Fins to Limbs: study identifies possible gene trigger

In the complex web of evolution, one of the pivotal moments occurred with the transition from aquatic animals to land animals - an event marked by the change from fins to limbs. While fossils have shown us evidence of this transition, the actually biological processes, what accomplished this change, has not been clear.

In a report recently published in Nature, a research team from the University of Ottawa conducted experiments that could shed some light on evolutionary change. Their studies identified a group of genes responsible for the supportive fibers found in fish fins, not found in tetrapods (land animals). These genes, known as actinodins, were found in both the researchers' primary laboratory specimen, the zebrafish, and in the elephant shark - an example of an ancient fish that has changed very little from its millions year old ancestors.

By chemically suppressing the actinodin genes in zebrafish embryos or in adults that were regenerating new fins, the resulting fins lacked the supporting fibers. What could not be tested is the causal event that might have triggered the gene change millions of years ago or whether the gene loss occurred as the instigator of change or as a reaction to some other evolutionary biological process.

"It's a very nice example of how changes in one or two genes can be responsible for a huge evolutionary transition," says Axel Meyer, a evolutionary biologist at the University of Konstanz. "We tend to think that new genes bring new functions, but this study shows that the presence of genes constrains or directs development in certain directions. Gene loss is actually a creative force in evolution."

Evolution is an incredibly complex process that not only provides historical insight but has the potential for unlocking secrets into the processes that impact species today in their ability to alter or adapt to changing circumstances. While some people do not subscribe to theories of evolution for religious reasons, I find that, if there is a higher power, there is no clearer evidence than in the intricacies of evolution, from single-celled organisms eons ago to the diversity of life that graces this planet today - a diversity that is being threatened by one of its most successful species.

Read more about the study in Scientific American.