April 12 (UPI) — It’s not new genetic coding, but how genes are regulated and expressed, that enables new adaptions, which are the physiological experiments that enable evolution and spawn new species.
Researchers at the Santa Fe Institute believe they’ve identified the kind of gene regulation most likely to produce evolutionary change.
Most living organisms store their genetic coding in DNA form and use so-called protein transcription factors to control the transcription of DNA into RNA. Transcription factors bind with DNA sequences and act as either an enhancer or repressor, encouraging or blocking the transcription of genetic information from DNA to messenger RNA.
According to the latest research, this type of gene regulation — at the DNA level, via transcription factors — is more likely than regulation at the RNA level to yield evolutionary adaptations. Researchers described their discovery this week in the journal PNAS.
“That really surprised us,” Andreas Wagner, an evolutionary biologist and external professor at the Santa Fe Institute, said in a news release. “It’s not self-evident. It’s one of those things you just don’t know before you look.”
“New forms of regulation are crucial for a lot of new features of life,” Wagner said. “What distinguishes the body plan of humans from that of sea urchins or fruit flies is new kinds of regulation — turning the right genes on and off at the right time.”
Wagner and his colleagues identified a correlation between transcription factors and two vital evolutionary traits, robustness and evolvability. Robustness describes a system’s ability to function despite mutations, while evolvability refers to a system’s ability to generate new traits as a result of new mutations.
“We find that transcription factor binding sites are highly evolvable because mutations often create binding sites for other transcription factors,” said Joshua Payne, researcher at ETH Zurich. “In this way, mutations to transcription factor binding sites can readily bring forth phenotypic variation.”
Researchers surmise the improved evolvability offered by the use of transcriptional regulation likely explains why most living organisms abandoned the use of RNA for genetic storage some 4 billion years ago — opting for DNA and proteins, instead.