DNA fragility in the parallel evolution of pelvic reduction in stickleback fish

DNA breakage and adaptation Adaptation to new environments often occurs in similar ways across different colonization events. Stickleback fish represent a classic example of this, in which repeated colonizations of freshwater have resulted in the loss of pelvic hind fins. Previous work has shown that a pelvic enhancer gene is involved. Xie et al. now show that this gene lies within a region of the genome that is prone to double-stranded DNA breakage owing to a high thymine-guanine content. This enhanced region of breakage could lead to enhanced mutation rates that facilitate repeated adaptations to new environments. Science , this issue p. 81