G. pgm and pgi allele frequencies of C× G were not intermediate to those of the parental species but were more similar to G than to C. In addition, almost no significant deviations from Hardy-Weinberg were observed. An UPGMA analysis of Nei's genetic distances showed that C× G hybrids are more closely related to G (difference< 0.04), than to C (difference 0.30). My data suggest, in accordance with other studies, that C× G hybrids are probably still formed by the parental species, though not necessarily every year. Furthermore, my data suggest that backcrossing occurred frequently, and led to introgression of C alleles into G.