Isolation, Adaptation and Proving Evolution

[PsychoticEpisode]

Just some personal ramblings. Thoughts I've been harboring for a while.

I may be wrong but it appears to me that evolution works best if the subject or animal becomes isolated from its previous normal habitat. Whether it be acts of nature, continental drift or some other cataclysmic event there seems to be some evidence that isolation forces or allows for adaptation. I'm just thinking about ourselves and how different races may have evolved because of isolation. Everytime I think of this I can't help wondering about those swimming iguanas in the Galapagos. But then again I can think of living fossils such as the coelecanth or Wollemi Pine that haven't changed over millions of years.

If somehow in our future man begins to explore the far reaches of the universe and then settles on unknown worlds becoming isolated I have to believe, given time , that changes will occur to promote survival. If stuff like this could only be observed.

That would mean we would have to travel at near light speeds and this brings me to another idea I had. Assuming Einstein is right, would it not be possible to prove evolution without going anywhere. He'd have to have been a little wrong too. People leaving and then returning to Earth at near light speeds should see a planet that has advanced far into the future. Getting back to tell everybody what they found could be a problem but for those adventurers there would be first hand knowledge that changes did or didn't take place. Well at least a few people would know. Suppose they could return to their own past with the evidence. I holding out hope that somehow evolution can be proven 100% thereby silencing its many detractors. What a great day for science that would be.

 

[CharonZ]

You are talking about two different things here. But before I start I should mention again that evolution is not targeted at something. So there is no evolution towards anything, and surely not towards better adaptation. This may become clearer in the following example.

First evolution. As I said in other threads already, evolution merely means that the allels in a population (that is the gene variants in a single place, or locus on the chromosome) change. Assume three different allels a, b, c. In a starting population there is, say 50% a, 20% b, 10% c. Now let's futher assume that for one reason or another the distribution changes. Let's say that individuals with allel a are more susceptible to a certain poison that enters the population and c less. Now, many generations later under this selective pressure the distribution could be 20% a, 20% b and 60% c. This is evolution already without that new phenotypes arise. That is, no new traits were developed

Now to seperation of populations. What you are talking about here is a special event during evolution, namely speciation. This is the process during which a new species arises. Isolation, together with genetic drift can together lead to the rise of a new species, but it is only part of evolutionary processes. Furthermore the size of a population can affect the speed of evolution, but again, it does not necessarily mean a better adaptation.

Assume again a population with 50% a, 20% b and 30% c. Further assume that it is a very large population. In this case changes in allel distribution as in the above example can easily be reverted, once the selective pressure ceases (e.g. if the poison vanishes).

Now assume that out of the large population, a very small one gets isolated for some reason. let's say 10 individuals with the above allel distribution. That makes 5 individuals with a, 2 with b and 3 with c. Now let's also take genetic drift into account. By a purely randome reason (not connected to the allels in question), say, a rockslide, both b bearers die. In the large population this wouldn't have an effect, but in the small one it leads to a complete extinction of allel b. This leads to a drastic change (fast evolution) in the allel distribution: change to 63% a, 0% c and 37% c in a single generation. Now due to the different starting allel distribution, different ecological niches and thus selective pressures and so on, this population might deviate from the main population from which it was separated and together with mutations and (in case of e.g. microorganisms and plants) gene flux, gradually a new species might arise that due to its slightly different genetic make-up cannot bread with the original population anymore.
This model btw. is the reason of the punctuated equilibrium theory proposed by gould, in which on the fringes of large populations or isolated pockets of them seem to undergo sudden and fast speciation evolutionary events (such as speciation).

Just another point, you told about "races". As everything below the species taxon is not really a hard scientific unit, I'd stick to "species". Races are possibly an useful units for breeders but as such are not a true phylogenetic unit.

 

[valich]

You are talking about two different things here. But before I start I should mention again that evolution is not targeted at something. So there is no evolution towards anything, and surely not towards better adaptation.

As Darwin and Wallace have shown, evolution is geared toward the survival of the fittest through natural selection. When changes in the environment occur that lead to the detriment of certain traits or characteristics of a species, the beneficial mutated traits accumulate and lead toward that species' survival. Evolution leads towards an accumulation of beneficial traits in the population that allows the species to adapt to its changing environment: basic fact of evolution. The target is survival. The underlying force is thermodynamics.

 

[valich]

. Everytime I think of this I can't help wondering about those swimming iguanas in the Galapagos. But then again I can think of living fossils such as the coelecanth or Wollemi Pine that haven't changed over millions of years.

If somehow in our future man begins to explore the far reaches of the universe and then settles on unknown worlds becoming isolated I have to believe, given time , that changes will occur to promote survival. If stuff like this could only be observed.

That would mean we would have to travel at near light speeds and this brings me to another idea I had. Assuming Einstein is right, would it not be possible to prove evolution without going anywhere. He'd have to have been a little wrong too. People leaving and then returning to Earth at near light speeds should see a planet that has advanced far into the future. Getting back to tell everybody what they found could be a problem but for those adventurers there would be first hand knowledge that changes did or didn't take place. Well at least a few people would know. Suppose they could return to their own past with the evidence. I holding out hope that somehow evolution can be proven 100% thereby silencing its many detractors. What a great day for science that would be.

You are really rambling quite a bit here. When you think about the Galapogas, in terms of evolution, you should not be thinking about the swimming iquanas and sea turtles, you should be thinking about how Darwin discovered how Finchs adapted through acquiring traits to feed on the different variety of food on each island: evolving into birds with long or short beaks, thick or thin.

But then you go on to introduce Einstein and the travel of humans at the speed of light. So you're going from science to science fiction, like on Star Track.

 

[CharonZ]

Evolution leads towards an accumulation of beneficial traits in the population that allows the species to adapt to its changing environment: basic fact of evolution. The target is survival. The underlying force is thermodynamics.

Wrong and wrong again (why oh why do I bother). Natural selections and the resulting selective pressure lead to an accumulation of beneficial traits, but only for the given selective pressure. Evolution itself only leads to undirected changes. Furthermore, there is no adaptation to a changing environment per se. Only a large (unadapted) gene-pool could be seen as a reservoir for adaptation to constant changes.

 

[spidergoat]

That's true, isolation- wether geographic or cultural, often drives the evolution of new species. A great example is those little people they found in Indonesia.

It's possible that the rapid recent evolution of humans only happened after we left our forest environment for the plains. Animals tend to keep their food sources limited to avoid mutagens. When they can't, and branch out to eat many different things, the possibility of greater mutation occurs.

 

[superluminal]

CharonZ,

I agree with you fully. And you bother because you care.

 

[valich]

Wrong and wrong again (why oh why do I bother). Natural selections and the resulting selective pressure lead to an accumulation of beneficial traits, but only for the given selective pressure. Evolution itself only leads to undirected changes. Furthermore, there is no adaptation to a changing environment per se. Only a large (unadapted) gene-pool could be seen as a reservoir for adaptation to constant changes.

You sound like a broken record: "wrong, wrong, blah, blah, wrong."

Please define: "given selective pressure"?

Fact: Organisms evolve by random chance mutations of gene alleles.
Fact: Some of these mutations are deleterious, some are neutral, others are advantageous, i.e, they allow the species a greater degree of fitness to its environment.
Fact: Both the genotype and the resulting phenotype can be considered as advantageous, neutral, or disadvantage depending upon that degree of fitness.
Fact: Beneficial traits are more likely to lead to an organism's survival than deleterious traits, and thus will allow it a greater chance to reproduce and pass on those advantageous alleles.
Fact: These advantageous alleles eventually accumulate in the organism's population and allow the population a better chance of survival during environmental shifts.

The basic underlying uni-directional force in evolution, RNA replication, and protein folding, down to the molecular level is thermodynamics: fitness resulting in a more equitable distribution of various structures and an increase in entropy in the open-ended system.

Yes, you are correct: "there is no adaptation to a changing environment per se. Only a large (unadapted) gene-pool could be seen as a reservoir for adaptation to constant change." The environment does not create an adaptation, organisms evolve an adaptation that may or not be suitable to the environment, and yes only a large gene-pool can be seen and used as a source of change: that's why I use the word "population," as opposed to "individual" organism?!

Geez! Why do "I" even bother! Do you know what thermodynamics is? Have you ever heard of "equilibrium," "entropy," or "stable states"? Do you know what errors in transcription are? Do you know what allele fixation and genetic polymorphism is?