Evolution: is it predictable? (Introduction)

by David Turell , Tuesday, January 30, 2024, 18:44 (297 days ago) @ David Turell

In the short term:

https://phys.org/news/2024-01-evolution-bacterial.html

"...if we could "rewind" the tape of life and let it run again. Would the major phylogenetic groups re-emerge, or would something entirely different happen?

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"The research sheds light on this classic question by analyzing the evolutionary behavior of experimental populations of bacteria and leveraging the analytical capabilities provided by large-scale, cutting-edge genetic tools. The results reveal that the evolution of bacteria can be predictable in the short term, opening doors to efforts to anticipate the evolution of pathogens and pests, as well as potential biotechnological applications for their control.

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"To deploy this ambitious study, researchers employed recent massive genetic engineering technology that allows the introduction of hundreds of thousands of mutations into bacteria, studying the individual effect of each one individually. "This technology allows exploring the effect, whether good or bad, of all possible mutations along the >4,000 genes of the bacterial genome," adds Couce.

"In their work, researchers applied these techniques to the ancestor and different evolutionary stages of the famous Long-Term Evolution Experiment, which has been evolving 12 populations of the same bacteria under constant laboratory conditions for more than 35 years. In total, these populations founded from the same ancestor have experienced >70,000 generations, approximately five times more than Homo sapiens have lived on Earth.

"The first significant surprise of this new study is that the overall proportion of lethal, harmful, and neutral mutations remains virtually constant throughout the evolution of these 12 lineages, despite the specific identity of the mutations showing great volatility. (my bold)

"For researchers, a case of particular relevance is lethal mutations: Mutations that, as the name implies, lead to the death of the organism, revealing which genes and systems are essential for life. The results show that many lethal genes in the ancestor cease to be lethal in evolved strains, but a similar fraction of non-lethal mutations in the ancestor becomes lethal later. The result, as Couce explains, is that "the fraction of lethal mutations has enigmatically remained constant during evolution." (my bold)

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"'We started with an almost philosophical approach: if we could know all possible beneficial mutations for an organism at a given time, could we predict adaptation?" says the UPM researcher. "It can be seen as a biological version of Laplace's Demon, the thought experiment in which the famous French physicist wondered if for a superhuman intelligence capable of knowing the position and movement of every atom in the universe, it would not be trivial to reconstruct the past and predict the future."

"'Our results show that major initial adaptations are predictable, and as evolution progresses, this ability is lost," he explains. "In other words, the demon exists but is terribly shortsighted.'"

Comment. Since major evolutionary advances have stopped, their conclusions fit that current statis. The need for immediate adaptation is usually obvious within species. So, if we are not seeing new speciation, how can we learn how to predict? My bolds about lethal mutations fits into our discussion about 99.9% of all ancestors are lost to produce 0.1% surviving.