Prud'homme Benjamin, Gompel Nicolas, Rokas Antonis, Kassner Victoria A, Williams Thomas M, Yeh Shu-Dan, True John R, Carroll Sean B
University of Wisconsin and Howard Hughes Medical Institute, Bock Laboratories, 1525 Linden Drive, Madison, Wisconsin 53706, USA.
Nature. 2006 Apr 20;440(7087):1050-3. doi: 10.1038/nature04597.
The independent evolution of morphological similarities is widespread. For simple traits, such as overall body colour, repeated transitions by means of mutations in the same gene may be common. However, for more complex traits, the possible genetic paths may be more numerous; the molecular mechanisms underlying their independent origins and the extent to which they are constrained to follow certain genetic paths are largely unknown. Here we show that a male wing pigmentation pattern involved in courtship display has been gained and lost multiple times in a Drosophila clade. Each of the cases we have analysed (two gains and two losses) involved regulatory changes at the pleiotropic pigmentation gene yellow. Losses involved the parallel inactivation of the same cis-regulatory element (CRE), with changes at a few nucleotides sufficient to account for the functional divergence of one element between two sibling species. Surprisingly, two independent gains of wing spots resulted from the co-option of distinct ancestral CREs. These results demonstrate how the functional diversification of the modular CREs of pleiotropic genes contributes to evolutionary novelty and the independent evolution of morphological similarities.
形态相似性的独立进化很普遍。对于简单性状，如整体体色，通过同一基因的突变进行反复转变可能很常见。然而，对于更复杂的性状，可能的遗传途径可能更多；其独立起源的分子机制以及它们在多大程度上受到某些遗传途径的限制在很大程度上尚不清楚。在这里，我们表明，参与求偶展示的雄性翅膀色素沉着模式在果蝇进化枝中多次获得和丧失。我们分析的每个案例（两次获得和两次丧失）都涉及多效色素沉着基因黄色的调控变化。丧失涉及同一顺式调控元件（CRE）的平行失活，少数核苷酸的变化足以解释两个姐妹物种之间一个元件的功能差异。令人惊讶的是，翅膀斑点的两次独立获得是由不同祖先CRE的共同选择导致的。这些结果证明了多效基因的模块化CRE的功能多样化如何促进进化新奇性和形态相似性的独立进化。
