Privileged planet: plate tectonics drive evolution (Introduction)

by David Turell , Sunday, September 15, 2024, 18:30 (70 days ago) @ David Turell

At least with the Coelacanth fish:

https://phys.org/news/2024-09-exceptional-fish-fossil-rethink-earth.html

"Coelacanths are deep-sea fish that live off the coasts of southern Africa and Indonesia and can reach up to two meters in length. For a long time, scientists believed they were extinct.

"In new research published in Nature Communications, we reveal the best-preserved coelacanth fossil ever found from the ancient period hundreds of millions of years ago when these ancient sea-dwellers first evolved. The fossil comes from the Gogo Formation on Gooniyandi Country in northern Western Australia.

"We also studied the evolution of all the hundreds of coelacanth species we know from the fossil record to find out what drove the creation of new species across the eons.

"The answer came as a surprise: the greatest influence on coelacanth evolution was not ocean temperature or oxygen levels but tectonic activity. When the vast plates of Earth's crust were moving around more, new species were more likely to appear.

"Coelacanths are "lobe-finned" fish, which means they have robust bones in their fins a bit like the bones in our arms. Scientists believe they are more closely related to tetrapods (animals with backbones and four limbs, such as frogs, emus and humans) than to most other fishes.

"Coelacanths have been around for a long time. The oldest known fossils are more than 410 million years old. But because these fossils are mostly fragments, we don't know a lot about what the earliest coelacanths were like.

"Later, during the age of dinosaurs which began around 250 million years ago, coelacanths became more diverse. In total, we have found traces of more than 175 fossil species from all over the globe.

***

"Our study of the new species led us to analyze the evolutionary history of all known coelacanths. In doing so, we calculated the rates of evolution across their 410 million year history.

We found that coelacanths have generally evolved slowly, with a few intriguing exceptions.

"Furthermore, we analyzed a series of environmental factors that we considered potential candidates for influencing coelacanth evolutionary rates. These included tectonic plate activity, ocean temperatures, water oxygen levels, and atmospheric carbon dioxide levels.

"Of all the variables we looked at, the one with the greatest influence on the rate of coelacanth evolution was tectonic plate activity. New species of coelacanth were more likely to evolve during periods of heightened tectonic activity, as seismic movement transformed habitats. (my bold)

"Along with our analysis of all fossil Coelacanths, we also had a close look at the two living species, Latimeria chalumnae and Latimeria menadoensis.

"At first glance, these fish look almost identical to some of their counterparts from hundreds of millions of years ago. However, on closer analysis we could see they were in fact distinct from their extinct relatives.

:While Latimeria has essentially ceased evolving new features, the proportions of its body and the details of its DNA are still changing a little. So perhaps it's not a "living fossil" after all."

Comment: plate tectonics are vital for life to appear, so this finding in Coelacanths is not surprising. Their current minor adaptations fit my thinking that major speciation is finished. Continental drift is very slow now which makes any new speciation very slow to appear if at all.