Sexual competition between men is important to maintaining genetically healthy populations. A new study by Uppsala University describes how sexual selection eliminates bad mutations and helps pass genes to offspring who tend to improve their fitness.
“When harmful mutations are removed from a population through rigorous selection in males, which results in fewer males reproducing, the process can proceed with little or no impact on population growth.”
“This is because relatively few males are enough to fertilize all females in a population. Hence, it makes little or no difference whether these females are fertilized by a few males or many males, for the number of offspring these females can produce, especially in species where the male does not care for its own offspring, ”explains Head of studies Karl Grieshop, evolutionary biologist at the University of Toronto.
“In contrast, such rigorous selection in females would result in fewer females reproducing and thus producing fewer offspring, which could lead to a massive decline in the population or even to extinction.”
The researchers analyzed 16 genetic strains of seed beetles to examine how the number of harmful mutations in each affected their reproductive capacity.
The experts quantified the cumulative effects of each variety’s unique mutations from intensive inbreeding of varieties followed by crosses between them. This showed that the mutations harm both women and men almost equally.
However, when the team only looked at the crosses between the strains, which is all the more how the selection would work in nature, the mutational effects only affected male fitness. In the females, the harmful effects of the mutations they carried were undetectable against this genetically more variable background.
“This suggests that these mutations, while adversely affecting reproduction in females, are more effectively removed from the population through selection that affects male carriers than female carriers,” said Grieshop.
“Previous research by our group and others has managed to show this effect by artificially inducing mutations, but this is the first direct evidence that it occurs for naturally occurring variants of genes.”
According to the researchers, their study sheds new light on the old question of why so many multicellular organisms use sexual reproduction.
“The production of males leads to a decrease in the reproductive capacity of a species, since the males themselves contribute less than the females to the production of offspring. So the question is, why does a species evolve to reproduce sexually rather than just producing females through asexual reproduction, ”said David Berger, co-author of the study.
“Our study shows that producing males, who can compete intensely for the chance of mating, enables harmful mutations to be eliminated more quickly from the population, resulting in a healthier set of genes and higher reproductive capabilities compared to asexual reproduction could make possible. “
The study is published in the journal Evolution letters.
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By Chrissy Küster, Earth.com Employed author
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