Department of Developmental Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
Science. 2010 Jan 15;327(5963):302-5. doi: 10.1126/science.1182213. Epub 2009 Dec 10.
The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. Pelvic loss in different natural populations of threespine stickleback fish has occurred through regulatory mutations deleting a tissue-specific enhancer of the Pituitary homeobox transcription factor 1 (Pitx1) gene. The high prevalence of deletion mutations at Pitx1 may be influenced by inherent structural features of the locus. Although Pitx1 null mutations are lethal in laboratory animals, Pitx1 regulatory mutations show molecular signatures of positive selection in pelvic-reduced populations. These studies illustrate how major expression and morphological changes can arise from single mutational leaps in natural populations, producing new adaptive alleles via recurrent regulatory alterations in a key developmental control gene.
在自然界中反复出现的主要表型变化的分子机制通常是未知的。在不同的三刺鱼自然种群中，骨盆缺失是通过调控突变删除垂体同源盒转录因子 1（Pitx1）基因的组织特异性增强子而发生的。Pitx1 缺失突变的高发生率可能受到基因座固有结构特征的影响。虽然 Pitx1 缺失突变在实验室动物中是致命的，但骨盆减少的种群中 Pitx1 调控突变显示出正选择的分子特征。这些研究说明了主要的表达和形态变化如何能够从自然种群中的单一突变飞跃产生，通过关键发育控制基因的反复调控改变产生新的适应性等位基因。
