Not by adding to it. Everyone seems to be talking about devolution (“reductive evolution”) these days. From ScienceDaily:
“This is the first large genome project like this that actually looks at hundreds of different eukaryotic species, not different individuals or isolates of the same species,” says Chris Todd Hittinger, a UW-Madison genetics professor and one of the senior authors of the study. “Budding yeasts, despite their phenotypic similarity, are very different from one another genetically. They’re as different from one another as all animals or all plants are from one another.”
Collecting such a deep pool of yeast types gave researchers enough information to use comparisons of the shifting genetics to redraw the budding yeast family tree into a dozen major branches and paint a detailed picture of their past.
The yeasts are thought to have got started about 400 million years ago.
The researchers examined their yeasts for 45 traits representing their ability to process a variety of yeast foods — different sources of carbon and nitrogen necessary to store energy and build cells. Tracking back the evolutionary paths of modern yeasts suggests the common ancestor yeast had a metabolism that could work with a varied diet.
“We have a more consistent picture now of the variations of carbon and nitrogen sources across the modern species,” says Dana Opulente, a postdoctoral researcher in Hittinger’s lab who redid much of the trait-testing work of a century of yeast researchers for the Cell study. “They show us that this ancestor yeast would have been able to use a wider array of sugars than modern budding yeasts.”
Modern yeasts have narrowed their appetites in a process called reductive evolution, losing quite a few of those 45 traits as they specialized to flourish in their particular niches.
“To pick on the model budding yeast, S. cerevisiae has one of the more reduced genomes,” Hittinger says. “It lacks many of the metabolic capabilities that other budding yeasts have.” Paper. (paywall) – Xing-Xing Shen, Dana A. Opulente, Jacek Kominek, Xiaofan Zhou, Jacob L. Steenwyk, Kelly V. Buh, Max A.B. Haase, Jennifer H. Wisecaver, Mingshuang Wang, Drew T. Doering, James T. Boudouris, Rachel M. Schneider, Quinn K. Langdon, Moriya Ohkuma, Rikiya Endoh, Masako Takashima, Ri-ichiroh Manabe, Neža Čadež, Diego Libkind, Carlos A. Rosa, Jeremy DeVirgilio, Amanda Beth Hulfachor, Marizeth Groenewald, Cletus P. Kurtzman, Chris Todd Hittinger, Antonis Rokas. Tempo and Mode of Genome Evolution in the Budding Yeast Subphylum. Cell, 2018; DOI: 10.1016/j.cell.2018.10.023 More.
If losing complex traits is a reliable and successful form of evolution, how did successful life forms acquire great complexity in the past, when there was less time to evolve?
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See also: John Sanford gives lecture at NIH on mutations and human health Sanford has a great deal to say about genetic entropy and devolution.
A peek at Mike Behe’s new book Darwin Devolves We’re told that the basic thesis is, The First Rule of Adaptive Evolution: Break or blunt any functional gene whose loss would increase the number of offspring.
Devolution: Worm gives up sexual reproduction, loses 7000 genes
Giant shipworm found alive is example of devolution
Devolution: Getting back to the simple life