Creationists are forever claiming that new genetic features cannot occur naturally and must be the result of magical design (see Discovery Institute: No Evidence for Evolution).
At the news bureau of the University of Illinois there’s a story about some research the creationists have been hoping would never be done. Here are some excerpts from Researchers show how one gene becomes two (with different functions), The bold font was added by us:
Researchers report that they are the first to show in molecular detail how one gene evolved two competing functions that eventually split up – via gene duplication – to pursue their separate destinies.
Shrieking and wailing can be heard at a certain “think tank” in Seattle. Let’s read on:
The study, in the Proceedings of the National Academy of Sciences, validates a decades-old hypothesis about a key mechanism of evolution. The study also confirms the ancestry of a family of “antifreeze proteins” that helps the Antarctic eelpout survive in the frigid waters of the Southern Ocean.
Here’s a link to the abstract: Evolution of an antifreeze protein by neofunctionalization under escape from adaptive conflict. We continue with the news release:
“I’m always asking the question of where these antifreeze proteins come from,” said University of Illinois animal biology professor Christina Cheng, who has spent three decades studying the genetic adaptations that enable Antarctic fish to survive in one of the coldest zones on the planet. “The cell usually does not create new proteins from scratch.”
This is Christina Cheng’s page at the university’s website. Here’s more:
Scientists have known since 2001 that the sequence of genes coding for a family of antifreeze proteins (known as AFP III) was very similar to part of a sequence of a gene that codes for a cellular enzyme in humans. Since Antarctic fish also produce this enzyme, sialic acid synthase (SAS), it was thought that the genes for these antifreeze proteins had somehow evolved from a duplicate copy of the SAS gene. But no study had shown how this happened with solid experimental data.
And the fact that this kind of evolution hadn’t yet been shown to happen gave comfort to creationists. (Besides that, one can hear them saying: “I ain’t no kin to no Antarctic fish.”) Moving along:
[Skipping some details …] Further analysis revealed that the SAS proteins function as enzymes but also have modest ice-binding capabilities. This finding supports a decades-old hypothesis that states that when a single gene begins to develop more than one function, duplication of that gene could result in the divergent evolution of the original gene and its duplicate.
The new finding also supports the proposed mechanism, called “escape from adaptive conflict,” by which this can occur. According to this idea, if a gene has more than one function, mutations or other changes to the gene through natural selection that enhance one function may undermine its other function.
“The original enzyme function and the emerging ice-binding function of the ancestral SAS molecule might conflict with each other,” Cheng said. When the SAS-B gene became duplicated as a result of a copying error or some other random event in the cell, she said, then each of the duplicate genes was freed from the conflict and “could go on its own evolutionary path.”
This is rather technical. One more excerpt:
Later, after the SAS gene was duplicated and the AFP gene went on its own evolutionary path, Cheng said, the antifreeze protein appears to have evolved into a secreted protein, allowing it to disrupt ice formation in the bloodstream and extracellular fluid, where it would be of most benefit to the adult fish.
Perhaps this excerpt from the abstract of the published paper explains it better:
We report here clear experimental evidence for EAC-driven evolution of type III antifreeze protein gene from an old sialic acid synthase (SAS) gene in an Antarctic zoarcid fish. We found that an SAS gene, having both sialic acid synthase and rudimentary ice-binding activities, became duplicated. … This study reveals how minor functionalities in an old gene can be transformed into a distinct survival protein and provides insights into how gene duplicates facing presumed identical selection and mutation pressures at birth could take divergent evolutionary paths.
This is an actual study of the evolution of a whole new function. The creationists aren’t going to like this at all. We look forward to their reactions.
See also: New ‘Information’ from Gene Duplication.
Copyright © 2011. The Sensuous Curmudgeon. All rights reserved.