Oxygen and the Cambrian (Evolution)

by David Turell @, Sunday, December 19, 2021, 15:30 (32 days ago) @ dhw
edited by David Turell, Sunday, December 19, 2021, 15:42

DAVID: (under "Cellular intelligence"): Yes, all species can adapt, but are still the same species.

dhw: We are trying to explain speciation. Do you think it was sheer coincidence that oxygen appeared in large quantities and new species appeared at the same time? Or do you think the new species appeared BEFORE the increase in oxygen?

DAVID: Coincidence doesn't speciate. Oxygen was around in large amounts long before the Cambrian.

dhw: I’m glad you agree that it is NOT coincidence. What happened before the Cambrian is irrelevant to what happened during the Cambrian. If the oxygen theory is true, this leaves you with my second question: do you think your God created the new species “de novo” BEFORE the increase in oxygen? Here is an interesting article in support of the link between oxygen and speciation as well as extinction:

Rapid Oxygen Changes Fueled an Explosion in Ancient Animal ...


QUOTES: Geological slice by geological slice, the researchers compared the modeled oxygen levels and the diversity of fossils, revealing a volatile history. In the span of about 10 million years, between 524 and 514 million years ago, this shallow Siberian sea underwent five distinct oxygen spikes.

“These fluctuations are fairly extreme,” said He, explaining that each spike and dip constituted about a 50 percent increase or decrease in oxygen levels. “Previous studies suggest that oxygen levels during the Cambrian were about 40 percent of today’s atmospheric levels,” He said. “Fifty percent swings are pretty enormous.”

Each pulse of oxygenation corresponded with a local high in biodiversity, while dips in oxygen levels were associated with higher rates of extinction. For example, a pulse between 521 and 522 million years ago was associated with the appearance of numerous shelled animals, including trilobites and bivalved arthropods. A couple of million years later, the next pulse was coincident with a rise in large predatory arthropods and evidence of increased predatory behavior.

“The Cambrian explosion wasn’t a singular event. It happened in spurts, in rises and falls,” He said. “In our study, the rise and fall of oxygen levels correlated with these spurts of [evolutionary] radiation.

For Wood, “The data pretty clearly show a positive correlation.” She added, “The more interesting question is: why?” One explanation is that these pulses of oxygenation rapidly expanded how much of the shallow seas were habitable. More physical space gives life more breathing room to diversify, literally and figuratively. According to He, each pulse of oxygen allowed an expansion of forms and ways of living. This in turn created more opportunity for ecological interactions, like “coevolutionary arms races” between sets of predators and prey, that could further accelerate diversification. (dhw's bolding)

dhw: I would regard this as typical of evolution in general: organisms RESPOND to environmental change in three possible ways: adaptation, innovation or death.

I'm sure I presented this article here when it appeared, and my comment remains the same as before. First, thanks for re-finding it. Second: oxygen levels, when high, allow for more complex organisms. But the drive for complexity comes from something else, which we debate. I'll stick with God.

As the article says: He [researcher] emphasizes that increased oxygen isn’t the sole cause of increased diversity. Once complexity evolved, it could compound itself, driven by ecological interactions. But He argues that for this to be possible, higher oxygen levels were necessary. I agree. Not causing but allowing

https://www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient-anim... (this address should work, the one above didn't)

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