source (h/t Complexity Digest)
Scientists Find Vital Genes Evolving in Genome’s Junkyard | Quanta Magazine

Scientists Find Vital Genes Evolving in Genome’s Junkyard

Even genes essential for life can be caught in an evolutionary arms race that forces them to change or be replaced.3

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Colorized micrograph of a cell’s nucleus, showing euchromatin and heterochromatin. — Inside the nucleus of a cell, most of the active genes are in the portion of the DNA called euchromatin (magenta). The more condensed DNA of the heterochromatin (black) is mostly genetically inert, but researchers are learning how new genes can evolve there.Dr. Gopal Murti / Science Source

November 16, 2020

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Essential genes are often thought to be frozen in evolutionary time — evolving only very slowly if at all, because changing or dying would lead to the death of the organism. Hundreds of millions of years of evolution separate insects and mammals, but experiments show that the Hox genes guiding the development of the body plans in Drosophila fruit flies and mice can be swapped without a hitch because they are so similar. This remarkable evolutionary conservation is a foundational concept in genome research.

But a new study turns this rationale for genetic conservation on its head. Researchers at the Fred Hutchinson Cancer Research Center in Seattle reported last week in eLife that a large class of genes in fruit flies are both essential for survival and evolving extremely rapidly. In fact, the scientists’ analysis suggests that the genes’ ability to keep changing is the key to their essential nature. “Not only is this questioning the dogma, it is blowing the dogma out of the water,” said Harmit Malik, a Howard Hughes Medical Institute investigator who oversaw the study.

“This work is so beautiful,” said Manyuan Long, an evolutionary geneticist at the University of Chicago. “The researchers found that rapidly changing heterochromatin drives the evolution of new essential genes. Just amazing!”