A study of fishing practices and whitefish characteristics in Canada’s Lesser Slave Lake has revealed an interesting case of natural selection (or possibly artificial selection since man is the cause). in action. University of Calgary evolutionary biologist Sean Rogers plans to investigate changes in the genetic composition of the whitefish population at the lake—which appears to have come about as a result of human fishing.
Smaller whitefish have a reproductive advantage.
Because fishermen use nets designed to catch the biggest fish, smaller whitefish have a reproductive advantage—they are captured less frequently and therefore have a greater opportunity to reproduce and propagate their genes. “Instead of the bigger and best surviving, those were the ones we were actually removing from the population and consequently we elicited this selection response in the fish population,” explained Rogers.
In fact, the whitefish example is a great illustration of the workings of natural selection, an idea Charles Darwin both adopted for his evolutionary idea and expounded upon. However, Rogers points out that people often assume “survival of the fittest” means that the biggest and strongest survive. While that may often be the case, the whitefish example shows the opposite process in effect. Rogers also discussed a similar study from last year (which we covered last January) that showed other cases of “reverse evolution” (i.e., animals whose average size has dropped because of human predation).
What none of these examples demonstrate, however, is anything remotely similar to Darwin’s molecules-to-man story for life’s complexity and diversity. Darwin’s story requires the addition of new genetic information into a population, which natural selection preserves. But in this case and all other examples of “evolution in action,” genetic information is either constant or it decreases as natural selection removes certain members from the population. So such cases really are “reverse evolution”—they are the opposite of what drives Darwinian evolution.
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