Balance of nature: viruses are a vital component (Introduction)

by David Turell , Monday, April 16, 2018, 19:02 (2412 days ago) @ David Turell

An essay on why they are necessary and can drive evoluion:

https://www.nytimes.com/2018/04/13/science/virosphere-evolution.html

"Each day, they calculated, some 800 million viruses cascade onto every square meter of the planet.

"Most of the globe-trotting viruses are swept into the air by sea spray, and lesser numbers arrive in dust storms.

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"Generally it’s assumed these viruses originate on the planet and are swept upward, but some researchers theorize that viruses actually may originate in the atmosphere. (There is a small group of researchers who believe viruses may even have come here from outer space, an idea known as panspermia.)

"Whatever the case, viruses are the most abundant entities on the planet by far. While Dr. Suttle’s team found hundreds of millions of viruses in a square meter, they counted tens of millions of bacteria in the same space.

"Mostly thought of as infectious agents, viruses are much more than that. It’s hard to overstate the central role that viruses play in the world: They’re essential to everything from our immune system to our gut microbiome, to the ecosystems on land and sea, to climate regulation and the evolution of all species. Viruses contain a vast diverse array of unknown genes — and spread them to other species.

"Last year, three experts called for a new initiative to better understand viral ecology, especially as the planet changes. “Viruses modulate the function and evolution of all living things,” wrote Matthew B. Sullivan of Ohio State, Joshua Weitz of Georgia Tech, and Steven W. Wilhelm of the University of Tennessee. “But to what extent remains a mystery.”

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"The virus injects its own DNA into the host; sometimes that new genes are useful to the host and become part of its genome.

"Researchers recently identified an ancient virus that inserted its DNA into the genomes of four-limbed animals that were human ancestors. That snippet of genetic code, called ARC, is part of the nervous system of modern humans and plays a role in human consciousness — nerve communication, memory formation and higher-order thinking. Between 40 percent and 80 percent of the human genome may be linked to ancient viral invasions.

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“'If you could weigh all the living material in the oceans, 95 percent of it is stuff is you can’t see, and they are responsible for supplying half the oxygen on the planet,” Dr. Suttle said.

"In laboratory experiments, he has filtered viruses out of seawater but left their prey, bacteria. When that happens, plankton in the water stop growing. That’s because when preying viruses infect and take out one species of microbe — they are very specific predators — they liberate nutrients in them, such as nitrogen, that feed other species of bacteria. In the same way, an elk killed by a wolf becomes food for ravens, coyotes and other species. As plankton grow, they take in carbon dioxide and create oxygen.

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"Viruses help keep ecosystems in balance by changing the composition of microbial communities. As toxic algae blooms spread in the ocean, for example, they are brought to heel by a virus that attacks the algae and causes it to explode and die, ending the outbreak in as little as a day.

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"When species disappear, the changes can ripple through an ecosystem. A textbook example is a viral disease called rinderpest.

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"The Italian army brought a few cattle into North Africa, and in 1887 the virus took off across the continent, killing a broad range of cloven-hoofed animals from Eritrea to South Africa — in some cases wiping out 95 percent of the herds.

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“'Almost instantaneously, rinderpest swept away the wealth of tropical Africa,” wrote John Reader in his book “Africa: A Biography of a Continent.”

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“'Viruses aren’t our enemies,” Dr. Suttle said. “Certain nasty viruses can make you sick, but it’s important to recognize that viruses and other microbes out there are absolutely integral for the ecosystem.”

Comment: Viruses are a necessary part of the ecosystem, and may be God's tool to drive evolution. Never ask why God would have made viruses; not evil.