Centre for Evolution, Genes and Genomics, School of Biology, University of St. Andrews, St. Andrews, Fife, UK.
Mol Ecol. 2011 Sep;20(17):3617-30. doi: 10.1111/j.1365-294X.2011.05208.x. Epub 2011 Jul 29.
The tempo and mode of evolution of loci with a large effect on adaptation and reproductive isolation will influence the rate of evolutionary divergence and speciation. Desaturase loci are involved in key biochemical changes in long-chain fatty acids. In insects, these have been shown to influence adaptation to starvation or desiccation resistance and in some cases act as important pheromones. The desaturase gene family of Drosophila is known to have evolved by gene duplication and diversification, and at least one locus shows rapid evolution of sex-specific expression variation. Here, we examine the evolution of the gene family in species representing the Drosophila phylogeny. We find that the family includes more loci than have been previously described. Most are represented as single-copy loci, but we also find additional examples of duplications in loci which influence pheromone blends. Most loci show patterns of variation associated with purifying selection, but there are strong signatures of diversifying selection in new duplicates. In the case of a new duplicate of desat1 in the obscura group species, we show that strong selection on the coding sequence is associated with the evolution of sex-specific expression variation. It seems likely that both sexual selection and ecological adaptation have influenced the evolution of this gene family in Drosophila.
对适应和生殖隔离有较大影响的基因座的进化速度和模式将影响进化分歧和物种形成的速度。去饱和酶基因座参与长链脂肪酸的关键生化变化。在昆虫中，这些已经被证明可以影响对饥饿或抗干燥的适应，在某些情况下还可以作为重要的信息素。果蝇的去饱和酶基因家族已知是通过基因复制和多样化进化而来的，至少有一个基因座显示出性特异性表达变异的快速进化。在这里，我们研究了代表果蝇系统发育的物种中的基因家族的进化。我们发现，该家族包括的基因座比以前描述的要多。大多数都是单拷贝基因座，但我们也在影响信息素混合物的基因座中发现了其他重复的例子。大多数基因座都显示出与纯化选择相关的变异模式，但在新的重复基因座中存在强烈的多样化选择信号。在 obscura 组物种中 desat1 的一个新重复的情况下，我们表明，对编码序列的强烈选择与性特异性表达变异的进化有关。性选择和生态适应似乎都影响了果蝇中这个基因家族的进化。
