Accelerated mitochondrial evolution and "Darwin's corollary":: Asymmetric viability of reciprocal F1 hybrids in centrarchid fishes
Accelerated mitochondrial evolution and "Darwin's corollary":: Asymmetric viability of reciprocal F1 hybrids in centrarchid fishes
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DOI：
10.1534/genetics.107.081364
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发表时间：
2008-02-01
期刊：
影响因子：
3.3
通讯作者：
Near, Thomas J.
中科院分区：
文献类型：
--
作者：
Bolnick, Daniel I.;Turelli, Michael;Near, Thomas J.
物种之间的正反交可以产生具有不同生存能力的杂交种。这种不对称杂交生存能力的高频率(“达尔文的推论”)使其与霍尔丹规则和“大X效应”并驾齐驱，成为后交配生殖隔离的一般特征。最近的理论表明，倒易交叉不对称可能是由于单亲遗传基因座(如线粒体基因组)的随机替换而产生的，尽管线粒体替换率的巨大系统差异也可能导致不对称。尽管在不同物种中，不对称的大小对线粒体进化的不同速率相对不敏感，但我们在这里表明，速率不对称可以对生存不对称的方向产生很大影响。在物种间的正反交中，线粒体进化较快的母本由于有丝分裂核不相容的可能性增加，往往会产生不太可行的F_1杂种。我们使用一类淡水鱼的相互杂交生存能力和分子进化速率的数据来检验这一预测。正如预测的那样，线粒体进化加速的物种往往是F_1杂种的母本更差，这为达尔文的推论提供了系统基础的第一个比较证据。这一结果与有丝分裂核不相容在生殖隔离中发挥重要作用的假设是一致的。这种不对称的生殖隔离可能有助于解释在许多杂交物种之间观察到的不对称线粒体内移。然而，与任何比较研究一样，我们不能排除我们的结果与第三个变量(如体型)相互关联的可能性。
Reciprocal crosses between species can yield hybrids with different viabilities. The high frequency of this asymmetric hybrid viability ("Darwin's corollary") places it alongside Haldane's rule and the "large-X effect" as a general feature of postmating reproductive isolation. Recent theory suggests that reciprocal cross asymmetries can arise from stochastic substitutions in uniparentally inherited loci such as mitochondrial genomes, although large systematic differences in mitochondrial substitution rates can also contribute to asymmetries. Although the magnitude of asymmetry will be relatively insensitive to unequal rates of mitochondrial evolution in diverging species, we show here that rate asymmetries can have a large effect on the direction of viability asymmetries. In reciprocal crosses between species, the maternal parent with faster mitochondrial evolution will tend to produce less viable F, hybrids owing to an increased probability of mito-nuclear incompatibilities. We test this prediction using data on reciprocal hybrid viability and molecular evolution rates from a clade of freshwater fishes, Centrarchidae. As predicted, species with accelerated mitochondrial evolution tend to be the worse maternal parent for F, hybrids, providing the first comparative evidence for a systematic basis to Darwin's corollary. This result is consistent with the hypothesis that mito-nuclear incompatibilities can play an important role in reproductive isolation. Such asymmetrical reproductive isolation may help explain the asymmetrical mitochondrial introgression observed between many hybridizing species. However, as with any comparative study, we cannot rule out the possibility that our results arise from a mutual correlation with a third variable such as body size.