Recall that ID theorist Michael Behe’s most recent book, Darwin Devolves, argued that evolution proceeds mainly by breaking or blunting genetic information if doing so confers an immediate selective advantage. Not that they
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.
Until now. A group of scientists at Lehigh University led by Gregory Lang, associate professor in the Department of Biological Sciences, has recently provided empirical evidence that evolution can be nontransitive. Lang and his team identify a nontransitive evolutionary sequence through a 1,000-generation yeast evolution experiment. In the experiment, an evolved clone outcompetes a recent ancestor but loses in direct competition with a distant ancestor.
The nontransitivity in this case arose as a result of multilevel selection that involved adaptive changes in both the yeast nuclear genome and the genome of an intracellular RNA virus. The results, which provide experimental evidence that the continuous action of selection can give rise to organisms that are less fit compared to a distant ancestor, are described in an article published in eLife Journal today called “Adaptive evolution of nontransitive fitness in yeast” (DOI: 10.7554/eLife.62238).
This study confronts two common misconceptions about evolution, according to Lang. The first, he says, is that evolution is a linear “march of progress” where each organism along a line of descent is more fit than all those that came before it…
“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.”
Lori Friedman, Lehigh University, “Evolution’s game of rock-paper-scissors” at ScienceDaily
The paper is open access.
One might ask: If things go downhill that way and “directionality and progress in evolution may be illusory,” what is the source of intelligent designs? An intelligence in or beyond nature? We’ll take either as an answer, to start a discussion.
This same week we learned: At Nature Heredity Mike Behe vindicated but not cited At Nature Heredity: Discoveries during the subsequent two decades have continued to support the idea that loss of function contributes to adaptation (Murray 2020), with cases of adaptive or beneficial loss of function being discovered across diverse organisms, genes, traits, and environments.”