Evolutionary biology, a field predominantly focused on understanding the diverse array of life, is now challenging conventional wisdom with groundbreaking research suggesting that natural selection, often associated with driving change, can also play a crucial role in preserving similarities between populations.
Lead author and evolutionary biologist, Jeff Conner, from Michigan State University, and a team of researchers from the United States and China, delved into the intricacies of natural selection by studying wild radish (Raphanus raphanistrum). Their findings, published in the New Phytologist, provide novel insights into the mechanisms behind the preservation of specific traits over extensive periods.
While natural selection is conventionally regarded as the driving force behind the vast diversity of life, the study suggests it can also act as a stabilizing influence, maintaining certain characteristics within a species. The research focused on ‘anther separation,’ a trait in wild radishes where the lengths of pollen-producing organs vary.
Conner explains, “Our work flips the script on that a little bit. We’re suggesting that selection can also slow things down, that it can cause similarities as well as differences.”
The team aimed to investigate whether constraint, a phenomenon inhibiting the evolution of traits, could be responsible for maintaining anther separation in wild radishes. Through artificial selection, they bred the plants to revert to a more primitive state with a smaller gap between stamens.
“If a trait responds to artificial selection, it clearly can evolve,” the authors note in their paper. “But if the trait does not respond, there is a constraint caused by a lack of genetic variation.”
The study involved six generations and 3,437 wild radish plants, revealing that the researchers could significantly reduce the difference in stamen lengths through artificial selection. This indicates that the current generation of wild radishes possesses the genetic variation needed for evolution, suggesting that natural selection, rather than constraint, is responsible for maintaining the observed trait.
Conner emphasizes the significance of the findings, stating, “This family of plants has maintained this four-long, two-short trait over 50 million years, and we can get rid of a third of the difference in five generations.”
The researchers are now conducting experiments to determine whether the varying lengths of stamens provide any benefits to wild radishes in terms of their interactions with pollinators. Conner concludes, “Natural selection is very important. A lot of things people have thought selection couldn’t do, we’re learning selection can do.” This research challenges our understanding of evolution and highlights the intricate balance between change and preservation in the natural world.
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