Non-genetic factors may play significant role in species evolution


An unspoken frustration for evolutionary biologists over the past 100 years, says Craig Albertson at the University of Massachusetts Amherst, is that genetics can only account for a small percentage of variation in the physical traits of organisms. Now he reports experimental results on how another factor, a “bizarre behavior” that is part of early cichlid fish larvae’s developmental environment, influences later variation in their craniofacial bones.

Albertson [and colleagues] examined a “vigorous gaping” behavior in larval fish that starts immediately after the cartilaginous lower jaw forms and before bone deposition begins.

Albertson […] says, “For over a hundred years, we’ve been taught that the ability of a system to evolve depends largely on the amount of genetic variation that exists for a trait. What is ignored, or not noted for most traits, is that less than 50 percent of genetic variation can typically be accounted for by genetics.”

The geneticist adds, “When I give talks, this is what surprises colleagues the most, that the environmental effect is on par with the genetic effect…

Sometimes longer bones are better, and one way to get there is to kick-start the bone developmental program. This gaping behavior precedes bone formation, so it may represent a way to increase efficiency by setting an animal on the trajectory toward an adaptive phenotype earlier.

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