Adaptive evolution of pelvic reduction in sticklebacks by recurrent deletion of a Pitx1 enhancer.
Chan YF, Marks ME, Jones FC, Villarreal G Jr, Shapiro MD, Brady SD, Southwick AM, Absher DM, Grimwood J, Schmutz J, Myers RM, Petrov D, Jónsson B, Schluter D, Bell MA, Kingsley DM.
Science. 2010 Jan 15;327(5963):302-5.
This paper is most recent in a series of papers over the past decade in which the Kingsley Lab has used stickleback fish as a model to investigated the genetic bases of adaptive natural variation. Marine populations of stickleback have a pelvic apparatus that consists of articulating spines along the fishes lateral sides. Interestingly, several independently derived freshwater populations have lost this structure. Previous work had determined that a chromosome region containing the Pitx1 gene was responsible for pelvic structure loss in multiple populations, and that Pitx1 expression is lost in pelvic reduced stickleback. These and other data suggested that cis-regulatory mutations at the Pitx1 locus were responsible for pelvic reduction. However, regulatory mutations are difficult to identify and the exact sequence changes controlling pelvic reduction had not been identified. In this paper, the authors identify the exact genetic changes responsible for this loss in multiple populations.