A team led by biologists at The University of Texas at Arlington has published a study that supports the theory that species that reproduce asexually have more harmful genetics.
The lead author of the paper is a PhD student at UTA. It was published in Evolution in May.
The co-authors are T.J. Firneno, Alexander Hall and Matt.
Parthenogenesis is a form of asexual reproduction that does not involve fertilization by sperm. Sexual reproduction is thought to lead to less harmful genetic changes than asexual reproduction.
Maldonado and his co-authors studied the Aspidoscelis, a group of whiptail lizards. The reptiles are an excellent model system for studying the cellular mechanisms of parthenogenesis and the consequences of asexuality due to their high abundance and distribution throughout the southwestern United States and northern Mexico.
The team used wholeMitochondrial genome data from asexual and sexual whiptail lizards to investigate their prediction.
The study shows that when whiptail lizards transition from reproducing sexually to asexually, they accumulate harmful genes in the mitochondria. Sex is the dominant form of reproduction in the natural world due to the fact that asexuals accumulate more harmful genes than their sexual counterparts.
The team obtained additional tissue samples from collections at the Burke Museum of Natural History and Culture in Seattle and the American Museum of Natural History in New York City.
Their research shows that the transition to asexuality led to relaxed natural selection in parthenogenetic lizards and the build up of non-synonymous mutations. They wrote that the loss of sex should lead to an irreversible build-up of deleterious genes due to a reduction in the efficiency of selection.
According to Firneno, the main finding of the study is that asexual lizards have higher rates of amino acid substitution than sexual lizards. It is important because the pervading form of reproduction is more expensive than the sexually reproducing one.
More information: Jose A. Maldonado et al, Parthenogenesis doubles the rate of amino acid substitution in whiptail mitochondria, Evolution (2022). DOI: 10.1111/evo.14509 Journal information: Evolution
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