Marine threespine sticklebacks haven't morphologically changed in an estimated 10 million years, but their freshwater offshoots show no signs of slowing down. These 5-cm-long, freshwater fish have undergone a recent evolutionary change, variably losing their calcified body armor and retractable pelvic and dorsal spines. Remarkably, isolated marine and freshwater sticklebacks can be hybridized in the laboratory, a fact that is allowing researchers to analyze the genetics behind their natural diversification.
"Despite all of the interest in how evolution really works, and despite all we know about the genetic pathways that build tissues, we have surprisingly few real examples where traits in natural populations are understood at the molecular level," says David Kingsley, a recent convert to stickleback research at Stanford University. Kingsley and colleagues have made the link, finding that a single gene might control pelvic armor loss in freshwater sticklebacks.
It's a finding that goes against a longstanding belief ...
