One million years without sex fails to erase stick insects' unused biological system
Scientists have made a surprising finding about how an asexually reproducing stick insect has evolved. Research led by Dr. Darren Parker, lecturer in evolutionary biology at Bangor University, studied the genes of several species of Timema (a type of stick insect), which have not engaged in sexual reproduction for 1 million years—the longest known asexual period for any insect.
Scientists have discovered that an asexually reproducing stick insect species, which has not engaged in sexual reproduction for 1 million years, maintains fully functional dosage compensation mechanisms on its X chromosomes. Dr. Darren Parker, a lecturer in evolutionary biology at Bangor University, led the research on Timema stick insects.
Typically, males and females have different numbers of X chromosomes, necessitating a balance in gene expression through mechanisms known as dosage compensation. The study, published in PNAS, found that despite the absence of sexual reproduction, these dosage compensation mechanisms remained fully operational. The researchers expected the mechanisms to decay over time, as they are no longer needed.
However, their findings challenge the assumption that biological systems rapidly decay when they are no longer under strong evolutionary pressure. This discovery highlights that evolution does not always discard what is no longer needed.
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