Morphological evolution caused by many subtle-effect substitutions in regulatory DNA
Nicolás Frankel,1, 4 Deniz F. Erezyilmaz,1, 4 Alistair P. McGregor,2 Shu Wang,1 Fran?ois Payre3 & David L. Stern1
Affiliations Contributions Corresponding author Journal name:
Nature Volume: 474,
Pages: 598–603 Date published: (30 June 2011)
DOI:
doi:10.1038/nature10200
Received 04 February 2011 Accepted 13 May 2011 Published online 29 June 2011
Abstract
Abstract Author information Supplementary information Comments Article tools

Share/bookmarkConnotea Cite U Like Facebook Twitter Delicious Digg Morphology evolves often through changes in developmental genes, but the causal mutations, and their effects, remain largely unknown. The evolution of naked cuticle on larvae of Drosophila sechellia resulted from changes in five transcriptional enhancers of shavenbaby (svb), a transcript of the ovo locus that encodes a transcription factor that governs morphogenesis of microtrichiae, hereafter called ‘trichomes’. Here we show that the function of one of these enhancers evolved through multiple single-nucleotide substitutions that altered both the timing and level of svb expression. The consequences of these nucleotide substitutions on larval morphology were quantified with a novel functional assay. We found that each substitution had a relatively small phenotypic effect, and that many nucleotide changes account for this large morphological difference. In addition, we observed that the substitutions had non-additive effects. These data provide unprecedented resolution of the phenotypic effects of substitutions and show how individual nucleotide changes in a transcriptional enhancer have caused morphological evolution.

Subject terms:Evolution Genetics and genomics Developmental biology Molecular biology

Top of page渐进性的演化改变
Nature 474 (30 Jun 2011)

形态演化经常涉及发育基因的变化，但造成这些演化的突变的数量和效应在很大程度上却仍不知道。Frankel等人利用果蝇的shavenbaby基因作为一个模型系统，来研究这一现象的遗传学。他们发现，shavenbaby基因的5个顺位调控增强子之一所发生的演化变化来自很多核苷酸替代，这些替代既改变了该基因表达的时机，又改变了其水平。因此，这种果蝇要形成一种无毛的幼虫，将需要很多有较小影响的突变（而不是一个有较大影响的突变）。这项工作在单核苷酸替代水平上为达尔文所赞同的关于存在一个渐进性演化过程的观点提供了定量支持。