Unknown Side of Natural Selection: Preservation, Not Change

When you hear the term “natural selection”, you probably think about changes, but new studies show that this mechanism can also maintain similarity between populations.

Biologists have a fairly clear understanding of the main process of evolution. The genetic diversity in the population is the result of mutations, some of which create features that help people better prosper in the current conditions. These features have good chances to be transmitted, while characteristics that are not so useful, as a rule, will not be represented in future generations. This is a natural selection.

Evolutionary biologists most often study the differences inside and between populations and species, but in life there is something more than what makes us all different.

A recent study, published in the New Phytologist magazine, revealed new aspects of natural selection that may contribute to maintaining the similarity between populations, and not just changes. Researchers from the United States and China, led by Jeff Connera from Michigan State University, studied wild radish (Raphanus raphanistrum), which in the past had all the organs producing pollen, but now have two short and four long stamens.

The study showed that the natural selection, known as the engine of evolutionary changes, can also act as a brake, preserving certain features for many generations. This phenomenon called “restriction” can occur due to a lack of genetic diversity, which complicates evolution, even if it was beneficial.

In order to check this, the team of scientists conducted experiments with artificial selection, trying to restore a more primitive state of radishes with a lower gap between the stamens. The study involved 3.437 plants grown over six generations. The results showed that the difference in stamens length decreased by more than 30%.

These findings indicate that modern wild radishes and, possibly, its related species still have the necessary genetic diversity for evolution, which makes them unlikely to limit their natural selection. Thus, the study emphasizes the importance of natural selection in maintaining the variety of living organisms.

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