After Pangaea's Break-up, Biology and Geology Agree on a Date

[essentialsaltes]

No, it's not the personals column, it's science:

They founded their investigation on the basis that “the molecular clock dates, for the divergences of species whose geographical ranges were divided, should agree with the palaeomagnetic dates for the continental separations,” reports the study. Looking at the phylogenetic divergence dates of 42 pairs of specifically chosen vertebrate taxa (chosen for their reduced ability to disperse), the team confirmed that the phylogenetic trees’ divergence dates of continent-bound terrestrial and freshwater vertebrates line up with the palaeomagnetic dates of continental separation.

"After excluding species that could easily move between continents, a new comparison of these two independent dating methods, applied to the breakup of Pangaea over the past 180 million years, finds good agreement between the two methods,” said Ms. McIntyre from the ANU Research School of Astronomy and Astrophysics. “Geological dating provides important independent support for the relatively new field of using genetic trees to date biological divergences.”

 

[juvenissun]

No, it's not the personals column, it's science:

They founded their investigation on the basis that “the molecular clock dates, for the divergences of species whose geographical ranges were divided, should agree with the palaeomagnetic dates for the continental separations,” reports the study. Looking at the phylogenetic divergence dates of 42 pairs of specifically chosen vertebrate taxa (chosen for their reduced ability to disperse), the team confirmed that the phylogenetic trees’ divergence dates of continent-bound terrestrial and freshwater vertebrates line up with the palaeomagnetic dates of continental separation.

"After excluding species that could easily move between continents, a new comparison of these two independent dating methods, applied to the breakup of Pangaea over the past 180 million years, finds good agreement between the two methods,” said Ms. McIntyre from the ANU Research School of Astronomy and Astrophysics. “Geological dating provides important independent support for the relatively new field of using genetic trees to date biological divergences.”

Not sure how does the molecular clock work.

 

[essentialsaltes]

Not sure how does the molecular clock work.

I believe the idea is this:

We have some estimates for how rapidly mutations accrue in the genome. So if we compare the codes for 'the same' protein between two different species, we can count how many differences there are, and use the mutation rate to estimate the length of time since these species diverged. Doing it for multiple proteins would allow you to build up a more robust statistical model for estimating these ages.

Here the physical separation of the landmasses acts to separate one breeding population into two, so the divergence comes from that point in time.

 

[morse86]

Let's see if the Pangaea exists or if it's just a bunch of poorly done $cience garbage. What does Wikipedia say about "proof" of the Pangaea:

Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart.

Additional evidence for Pangaea is found in the geology of adjacent continents, including matching geological trends between the eastern coast of South America and the western coast of Africa.

Is this what you call scientific evidence?!?!?!? What utter rubbish. This is so embarrassing for real scientists.

Both of those "observations" can be explained a hundred different ways (black swan theory).

The Pangaea does not exist, it's a hoax.

 

[Ygrene Imref]

Let's see if the Pangaea exists or if it's just a bunch of poorly done $cience garbage. What does Wikipedia say about "proof" of the Pangaea:


Is this what you call scientific evidence?!?!?!? What utter rubbish. This is so embarrassing for real scientists.

Both of those "observations" can be explained a hundred different ways (black swan theory).

The Pangaea does not exist, it's a hoax.

Or, if it did exist, the mechanisms to turn Terra Firma into what it is now were not necessarily slow, random, unintelligible and constant.

 

[essentialsaltes]

Is this what you call scientific evidence?!?!?!?

Yes.

 

[morse86]

Yes.

Then you are believe that rubbish by faith, don't call that science.

A great flood could've accounted for the distance between the fossils. There are hundreds of other theories. Matching geological trends is just a joke. This is not science, it's religion.

 

[juvenissun]

I believe the idea is this:

We have some estimates for how rapidly mutations accrue in the genome. So if we compare the codes for 'the same' protein between two different species, we can count how many differences there are, and use the mutation rate to estimate the length of time since these species diverged. Doing it for multiple proteins would allow you to build up a more robust statistical model for estimating these ages.

Here the physical separation of the landmasses acts to separate one breeding population into two, so the divergence comes from that point in time.

Sounds good. Thanks.
But what controls the mutation rate?
I feel this technique may be quite immature to be used beyond the Holocene.

With that said, I do think the drift of continents significantly affected life on the earth. There is a hint of this feature in the Bible. Of course, it is in the Book of Genesis.

 

[Jimmy D]

A great flood could've accounted for the distance between the fossils.

How?

 

[essentialsaltes]

Sounds good. Thanks.
But what controls the mutation rate?

The genetic copying machinery has a measurable error rate, and this is the most significant factor in the mutation rate.

 

[xianghua]

I believe the idea is this:

We have some estimates for how rapidly mutations accrue in the genome. So if we compare the codes for 'the same' protein between two different species, we can count how many differences there are, and use the mutation rate to estimate the length of time since these species diverged. Doing it for multiple proteins would allow you to build up a more robust statistical model for estimating these ages.

are you sure? what about this one:

Phylogeny: Rewriting evolution

or this?:

Turtles more closely related to birds than lizards and snakes, genetic evidence shows

 

[essentialsaltes]

are you sure?

Yes, I am reasonably sure the dating method is based on the scenario I described.

what about this one:

or this?:

They have nothing to do with this dating method, so I'm puzzled -- I'm not sure what my reaction was supposed to be. New genetic methods provide us with new information that may be in conflict with what we thought before? Hardly a surprise.

 

[juvenissun]

The genetic copying machinery has a measurable error rate, and this is the most significant factor in the mutation rate.

How do we know the rate is a constant since Cretaceous time?

 

[essentialsaltes]

How do we know the rate is a constant since Cretaceous time?

I'm not an expert, so someone more knowledgeable may be able to help. I believe the gene-copying apparatus is well-conserved, so that it is very similar across many different types of organisms that diverged long ago, suggesting the apparatus was largely the same way back when as it is now. And biochemistry is just chemistry which is just physics.

 

[juvenissun]

I'm not an expert, so someone more knowledgeable may be able to help. I believe the gene-copying apparatus is well-conserved, so that it is very similar across many different types of organisms that diverged long ago, suggesting the apparatus was largely the same way back when as it is now. And biochemistry is just chemistry which is just physics.

We know some species evolved very fast and some evolved very slow. Is that an evidence to suggest a significant rate variation of mutation?

 

[Tanj]

We know some species evolved very fast and some evolved very slow. Is that an evidence to suggest a significant rate variation of mutation?

The article is not suggesting a single molecular rate for every species. You are correct that different species fix mutations at different rates. The methodology described here allows us to set the rate for some of them, and it's not the same for all.

 

[Job 33:6]

Nice post, what is the source of the original article?

 

[Job 33:6]

How do we know the rate is a constant since Cretaceous time?

This is for anyone in the discussion. Mutation rates aren't necessarily constant. There are estimated or averaged rates of mutation. There may even be a proposed upper and lower limits to the rate at which an organism can mutate. But not just a set rate like 5 mutations per day or anything like that.

And these mutation rates can also be correlated with morphological changes in fossil sequences of the fossil record.

 

[xianghua]

And these mutation rates can also be correlated with morphological changes in fossil sequences of the fossil record.

im not sure. coelacanth and lungfish for instance are very similar. but they split off about 400my. when human and a bird suppose to be more closer from phylogenetic prespective then coelacanth to a lungfish.

 

[essentialsaltes]

Nice post, what is the source of the original article?

Global biogeography since Pangaea