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Strength in weakness: Fragile DNA regions key to vertebrate evolution

DNA regions susceptible to breakage and loss are genetic hot spots for important evolutionary changes, according to Stanford study. The findings may lead to new understanding of human evolution.

Regions of DNA susceptible to deletion during replication may have allowed vertebrates to successfully adapt to rapidly changing environmental conditions during evolution, according to a study by researchers at the Stanford University School of Medicine

The research suggests that some critical evolutionary changes are likely to have occurred in leaps and bounds through the abrupt loss of stretches of DNA, rather than through the slow accumulation and additive effects of many small mutations. 

The researchers, who studied a tiny fish called the threespine stickleback, found that such “fragile” DNA regions create genetic hot spots that mutate much more rapidly, and dramatically, than neighboring sequences. The resulting changes can help an organism vault far ahead of its peers in the evolutionary arms race. 

Although similar findings have been described in bacteria, this is one of the first studies to show that the same process has occurred in vertebrates to create dramatic changes in body structure. It also addresses a long-standing mystery in evolutionary biology.

“There is a lot of evidence that the same genes across different populations or species are often responsible for similar evolutionary changes,” said David Kingsley, PhD, professor of developmental biology. “What hasn’t been clear is why this is happening. This study describes at a biochemical level, down to the atoms and sequences in DNA, how a particular type of mutation can arise repeatedly, which then contributes to a complex skeletal trait evolving over and over again in wild fish species. It’s a great example of how DNA fragility can sometimes contribute to favorable traits rather than diseases in natural populations, and it may give us important insights into the process of human evolution.”

Kingsley, a Howard Hughes Medical Institute investigator, is the senior author of the study, which was published Jan. 4  in Science. Graduate student Kathleen Xie is the lead author of the work. 

Read the whole article in the Stanford Medicine News Center.

Autor: Krista Conger   Quelle: Stanford Medicine, Jan 3, 2019
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