Evolution: what works at the genetic level (Introduction)

by David Turell , Thursday, June 16, 2022, 21:01 (889 days ago) @ David Turell

Mutations or diverse gene variations?:

https://www.sciencealert.com/breeding-2000-generations-of-bacteria-may-have-solved-this...

"Having a lot of genetic options to choose from might make natural selection move a lot faster at the start, but do the genetic mutations that happen over time contribute more to species survival in the end?

***

"Each population of bacteria was engineered to have different amounts of genetic diversity at the start of the experiment.

***

"Each population was fed glucose at the start of the experiment. To test adaptability, various sets of these bacteria populations were taken and propagated in a different growth environment, providing them with the amino acid D-serine instead of glucose for their energy needs.

***

"The E. coli samples were all derived from the Long-term Experimental Evolution Project, which was started in 1988 by one of the co-authors on the recent paper, evolutionary biologist Richard Lenski.

***

"At the early stages of the experiment (around 50 generations in), the wealth of genetic diversity in the initial population was important for adaptation.

"But, by the 500th generation, the diversity at the start of the experiment "no longer mattered" because the new mutations were "sufficiently large", the authors write in their preprint, which is available on BioRxiv ahead of peer review.

"By the 500th and 2,000th generation, there were "no differences in fitness" among all the different populations of bacteria, despite the variation in fitness at the start.

"'Any benefit of pre-existing variation in asexual populations may often be short-lived, as we saw in our experiment, because that variation will be purged when new beneficial mutations sweep to fixation," the researchers write.

"While it's yet to be vetted by others in the scientific community and published in a peer-reviewed journal, this result may close the book on the longest-running argument in evolutionary biology when it comes to bacteria.

"But there is no 'right' answer in terms of the relative importance of standing variation and new mutations for adaptation in nature, the researchers write.

***

"Those studying bacteria and viruses tend to look to mutations as the major source of evolution.

"But really, both forces – mutation and existing genetic diversity – "can contribute sequentially, simultaneously, and even synergistically to the process of adaptation by natural selection", the researchers say."

Comment: Lenski's E.coli are 34 years into evolving. Using bacteria gives evolution a real broad base of individuals evolving reproduction every 20 minutes. That mutation and diversity are equallly important seems a logical finding to me. This is a pure Darwinist study with no reference to intelligent design and I present it for general interest.