Did Radiation Affect Evolution?

[steve_bank]

https://arxiv.org/pdf/1403.7303.pdf
https://en.wikipedia.org/wiki/Gamma_ray
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1203310/

Gamma radiation is mutagenic. Did it spark the Cambrian explosion in diversity?

 

[skepticalbip]

I would guess that it was the first appearance of multi-cell organisms (~600 million years ago) that sparked the Cambrian explosion.

 

[Jobar]

Recently I watched a YT video on Snowball Earth-
[YOUTUBE]https://www.youtube.com/watch?v=TNrqy5vlVPs[/YOUTUBE]

The latest episode when the Earth's oceans froze clear down to the equator ended some 630 million years ago; there is some evidence that this has happened more than once. But mention is made in the video that the 'defrosting' of the planet may have had something to do with the development of multicellular organisms. Interesting speculations.

 

[phands]

Radiation no doubt played a part in causing mutations that led to genetic change before and after the CE, but it most likely didn't cause it.

A larger contributing factor is thought to be rising levels of free oxygen in the atmosphere, which was done by cyanobacteria evolving photosynthesis and excreting oxygen over billions of years. It's thought that low oxygen levels prevented the evolution of large and complex fauna. Ironically, free oxygen leads to atmospheric ozone, which reduces deadly UV radiation considerably, and the ozone layer formed around the time of the CE. This, of course, doesn't account for terrestrial radiation, which may well have been (and still is) a mutation-inducing factor, but the majority of the planet isn't (fortunately) soaked in radiation.

Another factor being theorized is the increase in Calcium levels in sea water, which allowed shells and bones to develop.

So....no...radiation didn't affect evolution the process, but it was for sure a factor in causing mutations which evolution "worked" with.

 

[Peez]

https://arxiv.org/pdf/1403.7303.pdf
https://en.wikipedia.org/wiki/Gamma_ray
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1203310/

Gamma radiation is mutagenic. Did it spark the Cambrian explosion in diversity?

Among evolutionary biologists it is not generally thought that genetic variance limits evolution that much (though there are certainly exceptions). In other words, evolution is not metaphorically sitting around waiting for the right mutation to allow it to go. Much more likely would be new opportunities, new niches, that allow rapid evolution of novel forms. Often these new niches are contingent on what has already evolved.

An increase in mutation rate increases the chance of a 'useful' mutant appearing in a limited population, but in large populations I would not expect that an increase in mutation rate would necessarily lead to an increase in rates of evolution.

Peez

P.S.: It is worth noting that the first article linked to does not seem to include any biologists (let alone evolutionary biologists) as authors.

P.P.S.: The lack of biologists shows with blatantly false claims, such as "There exists a unique “mass genesis” in Earth’s history, that is the Cambrian explosion, the so-called “bio-evolution’s big bang”, where diversification of life accentuated from around 540 to 520 Mya [1]. All major phila[sic] were established during that time".

 

[steve_bank]

As I understand it normal mutation rates can not account for all of evolution.

Of cause, evolution is not a directd process.

 

[Peez]

As I understand it normal mutation rates can not account for all of evolution.

As I mentioned there are cases in which evolution might be limited by mutation rates, but this is thought to be the exception rather than the rule. There is nothing about the “Cambrian explosion“ that cannot be explained by “normal“ mutation rates. As an exercise, it has been estimated that each human is born with an average 128 mutations (new ones, not including mutations that occurred in the parents or earlier generations). Let me speculate a little...

There could easily be 10^19 “worms” on the planet at the start of the Cambrian, imagine that each has a mere 10 mutations each generation, and a generation time of one month, over 10 million years (the Cambrian Period is actually lasted more than 55 million years): this works out to about 10^27 mutations (just in the survivors, we are not considering all those born). If we assume about 20,000 genes in a “worm” genome, this would work out to something like 10^22 mutations in each and every gene (in addition to the genetic diversity that these “worms” started with at the beginning of the Cambrian Period). It is fair to suggest that this is a lot of genetic diversity.

Of cause, evolution is not a directd process.

Agreed, it is only “directed“ in the sense that natural selection may direct it.

Peez

 

[skepticalbip]

I would think that since multicellular organisms had just arose there would be a lot of possible environmental niches that earlier single celled organisms could not take advantage of. This would mean that there would be no competition for those niches. Without competition, the new forms would have a much better chance of survival than if they had had to compete with forms that were already well adapted to that niche.

 

[Peez]

I would think that since multicellular organisms had just arose there would be a lot of possible environmental niches that earlier single celled organisms could not take advantage of. This would mean that there would be no competition for those niches. Without competition, the new forms would have a much better chance of survival than if they had had to compete with forms that were already well adapted to that niche.

Definitely, there was a huge assortment of new niches that were unoccupied, and therefore selection could favour a wide variety of new forms.

Peez

 

[steve_bank]

As I understand it normal mutation rates can not account for all of evolution.

As I mentioned there are cases in which evolution might be limited by mutation rates, but this is thought to be the exception rather than the rule. There is nothing about the “Cambrian explosion“ that cannot be explained by “normal“ mutation rates. As an exercise, it has been estimated that each human is born with an average 128 mutations (new ones, not including mutations that occurred in the parents or earlier generations). Let me speculate a little...

There could easily be 10^19 “worms” on the planet at the start of the Cambrian, imagine that each has a mere 10 mutations each generation, and a generation time of one month, over 10 million years (the Cambrian Period is actually lasted more than 55 million years): this works out to about 10^27 mutations (just in the survivors, we are not considering all those born). If we assume about 20,000 genes in a “worm” genome, this would work out to something like 10^22 mutations in each and every gene (in addition to the genetic diversity that these “worms” started with at the beginning of the Cambrian Period). It is fair to suggest that this is a lot of genetic diversity.

Of cause, evolution is not a directd process.

Agreed, it is only “directed“ in the sense that natural selection may direct it.

Peez

Using anthropomorphisms to describe physical process is OK. It is common.

The Cambrian periodic was an overwhelming diversity, was it not?

 

[J842P]

As I understand it normal mutation rates can not account for all of evolution.

Of cause, evolution is not a directd process.

You understand incorrectly.

 

[steve_bank]

As I understand it normal mutation rates can not account for all of evolution.

Of cause, evolution is not a directd process.

You understand incorrectly.

There is no purpose to evolution. There is no purpose to the universe, unless you are some kind of theist or agnostic.

We sometimes speak as if there is some kind of intelligence to it but it is just a manner of speaking. It is a blind chemical process. The process of evolution in a species at the genetic level does not evaluate the environment and make intentional genetic adaptations. Higher levels of species like humans, chimps, dolphins, Orcas and others can and do evolve social behavior that enhances survival. Group coordinated hunting.

 

[bilby]

The whole 'radiation leads to mutants' idea seems to owe more to the rampant radiophobia since the Hiroshima bombing than it does to reality.

While radiation can increase mutation rates, there is no shortage of mutations in its absence, and so no reason why it should be invoked as a necessary or even likely cause of observed circumstances in which new forms arise, even at the rates seen in the Cambrian Explosion.

Radiation initiated mutations are a feature of comic books and Godzilla movies, rather than of actual evolutionary biology.

 

[Peez]

As I mentioned there are cases in which evolution might be limited by mutation rates, but this is thought to be the exception rather than the rule. There is nothing about the “Cambrian explosion“ that cannot be explained by “normal“ mutation rates. As an exercise, it has been estimated that each human is born with an average 128 mutations (new ones, not including mutations that occurred in the parents or earlier generations). Let me speculate a little...

There could easily be 10^19 “worms” on the planet at the start of the Cambrian, imagine that each has a mere 10 mutations each generation, and a generation time of one month, over 10 million years (the Cambrian Period is actually lasted more than 55 million years): this works out to about 10^27 mutations (just in the survivors, we are not considering all those born). If we assume about 20,000 genes in a “worm” genome, this would work out to something like 10^22 mutations in each and every gene (in addition to the genetic diversity that these “worms” started with at the beginning of the Cambrian Period). It is fair to suggest that this is a lot of genetic diversity.

Agreed, it is only “directed“ in the sense that natural selection may direct it.

Peez

Using anthropomorphisms to describe physical process is OK. It is common.

Whether it is OK or not is a matter of opinion, I suppose, but I do not have a special problem with it. That being said, I am not clear on your point here.

The Cambrian periodic was an overwhelming diversity, was it not?

If you meant to post 'In the Cambrian Period there was a great increase in animal diversity, was there not?' then I would agree that there was. This is what the Cambrian explosion was, again I am not clear on your point here.

Peez

 

[steve_bank]

Whether it is OK or not is a matter of opinion, I suppose, but I do not have a special problem with it. That being said, I am not clear on your point here.

The Cambrian periodic was an overwhelming diversity, was it not?

If you meant to post 'In the Cambrian Period there was a great increase in animal diversity, was there not?' then I would agree that there was. This is what the Cambrian explosion was, again I am not clear on your point here.

Peez

I thought you were labling me as one who believes evolution was somehow guided.


And does estimates of mutation rates without external causes account for the rapid rise of diversity?
I saw an animation on a show based on fossil reconstruction of marine life. Extreme variations and adaptations.

 

[Peez]

steve_bank:
I thought you were labling me as one who believes evolution was somehow guided.

I am sorry if I gave that impression, it was not my intent.

And does estimates of mutation rates without external causes account for the rapid rise of diversity?
I saw an animation on a show based on fossil reconstruction of marine life. Extreme variations and adaptations.

I am suggesting that the rapid increase in animal diversity during the Cambrian Period was not accounted for by any mutation rate ("normal" mutation rate or high mutation rate). The mutation rates we see today generate more genetic variation than would be needed to allow rates of evolution greater than occurred during the Cambrian Explosion. There is no reason to think that mutation rates were limiting rates of evolution before the Cambrian Period. It is perhaps like an increase in highway speed limit from 100 kph to 110 kph making bicycles on the highway move faster: it won't because the posted limit was never what stopped the bicycles from going faster.

Note that a great deal of animal diversity evolved long after the Cambrian Period (e.g., there were no terrestrial chordates until much later, let alone mammals). Also note that there was no notable increase in the diversity of other organisms (e.g., algae) during the Cambrian Explosion.

Peez

 

[steve_bank]

Life evolves to fill energy niches.

The main argument against the Loch Ness monster is there is not enough food to support large mass animals.

The Cambrian era would not have been sustainable. There would be winners and losers. Not enough energy to support the total biomass.

 

[skepticalbip]

Life evolves to fill energy niches.

The main argument against the Loch Ness monster is there is not enough food to support large mass animals.

The Cambrian era would not have been sustainable. There would be winners and losers. Not enough energy to support the total biomass.

There is much more biomass now than there was during the Cambrian explosion when there were no land plants or animals.

And then more species does not mean more biomass. A billion individuals in one species could be the same biomass as a thousand species with a million individuals in each species.

But then I agree that the Cambrian explosion couldn't continue, not because of limited energy but because of limited environmental niches without stiff competition for that niche. It is the fittest that survive. After the Cambrian explosion there were species well adapted to their environmental niche that easily out competed newer arrivals. Before and during the Cambrian explosion, those niches were empty so no competition.

 

[Peez]

Life evolves to fill energy niches.

There is more to niches than energy, but certainly different energy sources could play a role in niche diversification.

The main argument against the Loch Ness monster is there is not enough food to support large mass animals.

I would argue that there are other good arguments, but that one might not be bad.

The Cambrian era would not have been sustainable. There would be winners and losers. Not enough energy to support the total biomass.

Is there any indication that there was an increase in biomass during the Cambrian Period? I was not aware of any such trend.

Peez

 

[steve_bank]

By niche I mean

Birds beaks adapted to get nectar from one particular plant
giraffes

Is there more marine bio mass today then Cambrian?