Evolution: always advancing or not? (Evolution)

by David Turell , Tuesday, February 16, 2021, 18:20 (1162 days ago) @ David Turell

Not is the current finding:

https://phys.org/news/2021-02-evolution-game-rock-paper-scissors.html

"If B is better than A, and C is better than B, it follows by the transitive property that C is better than A. And, yet, this is not always the case. Every kid is familiar with the Rock-Paper-Scissors game—the epitome of nontransitivity in which there is no clear hierarchy among the three choices, despite each two-way interaction having a clear winner: Paper beats Rock, Scissors beats Paper, and Rock beats Scissors.

"Evolution may be teeming with nontransitive interactions as well. While natural selection—the process by which organisms better adapted to their environments are more likely to survive and pass on their genes—can be observed over shorter time intervals, there is still debate about whether fitness gains accumulate over long evolutionary time scales. In other words, one might expect that successive adaptive events (like the two-way interactions of Rock-Paper-Scissors) would translate into a cumulative increase in fitness, resulting in the very latest generation always being more fit than its all of its genealogical ancestors. However, this turns out to not be true in every case.

"The evolutionary process, then, includes what are known as nontransitive interactions, sometimes producing organisms that are less fit than its ancestors. Experimental demonstrations of such nontransitivity, however, have been lacking.

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"'Another misconception is that there is a single locus of selection," says Lang. "Multilevel selection—as its name implies—states that selection can act simultaneously on multiple levels of biological organization."

In the context of this experiment, multilevel selection was common, says Lang. "Selection acts across multiple levels of biological organization, from genes within a cell to individuals within a population. Selection at one level can impact fitness at another.

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"By showing that nontransitive interactions can arise along a line of genealogical succession, the team's work has broad implications for the scientific community's understanding of evolutionary processes.

"'It resolves what evolutionary biologist Stephen Jay Gould referred to as 'the paradox of the first tier,' which is the failure to identify broad patterns of progress over long evolutionary time scales, despite clear evidence of selection acting over successive short time intervals," says Lang. "In addition, it calls into doubt whether true fitness maxima exist and, more broadly, it implies that directionality and progress in evolution may be illusory.'"

Comment: Basically evolution can go back and forth, not steadily forward