Junk DNA goodbye!: neutral DNA is shown as smaller (Introduction)

by David Turell , Friday, October 26, 2018, 22:44 (2220 days ago) @ David Turell
edited by David Turell, Friday, October 26, 2018, 23:08

The neutral DNA theory is now questioned:

https://www.sciencedaily.com/releases/2018/10/181010105536.htm

"Researchers recently discovered that 95 percent of our genome seems to be affected by selection and other genetic biases and that markers previously thought to be neutral appear to provide skewed estimates. Their study calls for the re-examination of a plethora of results and provides the tools and recommendations to correct such issues in the future.

"Geneticists use standards to reconstruct the history of a species or to evaluate the impact of mutations, in the form of genetic markers scattered throughout the genome. Provided these markers are neutral, i.e. that they have evolved randomly rather than through a selective process, they can be reliably used as "standards" to compare various parameters across populations.

"However, what scientist Fanny Pouyet and colleagues from the Group of Laurent Excoffier at the SIB Swiss Institute of Bioinformatics and University of Bern recently discovered, is that 95% of our genome actually seems to be affected by selection and other genetic biases and that markers previously thought to be neutral appear to provide skewed estimates. Their study, published in eLife, calls for the re-examination of a plethora of results and provides the tools and recommendations to correct such issues in the future.

***

"'What we find is that less than 5% of the human genome can actually be considered as "neutral"," says Fanny Pouyet, lead author of the study. "This is a striking finding: it means that 95% of the genome is indirectly influenced by functional sites, which themselves represent only 10% to 15% of the genome," she concludes. These functional sites encompass both genes and regions involved in gene regulation.

***

"'We re-examined all existing sets of markers presented as "neutral" and found that they provided, under one aspect or another, skewed estimates" indicates Pouyet. The team then went on to identify a new set of markers that matched, this time, all the neutrality criteria, using two whole genome datasets of over a hundred individuals in total. This neutral dataset has now been made available for humans, but the method could in theory be used to find such markers in any other species."

Comment: What this indicates is most of DNA is actively involved, and it not just limited to coding, as originally thought, and gene regulation is DNA-wide function. Not much is junk. From the original study is this comment:

"Pouyet, Aeschbacher et al. created a measure of genetic diversity that is only affected by selection or transmission bias. The results showed that negative selection influences as much as 85 percent of our genome, whereas transmission bias affects a majority of the rest of the genome. After removing these two biases, less than 5 percent of the human genome is found to evolve by chance. This suggests that while most of our genetic material is formed of non-functional sequences, the vast majority of it evolves indirectly under some type of selection."

https://elifesciences.org/articles/36317

And who or what is doing the selecting?