An article in the current issue of Current Biology describes a fascinating experiment with profound results. Like the best science, the experiment is simple and elegant. Researchers took blind cave fish from two different cave systems and mated them. The offspring had fully functional eyes. It turns out that different parts of the developmental system had broken down in the eye-producing mechanisms of these two different fish populations. In essence, they represented two different evolutionary trajectories. Technically, a certain spot in the genes for making one part of the eye mutated in one population of cave fish, and another spot (or "locus") mutated in a second population. The fish were both blind, but they were blind for different reasons. What was wrong with one was right with the other, and by breeding them good genes cancelled out bad, at least in some of the offspring. The remarkable implication is that researchers produced sighted fish from two populations that hadn't seen in over a million years! It's a powerful confirmation of their independent origins in different cave systems -- basically a subterranean example of how evolution takes populations of organisms in different directions based on their own individual circumstances and histories.

A summary of the work is found at National Geographic's website, for those of you who don't subscribe to Current Biology.

Labels: caves, evolution