Shapiro redux: bacterial resistance (Introduction)

by David Turell , Tuesday, November 28, 2023, 19:14 (151 days ago) @ David Turell

New math approach:

https://www.quantamagazine.org/evolving-bacteria-can-evade-barriers-to-peak-fitness-202...

"Over the course of the last hundred years, evolutionary biologists have used mathematical models and, increasingly, lab experiments with living organisms to explore how populations of all sizes can move through fitness landscapes (sometimes called adaptive landscapes). Now, in a study just published in Science, researchers have engineered more than a quarter-million versions of a common bacterium and plotted each strain’s performance to create one of the largest lab-built adaptive landscapes ever. It enabled them to ask: How hard is it to get from any given point to the peaks?

***

"As huge as the fitness landscape in Wagner’s new paper is, it shows only what the bacteria are capable of in a single specific environment. If the researchers changed any of the particulars — if they changed the dose of the antibiotic or raised the temperature, say — they would get a different landscape. So although the findings seem to suggest that most E. coli strains can evolve antibiotic resistance, that outcome might be either far less likely or far more likely in the real world. All that seems certain is that most strains probably aren’t irrevocably sabotaged by their own minor successes.

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"Wagner and Papkou are hoping to explore other versions of the landscape in future work. Papkou notes that it is not possible to map every permutation of even a single gene comprehensively — the landscape would explode to astronomical size almost immediately. But with lab-built landscapes and theoretical models, it should still be possible today to begin exploring whether universal principles undergird how an evolving entity can change in response to its environment.

“'The bottom line is: It is pretty easy for Darwinian evolution to start in a suboptimal position and move by force of natural selection to a high fitness peak,” Papkou said. “It was pretty astonishing.'”

Comment: Shapiro all over again. Bacteria have a definite way to protect themselves by editing DNA. Why? They started life and have stayed around to contribute positively to so many aspects of life like our gut microbiome.