LeVasseur-Viens Hélène, Moehring Amanda J
Department of Biology, Western University, BGS 2080, 1151 Richmond Street, London, ON, Canada N6A 5B7.
Int J Evol Biol. 2014;2014:808247. doi: 10.1155/2014/808247. Epub 2014 Sep 8.
External genitalia are one of the most rapidly evolving morphological features in insects. In the Drosophila melanogaster species subgroup, males possess a nonfertilizing external genital structure, called the posterior lobe, which is highly divergent among even closely related species. A previous study on this subgroup mapped two genomic regions that affect lobe size and four that affect lobe shape differences between D. mauritiana and D. sechellia; none of the regions affected both size and shape. Here, we investigate whether three of these significant regions also affect lobe size and shape differences between the overlapping species pair D. mauritiana and D. simulans. We found that the same three regions of D. mauritiana, previously shown to affect lobe morphology in a D. sechellia genetic background, also affect lobe morphology in a D. simulans genetic background, with one of the regions affecting both size and shape. Two of the regions also affected morphology when introgressed in the reciprocal direction. The overlap of regions affecting genital morphology within related species pairs indicates either that there is a common underlying genetic basis for variation in genital morphology within this species group or that there are multiple adjacent loci with the potential to influence genital morphology.
外生殖器是昆虫中进化最为迅速的形态特征之一。在黑腹果蝇物种亚组中，雄性拥有一种无受精功能的外生殖器结构，称为后叶，即使在亲缘关系很近的物种之间，后叶也存在很大差异。此前针对该亚组的一项研究绘制了两个影响叶大小的基因组区域和四个影响毛里求斯果蝇和塞舌尔果蝇之间叶形状差异的基因组区域；没有一个区域同时影响大小和形状。在这里，我们研究这三个重要区域是否也影响重叠物种对毛里求斯果蝇和拟果蝇之间的叶大小和形状差异。我们发现，毛里求斯果蝇的相同三个区域，先前显示在塞舌尔果蝇的遗传背景中影响叶形态，在拟果蝇的遗传背景中也影响叶形态，其中一个区域同时影响大小和形状。当以相反方向导入时，其中两个区域也影响形态。相关物种对中影响生殖器形态的区域重叠表明，要么在这个物种组内生殖器形态变异存在共同的潜在遗传基础，要么存在多个有潜力影响生殖器形态的相邻基因座。
