Innovation, Speciation: strange DNA finding (Evolution)

by David Turell , Sunday, November 25, 2018, 21:22 (1972 days ago) @ David Turell

Studies of genome wide DNA decoding suggest species reinvent themselves at intervals of
1-200,000 years:

https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html

"It is textbook biology, for example, that species with large, far-flung populations—think ants, rats, humans—will become more genetically diverse over time.

"But is that true?

"The answer is no," said Stoeckle, lead author of the study, published in the journal Human Evolution.

"For the planet's 7.6 billion people, 500 million house sparrows, or 100,000 sandpipers, genetic diversity "is about the same," he told AFP.

"The study's most startling result, perhaps, is that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago.

"This conclusion is very surprising, and I fought against it as hard as I could," Thaler told AFP.

"That reaction is understandable: How does one explain the fact that 90 percent of animal life, genetically speaking, is roughly the same age?

***

"Mitochondria contain 37 genes, and one of them, known as COI, is used to do DNA barcoding.

"Unlike the genes in nuclear DNA, which can differ greatly from species to species, all animals have the same set of mitochondrial DNA, providing a common basis for comparison.

***

"On the one hand, the COI gene sequence is similar across all animals, making it easy to pick out and compare.

"On the other hand, these mitochondrial snippets are different enough to be able to distinguish between each species.

***

"In analysing the barcodes across 100,000 species, the researchers found a telltale sign showing that almost all the animals emerged about the same time as humans.

***

"Which brings us back to our question: why did the overwhelming majority of species in existence today emerge at about the same time?

"Environmental trauma is one possibility, explained Jesse Ausubel, director of the Program for the Human Environment at The Rockefeller University.

"'Viruses, ice ages, successful new competitors, loss of prey—all these may cause periods when the population of an animal drops sharply," he told AFP, commenting on the study.

"'In these periods, it is easier for a genetic innovation to sweep the population and contribute to the emergence of a new species."

"But the last true mass extinction event was 65.5 million years ago when a likely asteroid strike wiped out land-bound dinosaurs and half of all species on Earth. This means a population "bottleneck" is only a partial explanation at best.

***

"The simplest interpretation is that life is always evolving," said Stoeckle.

"'It is more likely that—at all times in evolution—the animals alive at that point arose relatively recently."

"In this view, a species only lasts a certain amount of time before it either evolves into something new or goes extinct.

"And yet—another unexpected finding from the study—species have very clear genetic boundaries, and there's nothing much in between.

"'If individuals are stars, then species are galaxies," said Thaler. "They are compact clusters in the vastness of empty sequence space.'"

"The absence of "in-between" species is something that also perplexed Darwin, he said."

Comment: The 'inbetween' is the gaps we see in the fossil record. This might explain, in a way, how the gaps occur, but not the underlying cause. God in action?