The Scientific Method & Macroevolution?

PsychoSarah · Apr 8, 2015

lewiscalledhimmaster said:
Okay.

Moving on.

SELECTION

A very poorly thought out choice of word for how certain traits are more advantageous than others to survive in an environment, and thus are more likely to get passed down to future generations than traits which make survival and reproduction harder.

For example, at the North Pole, keeping warm is very important to survival, hence, any creature within a population without a trait that could accomplish that would die before reproducing, leaving only those capable of surviving in that environment to reproduce and increase the frequency of those traits within the population.

Of course, most traits aren't universally advantageous, so "super creature/evolution endgame" will not occur. Even our intelligence, which seems so great one might think it has no disadvantages, does have problems. For example, these big brains of ours are energy hogs, so an environment with very little food would not work out.

sfs · Apr 8, 2015

PsychoSarah said:
I am also aware of the number of multicellular prokaryotes, but we both know that they are glorified petri dish colonies compared to multicellular eukaryotes. I never intended to give the impression that NO prokaryotes were multicellular, but they never come close to the specialization that we see in eukaryotes.

My comment about multicellular prokaryotes was for his benefit, not yours.

sfs · Apr 8, 2015

PsychoSarah said:
Of course, most traits aren't universally advantageous, so "super creature/evolution endgame" will not occur. Even our intelligence, which seems so great one might think it has no disadvantages, does have problems. For example, these big brains of ours are energy hogs, so an environment with very little food would not work out.

I do wonder if it's also made us more likely to suffer from mental illness.

lewiscalledhimmaster · Apr 11, 2015

PsychoSarah said:
A very poorly thought out choice of word for how certain traits are more advantageous than others to survive in an environment, and thus are more likely to get passed down to future generations than traits which make survival and reproduction harder.

I was so happy to read this stanza. Why? I'm finally finding that some of the stuff I learned since I began studying this, is beginning to take root in my mind. If you knew barren and unfruitful my brain was (with regards to general Biology) in 2008, you'd have shared the moment with me. The right words are important, but the meanings (definitions) really do matter.

PsychoSarah said:
For example, at the North Pole, keeping warm is very important to survival, hence, any creature within a population without a trait that could accomplish that would die before reproducing, leaving only those capable of surviving in that environment to reproduce and increase the frequency of those traits within the population.

I'm having problems with this, because I don't think people evolve those sort of traits. i.e. cold resistance. Surely you mean behaviors, habitats, eating habits etc. ?

PsychoSarah said:
Of course, most traits aren't universally advantageous, so "super creature/evolution endgame" will not occur. Even our intelligence, which seems so great one might think it has no disadvantages, does have problems. For example, these big brains of ours are energy hogs, so an environment with very little food would not work out.

Yes, we have gone to the other extreme and made things that are very bad for us. i.e salt, sugar, certain oils. (don't forget the damned carbohydrates!)

lewiscalledhimmaster · Apr 11, 2015

sfs said:
My comment about multicellular prokaryotes was for his benefit, not yours.

What was it exactly that you wanted to say to me? I read back, but I'm having problems processing so much of what you two are obviously very familiar with. Please dumb a down a tad, if you don't mind? then take it right back up. I don't want to waste too much time reading and re-reading and just sitting here with a bag full of marbles.

sfs · Apr 11, 2015

lewiscalledhimmaster said:
What was it exactly that you wanted to say to me? I read back, but I'm having problems processing so much of what you two are obviously very familiar with. Please dumb a down a tad, if you don't mind? then take it right back up. I don't want to waste too much time reading and re-reading and just sitting here with a bag full of marbles.

I was just pointing out that some prokaryotes (i.e. bacteria) can form simple multicellular organisms. So it's not just eukaryotes that can do that.

justlookinla · Apr 11, 2015

sfs said:
prokaryotes eukaryotes

We have just plain ole coyotes around here that tend to be a nuisance sometimes.

sfs · Apr 11, 2015

justlookinla said:
We have just plain ole coyotes around here that tend to be a nuisance sometimes.

We have Eastern coyotes here. They're larger (they're part wolf) and they can eat Western coyotes for lunch.

lewiscalledhimmaster · Apr 11, 2015

sfs said:
I was just pointing out that some prokaryotes (i.e. bacteria) can form simple multicellular organisms. So it's not just eukaryotes that can do that.

Oh, okay, thanks sfs.

lewiscalledhimmaster · Apr 13, 2015

On to SPECIATION:

lewiscalledhimmaster said:
After tossing the idea of scientific methodology around, I'm back at the primary focus of this thread: MACROEVOLUTION

To break this up into topics for discussion, would it look something like this?

A.
Understand The Mechanisms & How They Affect Populations of Organisms.
B.
Basic minimum mechanisms to consider:
1. Mutation
2. Selection
3. Speciation
C.
Understand why these mechanisms would produce a nested hierarchy, and what a nested hierarchy is.

I hope this quote from Charles Darwin & Evolution, will serve as a good primer for B. 3. Speciation:

'.... We now recognize four mechanisms of speciation which rely on these two factors:

1) Allopatric speciation this is the classic island speciation propsoed by Darwin and later extended, most notably by Ernst Mayr. Individuals of a species migrate to an island and become isolated from their parent population; natural selection then acts to modify the founder population.

2) Peripatric speciation this is much like allopatric speciation but in this case the island doesnt have to be an oceanic island; it could be a isolated mountain top or forest for example.

3) Parapatric speciation this is akin to the sort of thing Darwin imagined happened if a species expands its range and enters a new habitat or niche. Natural selection will favour local adaptation to meet the demands of this new environment.

4) Sympatric speciation this is perhaps what Darwin meant when discussing local adaptation to different environments within a species range. If new variants arise which are better suited to a particular niche they will be favoured by natural selection. ....'*

~~~
* Charles Darwin & Evolution

Loudmouth · Apr 13, 2015

sfs said:
I haven't thought about this subject before. Is the above speculation, or is it based on the literature? I'm skeptical about mitochondria letting some cells provide energy to other cells, since mitochondria produce energy in the form of ATP, which is primarily used (at least as an energy store) within cells, rather than being passed between them. Or such is my rudimentary understanding. Mitochondria due permit cells to fine-tune the energy output (more mitochondria = more available energy).

Eukaryotes have much more complex machinery than prokaryotes it other important ways, though. They have a variety of internal, membrane-bound organelles, i.e. mitochondria, but also the endoplasmic reticulum, Golgi dohickeys, the nucleus. That lets them carry out specialized chemistry and protein processing in dedicated chambers, while bacteria pretty much do everything in a soup. The nucleus sequesters the DNA, permits more complex genome organization (and thus larger genomes) and controls traffic to and from the genes. Basically, there's a whole bunch of stuff going on in eukaryotic cells that lets them have more complex behaviors.

Even so, some prokaryotes manage a form of multicellularity. Look at magnetotactic bacteria, for example.

I would think that selection pressures played a much more important role. For whatever reason, eukaryotes or early symbionts gained the first adaptations that allowed them to be bigger. Once that niche was filled, the only fitness peaks left were for smaller, faster replicating populations.

Loudmouth · Apr 13, 2015

lewiscalledhimmaster said:
On to SPECIATION:

I hope this quote from Charles Darwin & Evolution, will serve as a good primer for B. 3. Speciation:

'.... We now recognize four mechanisms of speciation which rely on these two factors:

1) Allopatric speciation this is the classic island speciation propsoed by Darwin and later extended, most notably by Ernst Mayr. Individuals of a species migrate to an island and become isolated from their parent population; natural selection then acts to modify the founder population.

2) Peripatric speciation this is much like allopatric speciation but in this case the island doesnt have to be an oceanic island; it could be a isolated mountain top or forest for example.

3) Parapatric speciation this is akin to the sort of thing Darwin imagined happened if a species expands its range and enters a new habitat or niche. Natural selection will favour local adaptation to meet the demands of this new environment.

4) Sympatric speciation this is perhaps what Darwin meant when discussing local adaptation to different environments within a species range. If new variants arise which are better suited to a particular niche they will be favoured by natural selection. ....'*

~~~
* Charles Darwin & Evolution

The basic concept is a loss of free genetic flow between lineages. Once there is a road block to new mutations moving between populations, what you inevitably get is different mutations accumulating in each population. Over time, this results in the populations looking more and more different.

A good metaphor is language, at least before the information age. Imagine if you took a group of people, separate them them into two groups, and then not allow them to talk to one another for 2,000 years, what do you think the result will be? More than likely, when these two groups are brought back together, they won't understand each other. Their common ancestral tongue will have changed in each group, and changed in different ways. However, the individual changes were small in that each generation could communicate with the next generation within each population. That is macroevolution. It is the accumulation of different microevolutionary events in different populations. Macroevoution is microevolution + barrier to gene flow.

lewiscalledhimmaster · Apr 13, 2015

Loudmouth said:
The basic concept is a loss of free genetic flow between lineages. Once there is a road block to new mutations moving between populations, what you inevitably get is different mutations accumulating in each population. Over time, this results in the populations looking more and more different.

A good metaphor is language, at least before the information age. Imagine if you took a group of people, separate them them into two groups, and then not allow them to talk to one another for 2,000 years, what do you think the result will be? More than likely, when these two groups are brought back together, they won't understand each other. Their common ancestral tongue will have changed in each group, and changed in different ways. However, the individual changes were small in that each generation could communicate with the next generation within each population. That is macroevolution. It is the accumulation of different microevolutionary events in different populations. Macroevoution is microevolution + barrier to gene flow.

Thank-you for taking time out to explain this to me.

If you can help me, the way you have -- I am sure that anyone who's read your posts here must feel the same way.

Would you now bring it all together in a response to what I called: "C"

C.
Understand why these mechanisms would produce a nested hierarchy, and what a nested hierarchy is.

Loudmouth · Apr 13, 2015

lewiscalledhimmaster said:
Thank-you for taking time out to explain this to me.

If you can help me, the way you have -- I am sure that anyone who's read your posts here must feel the same way.

Would you now bring it all together in a response to what I called: "C"

C.
Understand why these mechanisms would produce a nested hierarchy, and what a nested hierarchy is.

You should think of each species as an isolated island that can not use any of the adaptations that any other population on an island has discovered. They are completely on their own. They can only use the adaptations that they come up with and the adaptations they landed on the island with. Each speciation event is like a group of young islanders setting off and starting a new clan on an isolated on their own, only able to take along the adaptations that were passed on to them.

In this way, you have lineage specific adaptations which are solutions that only that lineage has. You also see those good adaptations flourish in the next generations, and then new lineage specific adaptations and modifications occuring in each of those new branches and generations. It was this type of branching and spreading out idea that solidified the idea for evolution in Darwin's mind. In fact, you can find his Eureka! moment in his own notes.

That is a nested hierarchy, and it formed the basis of the theory of evolution from the very start as written by Darwin himself.

lewiscalledhimmaster · Apr 13, 2015

Thanks to all who have participated in the learning threads, which I started on this forum. Now it's time to go back to the first thread and read and think and ponder, as well as the other ones which were relevant to the evidence which relates to Evolution.

Bye for now.
George.

AV1611VET · Apr 13, 2015

lewiscalledhimmaster said:
Bye for now.

Bye.

George95 · Apr 14, 2015

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