Barmina Olga, Kopp Artyom
Section of Evolution and Ecology, University of California-Davis, One Shields Ave., Davis, CA 95616, USA.
Dev Biol. 2007 Nov 15;311(2):277-86. doi: 10.1016/j.ydbio.2007.07.030. Epub 2007 Aug 1.
Animal diversity is shaped by the origin and diversification of new morphological structures. Many examples of evolutionary innovations are provided by male-specific traits involved in mating and sexual selection. The origin of new sex-specific characters requires the evolution of new regulatory interactions between sex-determining genes and genes that control spatial patterning and cell differentiation. Here, we show that sex-specific regulation of the HOX gene Sex combs reduced (Scr) is associated with the origin and evolution of the Drosophila sex comb - a novel and rapidly diversifying male-specific organ. In species that primitively lack sex combs, Scr expression shows little spatial modulation, whereas in species that have sex combs, Scr is upregulated in the presumptive sex comb region and is frequently sexually dimorphic. Phylogenetic analysis shows that sex-specific regulation of Scr has been gained and lost multiple times in Drosophila evolution and correlates with convergent origin of similar sex comb morphologies in several independent lineages. Some of these transitions occurred on microevolutionary timescales, indicating that HOX gene expression can evolve with surprising ease. This is the first example of a sex-specific regulation of a HOX gene contributing to the development and evolution of a secondary sexual trait.
动物多样性是由新形态结构的起源和多样化塑造的。许多进化创新的例子都由参与交配和性选择的雄性特异性性状提供。新的性别特异性特征的起源需要性别决定基因与控制空间模式和细胞分化的基因之间新的调控相互作用的进化。在这里，我们表明HOX基因性梳减少（Scr）的性别特异性调控与果蝇性梳的起源和进化相关——性梳是一种新颖且快速多样化的雄性特异性器官。在原始缺乏性梳的物种中，Scr表达几乎没有空间调节，而在具有性梳的物种中，Scr在假定的性梳区域上调，并且经常表现出性别二态性。系统发育分析表明，Scr的性别特异性调控在果蝇进化过程中多次获得和丧失，并与几个独立谱系中相似性梳形态的趋同起源相关。其中一些转变发生在微观进化时间尺度上，表明HOX基因表达可以非常容易地进化。这是HOX基因的性别特异性调控促进次要性征发育和进化的第一个例子。
