Contradiction in evolution....mutations begin new species

[pippo]

Hi People,

 

OK, evolution occurs with a natural random mutation on the DNA strand. If that new specie/variation occurs timely with a change in the environmant which favors that change, that specie has an advantage. BUT, that new organism needs a mate, male/female with that same freak chance of mutation to have occured. Yes, this takes a few hundred thousand years....math takes time. Its all math, you know.

 

Still, you have biologists explaining how if a specie does not have a critical gene pool, it dies off. For example, there have been dwindling populations of say, an endangered specie. There are 24 left (whooping crane in the late 70's). Then that species gene pool is low, weak genes/inbreeding, population dies out. Then how in the jheck are those 2 mutants that find each other can advance a new specie and generate huge new successful populations???

 

Thanks!

[swansont]

You don't need for both parents to have the mutation to pass it along.

[Dan6541]

Two animals of the same species can still breed with each other when only one of them has the mutation. Their offspring gets DNA from both parents so there is a good change they will have the mutation as well.

Edited September 20, 2010 by Dan6541

[Mr Skeptic]

Hi People,

 

OK, evolution occurs with a natural random mutation on the DNA strand. If that new specie/variation occurs timely with a change in the environmant which favors that change, that specie has an advantage. BUT, that new organism needs a mate, male/female with that same freak chance of mutation to have occured. Yes, this takes a few hundred thousand years....math takes time. Its all math, you know.

 

Still, you have biologists explaining how if a specie does not have a critical gene pool, it dies off. For example, there have been dwindling populations of say, an endangered specie. There are 24 left (whooping crane in the late 70's). Then that species gene pool is low, weak genes/inbreeding, population dies out. Then how in the jheck are those 2 mutants that find each other can advance a new specie and generate huge new successful populations???

 

Thanks!

 

So you're saying that only homozygotes can survive and heterozygotes will die? That seems like an odd claim, especially considering the effect called "heterozygote advantage".

 

If you don't know the above terms, please look them up since they are basic biology. But the short of it is, we get our genes in pairs and often only one of the two is needed, so we can survive just fine with several entirely non-functional genes, and a mutant one is often no problem.

[pippo]

Thanks, people. That sure clears it up quite well for me. Its been 30 yrs since bio classes (went into Chem instead). Sure, I guess then if the mutation is dominant, it passes it on. If its recessive, no, right?

 

Still, a related point, how can the cranes multiply well as they did ? maybe its too soon to tell??

[Mr Skeptic]

Recessive traits are passed on, they are just unlikely to be expressed (only expressed when someone has two copies of it), so much that it could be dozens of generations before any individual will end up with two copies. That's why there are a lot of recessive disease genes, but hardly any dominant ones.

[Maximus Semprus Veridius]

Nope you only need one parent to have the dominant gene. They don't just suddenly change species because they have a different characteristic, although that would be pretty funny. And you've gotta remember billions of different mutations take place, the chances are actually quite high if you take into account the amount of mutations that a few are going to benefit the species in some way. We only remember the good mutations because those particular mutations are perpetuated through the species.

[Mr Skeptic]

Oh right. You could say you have one copy of your genes from your mother, one copy from your father, and about 20 new mutations.

[ScaryPirateMan]

Say the two creatures mated, only one had the mutation, they have offspring that matures and breeds again. If the creature the aforementioned offspring breeds with doesn't have the mutation as well, wouldn't there be a chance that the mutation wouldn't further spread, or couldn't it be degraded? I'm thinking in terms of skin pigmentation, eye color, hair color and texture. When people of different types mate, they have a child that is a mixture of both (black and white person get a lighter brown baby) and the other traits are up in the air. If the child mates with another white person, the darker skin will be further dilluted, same for another black person. So the mutation, in essence, could be bread back out of the species instead of spreading. Right?

 

 

[Sisyphus]

Say the two creatures mated, only one had the mutation, they have offspring that matures and breeds again. If the creature the aforementioned offspring breeds with doesn't have the mutation as well, wouldn't there be a chance that the mutation wouldn't further spread, or couldn't it be degraded? I'm thinking in terms of skin pigmentation, eye color, hair color and texture. When people of different types mate, they have a child that is a mixture of both (black and white person get a lighter brown baby) and the other traits are up in the air. If the child mates with another white person, the darker skin will be further dilluted, same for another black person. So the mutation, in essence, could be bread back out of the species instead of spreading. Right?

 

Skin tone is affected by many genes. One gene doesn't get diluted - you can have one copy of it, two copies, or none.

[ScaryPirateMan]

Skin tone is affected by many genes. One gene doesn't get diluted - you can have one copy of it, two copies, or none.

 

 

Hmm... interesting. So is it safe to assume then that no matter what, if, over time, a species is to survive, and a certain genetic trait is no longer visible (let's just make it easy for me and go with eye color) then later on down the road, if somehow the genes come together again, you can have a blue eyed freak? No matter how vast the time scale?

[Sisyphus]

Hmm... interesting. So is it safe to assume then that no matter what, if, over time, a species is to survive, and a certain genetic trait is no longer visible (let's just make it easy for me and go with eye color) then later on down the road, if somehow the genes come together again, you can have a blue eyed freak? No matter how vast the time scale?

 

Well, it could disappear completely. It just wouldn't gradually fade away. But yeah, a rare recessive gene could be dormant for a very long time, getting passed down and spread out but never expressed. A carrier of one copy of a gene has a 50% chance of passing it on to his children. If both parents are carriers, then there is a 25% chance that they will both pass it on, at which point the child will have two copies and it will finally be expressed.

[ScaryPirateMan]

Well, it could disappear completely. It just wouldn't gradually fade away. But yeah, a rare recessive gene could be dormant for a very long time, getting passed down and spread out but never expressed. A carrier of one copy of a gene has a 50% chance of passing it on to his children. If both parents are carriers, then there is a 25% chance that they will both pass it on, at which point the child will have two copies and it will finally be expressed.

 

 

So if it doesn't gradually fade, how then, does it disappear? It's either passed or not?

[lemur]

I would guess that most evolution takes place as arbitrary changes among a large population over a long period of time. A certain mutation probably spreads through countless migrations and interbreedings among herds without ever really making a difference one way or the other. If it is somehow a timebomb, the species could go extinct at some later moment when environmental stresses put the species to the test. Otherwise, species probably usually just go on surviving despite random deaths of large segments of the population. Then, whatever morphological changes are noteworthy through time, scientists scrutinize those to theorize a relationship between the visible morphological change and whatever conditions stressed the species to near extinction at some point. But I'm guessing most species would change morphologically through time whether or not those changes were particularly beneficial to the survival of individuals. It's just that Darwinists look for meaning in genetically determined traits; not necessarily that organisms without the new features died off without reproducing. They may have just interbred with others that had it and assimilated to the mutants.

[Sisyphus]

So if it doesn't gradually fade, how then, does it disappear? It's either passed or not?

 

Correct.

[Ringer]

OK, evolution occurs with a natural random mutation on the DNA strand. If that new specie/variation occurs timely with a change in the environmant which favors that change, that specie has an advantage. BUT, that new organism needs a mate, male/female with that same freak chance of mutation to have occured. Yes, this takes a few hundred thousand years....math takes time. Its all math, you know.

Mutations aren't only way speciation occurs. Allopatric speciation occur much more often than random mutation as far as I'm aware. Even mutations aren't necessarily something so large as to cause some sort of problem with gamete fertilization. A mutation could be something as simple as different color that helps a certain population as a whole.

 

Still, you have biologists explaining how if a specie does not have a critical gene pool, it dies off. For example, there have been dwindling populations of say, an endangered specie. There are 24 left (whooping crane in the late 70's). Then that species gene pool is low, weak genes/inbreeding, population dies out. Then how in the jheck are those 2 mutants that find each other can advance a new specie and generate huge new successful populations???

There is no gene pool without a population, the gene pool is the cumulative gene of a population. Also, there is a major difference between a population and a species, evolution acts upon populations of a species not the species as a whole. And inbreeding doesn't negatively affect many species (such as house cats).

[ScaryPirateMan]

So what is the likelyhood that something will evolve with traits that aren't necessarily useful or detrimental. Like bipedalism. I mean, human arms aren't long enough to pick fruits from a lot of trees, especially when we were to have evolved. They aren't strong enough to swing through trees like simians. I guess you could say the use of more complicated tools could have been a reason, but even so, we could have done without it. Why did we develope balance to the degree we have without the need to walk on our knuckles or have a tail? All I'm really asking here is what is the likelyhood that something could evolve with traits that really provide no benefit?

[Moontanman]

it would appear that blue eyes appeared quite recently in our history.

 

http://www.sciencedaily.com/releases/2008/01/080130170343.htm

 

 

Blue-Eyed Humans Have A Single, Common Ancestor

ScienceDaily (Jan. 31, 2008) — New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today.

 

This is a good example of how a mutation can slowly build in a population, if blue eyes was connected with reproduction in some way then blue eyes might have resulted in a new species of human...

[Sisyphus]

So what is the likelyhood that something will evolve with traits that aren't necessarily useful or detrimental. Like bipedalism. I mean, human arms aren't long enough to pick fruits from a lot of trees, especially when we were to have evolved. They aren't strong enough to swing through trees like simians. I guess you could say the use of more complicated tools could have been a reason, but even so, we could have done without it. Why did we develope balance to the degree we have without the need to walk on our knuckles or have a tail? All I'm really asking here is what is the likelyhood that something could evolve with traits that really provide no benefit?

 

Bipedalism wouldn't have evolved if there hadn't been benefit all along the way.

 

http://en.wikipedia.org/wiki/Bipedalism#Evolution

 

In the future, you shouldn't make assumptions like that. Just because you don't know how something evolved, doesn't mean there wasn't a good reason.

 

That said, there is going to be random genetic drift that doesn't necessarily provide much benefit, especially in small populations. Just probably not a fundamental change like basic locomotion.

[ScaryPirateMan]

Bipedalism wouldn't have evolved if there hadn't been benefit all along the way.

 

http://en.wikipedia....alism#Evolution

 

In the future, you shouldn't make assumptions like that. Just because you don't know how something evolved, doesn't mean there wasn't a good reason.

 

That said, there is going to be random genetic drift that doesn't necessarily provide much benefit, especially in small populations. Just probably not a fundamental change like basic locomotion.

 

 

I was watching a documentary on the Discovery Channel a few months back (i'll locate the title for you when I can) that was discussing the "missing link" in the evolutionary chain of humans and bipedalism was one of their main concerns. I need to find the documentary so I can give more informed statements, so for that I apologize, but I wasn't just making assumptions.

[Sisyphus]

I was watching a documentary on the Discovery Channel a few months back (i'll locate the title for you when I can) that was discussing the "missing link" in the evolutionary chain of humans and bipedalism was one of their main concerns. I need to find the documentary so I can give more informed statements, so for that I apologize, but I wasn't just making assumptions.

 

Right. But a "missing link" is not knowing how something happened. From there, the bad assumption is that it happened for no particular reason.

[pippo]

Mutations aren't only way speciation occurs. Allopatric speciation occur much more often than random mutation as far as I'm aware. Even mutations aren't necessarily something so large as to cause some sort of problem with gamete fertilization. A mutation could be something as simple as different color that helps a certain population as a whole.

 

There is no gene pool without a population, the gene pool is the cumulative gene of a population. Also, there is a major difference between a population and a species, evolution acts upon populations of a species not the species as a whole. And inbreeding doesn't negatively affect many species (such as house cats).

 

Thanks for the reply. No gene pool? So, wheres the line one draws for a population too small for a gene pool and one that is large "enough"? 24 cranes are too small but say, 200 cranes are about right?

 

I didnt know that about cats. Man, how are they immune (pun?) from inbreeding? recessive genes for diseases become pronounced when inbreed, I understood ..........

[Ringer]

there isn't a population to small for a gene pool, unless of course it's >2 for a sexual reproducing species. A population is just an animals species within an area capable of reproducing, the gene pool is the differences of genes within that population, so 24 cranes still has a somewhat substantial gene pool.

 

As for the inbreeding, there are quite a few animals that inbreed without much damage (i.e. cats, wasps, ants, a lot of plants and weeds, etc.) to their genetic line. Even humans can mate with their families without a very large chance of genetic deficiency so long as it isn't a direct sibling or parent. I'm not real sure on the specifics but this website has a pretty thorough explanation of inbreeding.

[pippo]

Thanks, Ringer. I did look at the site, and read it. I agree with most of it, but he goes on to remind us of historical personalities that married their first cousin, royalty, etc. Of course, one can consider it a benefit to inbreed if one 's goal is to accentuate a trait- fatter breast meat in chickens, or silkier , thicker pelts in mink, etc, BUT there is no way you can deny that while yes, you have a greater chance of obtaining that trait in the next progeny, you will increase the risk for recessive /hidden trraits that will present itself with the offspring. This is risky business, any way you cut it.

 

Thats why breeders commonly introduce "fresh blood" into their herd periodically, despite them knowing it will "dilute" their traits they have been working hard for years to conserve. Not to over do this small animnal breeding thing, but, some breeders accept their much lower survival rate in their yearly production and even boast of it, emphasising instead their "purer line" of that breed stock. Its all what one is aiming for......

Edited September 26, 2010 by pippo