Evolution? Good Discussion here

[bobze]

That is ok no problem at all, I understand the dreaded late night work, .

@Bobze,
Sorry about screwing up the grammar and vocabulary when speaking about Evolution, I'll try to improve upon that.

But with respect to your other points, you are right I should be more specific about what I mean when it comes to mutation.

No problem at all.

@Kglocc,
When I meant other mechanisms of variation I did not have any specific ones in mind. But I will try to look around for some examples when I get the chance.

I am also wondering where the OP is.

Kglocc brought up a great one, HERVs, a significant portion of our genomes is actually given over to these little guys. But, as I pointed out, the bulk of variation for natural selection to "chew on" comes from sex and the broad (very broad) category of mutation.

Certainly other minor sources play a role and sometimes that role is increased or decreased depending on the lineage. Prokaryotes exchange genes with each other (to the point of scary abandon) in a process we call lateral (or horizontal) gene transfer (LGT).

Eukaryotes too, have partaken in LGT through endosymbiotic relationships.

Plants seem especially prone to LGT through the auspice of viruses. And they go out of their way to hybridize (something I'd consider another source of variation) and make a real mockery of gene pools.

Epigenetics, which deals with the "state" DNA is inherited in may play a role. DNA is passed from parental cell to daughter cell in "preconfigured" states, which mostly involves the methylation of different regions of DNA. Methylation plays a key role in gene expression. While it has become very apparent over the past 10 years the importance of this in medicine, the evolutionary implications are not well understood. In theory, during gametogenesis and early embryonic gamete development, the "state" of DNA should be reset. You wouldn't want your offspring inheriting DNA in that "state" of say, a plasma cell where very few genes are "turned on".

It seems, that "resetting" the "state" may not always happen, the way it should. Which means, you potentially alter the timing or expression of genes during development. Something which could potentially have huge implications for evolution.

Anyway, the answer to your most immediate question is "yes" there is more to variation than just mutations. But as I said before, drill into your head "mutation and sex" as those are by far and away the most accountable in evolution.

P.S.
I am sorry if I have offended or angered anyone with my comments up to this point. I am still just a student so my education is constantly ongoing and I am learning as I go. I will take all your comments into account and try to improve my understanding.

We should endeavor to make learning a life long processes. One's education can never be complete. Even the great master Michelangelo had, on a sign written in his workshop, in his latter days; "Ancora Imparo". Understand that phrase like Michelangelo and you'll be alright

 

[cosmos 2.0]

Kglocc brought up a great one, HERVs, a significant portion of our genomes is actually given over to these little guys. But, as I pointed out, the bulk of variation for natural selection to "chew on" comes from sex and the broad (very broad) category of mutation.

Certainly other minor sources play a role and sometimes that role is increased or decreased depending on the lineage. Prokaryotes exchange genes with each other (to the point of scary abandon) in a process we call lateral (or horizontal) gene transfer (LGT).

Eukaryotes too, have partaken in LGT through endosymbiotic relationships.

Plants seem especially prone to LGT through the auspice of viruses. And they go out of their way to hybridize (something I'd consider another source of variation) and make a real mockery of gene pools.

Epigenetics, which deals with the "state" DNA is inherited in may play a role. DNA is passed from parental cell to daughter cell in "preconfigured" states, which mostly involves the methylation of different regions of DNA. Methylation plays a key role in gene expression. While it has become very apparent over the past 10 years the importance of this in medicine, the evolutionary implications are not well understood. In theory, during gametogenesis and early embryonic gamete development, the "state" of DNA should be reset. You wouldn't want your offspring inheriting DNA in that "state" of say, a plasma cell where very few genes are "turned on".

It seems, that "resetting" the "state" may not always happen, the way it should. Which means, you potentially alter the timing or expression of genes during development. Something which could potentially have huge implications for evolution.

Anyway, the answer to your most immediate question is "yes" there is more to variation than just mutations. But as I said before, drill into your head "mutation and sex" as those are by far and away the most accountable in evolution. :

Mutations and changes that occur over a long period of time may be useful for a particular species.
During gametogenesis especially homo sapiens the egg provides an environment for all genes to be turned on (stem cell) depending on cell differentiation .

 

[bobze]

Mutations and changes that occur over a long period of time may be useful for a particular species.
During gametogenesis especially homo sapiens the egg provides an environment for all genes to be turned on (stem cell) depending on cell differentiation .

That is, for the most part true. Of course not all genes are really turned on, rather they are set to a sort of "default state", where differentiating cell lines can access them. Something not generally possible to cells once differentiated (though such a reversion can be induced through transformations of cell lines with viral delivery systems).

The point I was making for TheEnigma, who was inquiring about other modes of variation in evolution, was that sometimes that process doesn't quite work out. Paramutations, are really epigenetic inheritances that violate Mendel's Law of assortment.

Of course, transgenerational epigenetic inheritance (the only type which could affect evolution) is seen more prominently in organisms like plants, prokaryotes and other microbes. All of which seem more than willing to take their genomes to the casino.

Obviously, transgenerational epigenetic inheritance would provide a pretty strong selective advantage for reversible phenotypes. Suppose for a moment, you had two food sources and two different genes needed to digest those sources. You turned one gene "off" when its corresponding food source wasn't present. If you could bequeath to your offspring the correct active gene as per your environment, you could them a "evolutionary leg up". Saving them time and energy costs of sorting out which gene to "activate" on their own.

Such a thing sounds pretty incredible and more akin to some kind of Lamarckian evolution. However, there is evidence to show that such a thing can happen in mammals even¹. And we've known since the 40's (maybe it was the 50's, I can't remember at the moment) that certain plant alleles can modulate the inheritance of others.

Its also been postulated that transgenerational epigenetic inheritance may play a role in protecting certain genes from mutation (at least certain types of mutations).
"[URL
There was an interesting review of epigenetic inheritance examples published back in 2009.[/URL]

You might also find interestinghttp://www.nescent.org/science/awards_summary.php?id=92" on what role epigenetic variation may play on phenotypic evolution.

1. http://www.fasebj.org/cgi/content/full/12/11/949"

Edit: I realize the first two links require a subscription, for those of you who are students and attending a college which provides you with subscription to scientific literature, then simply do an "off-campus sign-in" for your library and copy the ".proxy.schoolname.edu" into the link after the ".org" or ".edu" for access. Those of you without access, but who maybe interested--I'd invest in library card :)

 

[Mkorr]

The E. coli experiments probably refers to the E. coli long-term evolution experiment carried out by Lenski et. al.

Blount, Z. D., C. Z. Borland, and R. E. Lenski. 2008. Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli. Proceedings of the National Academy of Sciences, USA 105:7899-7906. (http://www.pnas.org/content/105/23/7899.abstract).

Barrick, J. E., D. S. Yu, S. H. Yoon, H. Jeong, T. K. Oh, D. Schneider, R. E. Lenski, and J. F. Kim. 2009. Genome evolution and adaptation in a long-term experiment with Escherichia coli. Nature 461:1243-1247. (http://www.nature.com/nature/journal/v461/n7268/full/nature08480.html).

etc.

This, along with many other examples, refutes the creationist gambit that no beneficial mutations has been observed.

 

[nismaratwork]

How on Earth has this thread gone for 3 pages when the OP simply issued a vague challenge and then retreated without comment? What IS this thread at this point anyway? This doesn't seem productive to me, so why not split into relevant threads that address a given OP instead of this crap? Someone, for the love of dog, lock the thread. :)

 

[DaveC426913]

How on Earth has this thread gone for 3 pages when the OP simply issued a vague challenge and then retreated without comment? What IS this thread at this point anyway?

Agree, the OP has fallen off the face of the Earth.

It picked up steam in post 13/14 wherein the question was asked what problems or weaknesses evolution currently suffers from.

ThE3nigma has suggested that lab tests have not shown diversity effects we might expect. Counter arguments revolve around what we should expect and what we are seeing.

Then nismaralatwork came along and wondered what the heck is going...

Wait. I'll stop there. That's pretty much where we are.

 

[Ken Natton]

Well there are a few possibilities for what happened to Dr henegar. Perhaps he / she was scared off by the strong response his / her post garnered; perhaps he / she was persuaded that his / her argument wasn’t really all that original; or perhaps the good doctor achieved exactly what he / she intended – what DaveC426913 called ‘stirring the pot’. I‘m not sure it matters – as it turns out, his / her thread title was apposite. I confess that the discussion in the later posts on this thread is well beyond my knowledge and understanding, and I think that is well to the good – I reckon that I can tell the difference between when people are posting waffle and when they are talking at a level above mine.

And yet I do have a perspective to offer to the discussion of sickle red blood cells. My understanding is that not everyone who has sickle red blood cells suffers from sickle cell anaemia. The latter is quite a rare condition, but sickle red blood cells not so rare. If I was to cite my source, it would again only be a popular science book, so perhaps you are going to question the reliability of my source. But certainly, the point is, the connection between malaria and sickle red blood cells was not discovered by the scientific investigation of the kind of technicalities explained by bobze in post #29. It was essentially a statistician who observed that the map of malarial areas around the world nearly exactly coincided with the map of areas where sickle red blood cells were prevalent. Subsequent scientific investigation has developed the kind of understanding bobze explained to us. But again, that co-incidence of where malaria threatens and where sickle red blood cells have become common among the population is in itself evidence that it does constitute human evolution – a specific response to a specific threat.

 

[cesiumfrog]

Sickle cell anemia occurs if you inherit the gene from both parents. These people have an above average mortality rate. But the people who have only one copy of the gene have a below average mortality rate for malaria afflicted areas.

 

[nismaratwork]

Agree, the OP has fallen off the face of the Earth.

It picked up steam in post 13/14 wherein the question was asked what problems or weaknesses evolution currently suffers from.

ThE3nigma has suggested that lab tests have not shown diversity effects we might expect. Counter arguments revolve around what we should expect and what we are seeing.

Then nismaralatwork came along and wondered what the heck is going...

Wait. I'll stop there. That's pretty much where we are.

Heh, thanks for bringing me up to date DaveC.

 

[DR_henegar]

You say I have fallen? I am back. College is taking my time as of now. But you know, maybe I should have a moderator lock this discussion, however, if you really wish to hear my argument, please PM me. It is stirring trouble and when it stops stirring something is going to burn. I believe this should be locked before that happens. Please, for love of science, please don't bomb me with your theories without hearing mine. >.< That is all. I wish I could lock this thread m'self but I can't.

 

[bobze]

If you've got something scientific, let's hear it...

 

[DR_henegar]

Okay, Take this into consideration. Evolution is probable. However, the thing that bothers me most is you can not teach a monkey multiple languages, nor can you have a monkey learn Parkour because of the way it walks. But, is that my argument? No. My argument is of two conflicting theories: Darwin's The theory of Evolution, and Darwin's theory of Natural Selection. If you compare and contrast what those theories imply you might see a slight kink in the chain of Evolution.

 

[DR_henegar]

I'll be back around 1:00 EST

 

[nismaratwork]

Okay, Take this into consideration. Evolution is probable. However, the thing that bothers me most is you can not teach a monkey multiple languages, nor can you have a monkey learn Parkour because of the way it walks. But, is that my argument? No. My argument is of two conflicting theories: Darwin's The theory of Evolution, and Darwin's theory of Natural Selection. If you compare and contrast what those theories imply you might see a slight kink in the chain of Evolution.

That was so incredibly stupid it's making my head hurt. You just set up a straw man, killed him yourself, then restated your "thesis". That's not support, that's tap-dancing.