Genetics of hybrid male sterility between drosophila sibling species: a complex web of epistasis is revealed in interspecific studies.
Genetics of hybrid male sterility between drosophila sibling species: a complex web of epistasis is revealed in interspecific studies.
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果蝇同胞物种之间杂种雄性不育的遗传学：种间研究揭示了复杂的上位性网络。
DOI：
10.1093/genetics/138.2.329
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发表时间：
1994
期刊：
影响因子：
3.3
通讯作者：
Wu,CI
中科院分区：
文献类型：
--
作者：
Palopoli,MF;Wu,CI
为了研究其雄性杂交后代不育的遗传差异，我们将来自模拟果蝇的X染色体的小片段渗入到纯的毛里求斯果蝇遗传背景中，然后评估携带不同大小的异源基因渗入的雄性的生育力。虽然这项分析只检查了不到20%的X染色体（大约是D染色体常染色质部分的5%）。simulans基因组），并且所述片段仅在一个方向上渗入，揭示了导致杂种雄性不育的至少四个因子。至少有两个因素表现出很强的上位性：男性携带任何因素单独一致的生育能力，而男性携带两个因素在一起总是不育。不同长度的不育渐渗观察到不同的生精表型，它似乎渐渗片段之间的相互作用也影响生精缺陷的阶段。具有一类基因渗入的雄性通常产生大量活动精子并观察到交配，但从未使雌性授精。显然，这两个物种在大量的位点上发生了分歧，这些位点对杂种雄性育性有不同的影响。通过外推，我们估计仅在X染色体上就至少有40个这样的基因座。由于这些物种在任意选择的基因座上表现出很小的DNA序列差异，因此观察到的广泛的功能差异似乎不太可能主要是由于随机遗传漂变。同种基因之间的上位性似乎是一个共同的组成部分杂交不育最近分化的果蝇物种之间。互作因子的连锁关系可以揭示上位性选择在导致物种间生殖障碍的等位基因替换动态中所起的作用。
To study the genetic differences responsible for the sterility of their male hybrids, we introgressed small segments of an X chromosome from Drosophila simulans into a pure Drosophila mauritiana genetic background, then assessed the fertility of males carrying heterospecific introgressions of varying size. Although this analysis examined less than 20% of the X chromosome (roughly 5% of the euchromatic portion of the D. simulans genome), and the segments were introgressed in only one direction, a minimum of four factors that contribute to hybrid male sterility were revealed. At least two of the factors exhibited strong epistasis: males carrying either factor alone were consistently fertile, whereas males carrying both factors together were always sterile. Distinct spermatogenic phenotypes were observed for sterile introgressions of different lengths, and it appeared that an interaction between introgressed segments also influenced the stage of spermatogenic defect. Males with one category of introgression often produced large quantities of motile sperm and were observed copulating, but never inseminated females. Evidently these two species have diverged at a large number of loci which have varied effects on hybrid male fertility. By extrapolation, we estimate that there are at least 40 such loci on the X chromosome alone. Because these species exhibit little DNA-sequence divergence at arbitrarily chosen loci, it seems unlikely that the extensive functional divergence observed could be due mainly to random genetic drift. Significant epistasis between conspecific genes appears to be a common component of hybrid sterility between recently diverged species of Drosophila. The linkage relationships of interacting factors could shed light on the role played by epistatic selection in the dynamics of the allele substitutions responsible for reproductive barriers between species.