Section of Integrative Biology, University of Texas, Austin.
Mol Biol Evol. 2013 Oct;30(10):2302-10. doi: 10.1093/molbev/mst127. Epub 2013 Jul 27.
Genetic incompatibilities are commonly observed between hybridizing species. Although this type of isolating mechanism has received considerable attention, we have few examples describing how genetic incompatibilities evolve. We investigated the evolution of two loci involved in a classic example of a Bateson-Dobzhansky-Muller (BDM) incompatibility in Xiphophorus, a genus of freshwater fishes from northern Central America. Hybrids develop a lethal melanoma due to the interaction of two loci, an oncogene and its repressor. We cloned and sequenced the putative repressor locus in 25 Xiphophorus species and an outgroup species, and determined the status of the oncogene in those species from the literature. Using phylogenetic analyses, we find evidence that a repeat region in the proximal promoter of the repressor is coevolving with the oncogene. The data support a hypothesis that departs from the standard BDM model: it appears the alleles that cause the incompatibilities have coevolved simultaneously within lineages, rather than in allopatric or temporal isolation.
遗传不相容性在杂交物种中很常见。尽管这种隔离机制受到了相当多的关注，但我们很少有例子描述遗传不相容性是如何进化的。我们研究了两个位点的进化，这两个位点涉及到北中美淡水鱼类属 Xiphophorus 中的一个 Bateson-Dobzhansky-Muller (BDM) 不相容性的经典例子。由于两个基因座的相互作用，杂种会产生致命的黑色素瘤，一个是致癌基因，另一个是其抑制剂。我们克隆并测序了 25 种 Xiphophorus 物种和一个外群物种的假定抑制剂基因座，并从文献中确定了这些物种中致癌基因的状态。通过系统发育分析，我们发现证据表明抑制剂近端启动子中的重复区域与致癌基因共同进化。这些数据支持了一个偏离标准 BDM 模型的假设：似乎导致不相容性的等位基因在种系内同时进化，而不是在异地或时间隔离中进化。
