evolution: symbiosis and metabolism swapping (Introduction)

by David Turell , Tuesday, May 03, 2022, 23:36 (717 days ago) @ David Turell

Not strictly Darwin mutation processes:

https://phys.org/news/2022-05-biologists-traits-tree-life.html

modern research suggests that the game of life is far more complicated than we had anticipated. There are opportunities to swap cards and even steal other players' hands.

Researchers at UC Santa Barbara have been investigating the effects of this strategy, particularly the ability to acquire metabolic pathways. The scientists found that adopting another metabolism can have major competitive consequences, with ramifications to a species' evolution and ecology.

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Examples of acquired metabolisms abound in nature. Some are familiar, like the microbes in a cow's gut that enable it to digest cellulose. Others are more common but less well-known. For instance, consider the symbiotic fungi that help plants source minerals from the soil. And then there are truly unusual acquired metabolisms, like sea slugs that steal chloroplasts from their food so they can photosynthesize.

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The authors considered two single-celled eukaryotes (organisms whose cells contain a nucleus). The first, a species in the genus Colpidium, subsists on a diet of smaller microbes. The second, Paramecium bursaria, shares its counterpart's diet, but had also acquired the ability to photosynthesize at some point in the past.

The researchers analyzed the two microbes under four different light conditions. Colpidium got along fine no matter the setting; however, P. bursaria fared much better under brighter conditions, where it could take advantage of its unique ability.

Then the scientists pitted the microbes against each other. They observed a gradient of competitive advantage across different light levels. In the dark, Colpidium outcompeted P. bursaria. Meanwhile, under bright conditions, P. bursaria dominated.

"I think it gets to this idea that you can't be good at everything," said co-author Holly Moeller, an assistant professor in the Department of Ecology, Evolution and Marine Biology. Adapting to an acquired metabolism might have come at the expense of P. bursaria's hunting prowess. But at high light levels, the boost from photosynthesis more than offsets this handicap.

Remarkably, the two microbes were able to coexist under intermediate light conditions. P. bursaria's acquired phototrophy enabled it to avoid direct competition with Colpidium in what scientists call "niche partitioning."

"The results demonstrate that symbiosis and acquired metabolism can drastically affect community dynamics. "Expanding on your metabolic repertoire has cascading implications on how you can make a living, and the extent to which you're going to shove other organisms out of the way," Moeller said.

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"It's important to study how acquired metabolisms influence evolution and ecology because they're a fundamental part of life on Earth. For instance, we generally think of photosynthesis as a characteristic of plants. "But that's an ancient acquisition, too," said Moeller. "They inherited their chloroplasts from a eukaryotic ancestor that domesticated a cyanobacterium."

"'Mitochondria are also acquired from bacteria," added Hsu. In fact, both of these organelles have their own DNA, separate from a cell's nuclear genome.

"'This is how eukaryotes have been playing the game for some 2 billion years," Moeller remarked. And our simpler counterparts, prokaryotes, arguably engage in even more biological card-swapping. Many are able to directly share DNA in a process known as "horizontal gene transfer.'"

Comment: it is not just developing chance mutations. These combinations have purpose and easily can be seen as due to God's designing work.