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Author | Topic: Can Chromosome Counts Change? | |||||||||||||||||||||||
Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
I've run into quite a few creationists who are insistant that chromosome counts cannot change. Consequently, I decided to start this thread.
What do Kiangs: Kulans: and Onagers: have to do with chromosome counts? Each of the above species does not have a single chromosome count! Kiangs can have either 55 or 56; onagers are the same, while kulans have either 54 or 55. Most of Burchell's zebras have 44, but a few have 45. This is known as a polymorphic karyotype. Furthermore, many of what we consider distinct species in Equus demonstrate this. For example, you can mate a horse (64 chromosomes) with a Przewalski's horse (66 chromosomes), and get fertile offspring. Probably the most famous crossbreed in Equus is that between a donkey (62 chromosomes) and a horse - a mule. Most are infertile, but about one in 10,000 are fertile. The reason is that chromosomes simply hold genetic data. They can break, they can merge, and there is no issue. There becomes an issue when the *content* of their genes becomes to incompatible. Looking at our chromosomes compared to the great apes, we see the same thing. All other great apes have 24 chromosomes, while we have 23. However, our chromosome 2 looks just like two of the ape chromosomes put together Are there any creationists who think this is still somehow a problem? ------------------"Illuminant light, illuminate me." [This message has been edited by Rei, 12-16-2003] [This message has been edited by Rei, 12-17-2003]
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.7 |
Don't forget amphibians and plants for some of the most dramatic examples of chromosome counts changing.
Probably the most famous crossbreed in Equus is that between a donkey (62 chromosomes) and a horse - a mule. Most are infertile, but about one in 10,000 are fertile. Some mules are fertile? Really? What happens when you breed two mules? Do they breed true?
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Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
"Cum mula peperit" was an old Latin saying; it means "when a mule foals", and had the equivalent connotation of "once in a blue moon".
Here's some articles about a recent foal - the father was a donkey, and the mother a mule. BBC NEWS | Science/Nature | Morocco's miracle muleBBC NEWS | Science/Nature | Morocco's miracle mule 'confirmed' http://cooltech.iafrica.com/science/207652.htm This page states that there have been about 60 documented mule births in Europe, the USA, South America, North Africa, and China since 1527. Of course, the majority of cases are likely to go undocumented. All reported fertile mules have been female. I've never, however, heard of two mules breeding. [This message has been edited by Rei, 12-17-2003] [This message has been edited by Rei, 12-17-2003]
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Coragyps Member (Idle past 734 days) Posts: 5553 From: Snyder, Texas, USA Joined: |
However, our chromosome 22 looks just like two of the ape chromosomes put together
Typo - it's our chromosome 2.
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Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: Dern keyboard ------------------"Illuminant light, illuminate me."
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judge Member (Idle past 6443 days) Posts: 216 From: australia Joined: |
I've run into quite a few creationists who are insistant that chromosome counts cannot change. . Really?Are these claims made by creationist organisations or individuals? Who makes these claims? thanks
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Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
I was tempted to start this thread after hearing it one too many times from individuals; a recent talk with John Paul reminded me of that, and I figured I'd start a thread. As an example, a quick search on evcforum itself shows a poster named Ryan Bibler stating:
"I have a question for the biologists in the group. How exactly can a new species end up with a different number of chromosomes than the species from which it descended? For example, hares have 24 pairs of chromosomes, while domestic rabbits have 22 and cottontails have 21. Back when I was a creationist, I would use this discrepancy as an argument against macroevolution. I'm just curious about the mechanism of how this works, thanks. " (note: looks like most of the points that I raised here were raised there as well. Oh well ) Hmmm... looks like SPLx did the same thing over here. He cites Davidson's obsession with chromosomal change. Shoot... I thought I was posting something new That's what I get for not searching thoroughly enough first... Anyway, I'll list a few more: navajoeverclear wrote: "If evolution is gradual, why are there any distinct species? I don't see why there wouldn't be as much 'intermediate' species as 'definate' ones, if evolution is how it works. I'm not saying all evolution is wrong(or that i understand it well enough to say(thats why i'm asking)), i can definately accept natural selection, but i don't see one species changing into another. All dogs have the same amount of chromosomes--- though their appearance and general behavior varies from breeds. For there to become a new species, there must be a different number of chromosomes, is there such thing as a partial chromosome(i'm pretty sure there isn't)? If not, how does a creature suddenly gain more or less chromosomes? Back to JohnPaul, he stated earlier: "Creationists see the difference in chromosomes as a tell-tale indication primates and humans did not share a common ancestor. Primates have 48 chromosomes and humans have 46. " (etc) ------------------"Illuminant light, illuminate me." [This message has been edited by Rei, 12-17-2003]
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some_guy Inactive Member |
As I creationist I believe in chromosome changes for sure! That's where the whole "created kind" debate comes from. That animals like zebras and horses and donkeys all came from one created kind in the beginning. And so if that is true then the chromosomes must have changed because horses and zebras don't have the same amount. But there is one crucial aspect of that change that creationists believe that evolutionist's don't. The amount of chromosomes cannot increase. As in genetic information is never added, which must be true for evolution to work. Therefore with the "created kind" thinking, the very first horse kind would have had the most chromosomes. And all the variations of that kind would have the same or less chromosomes.
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crashfrog Member (Idle past 1467 days) Posts: 19762 From: Silver Spring, MD Joined: |
That animals like zebras and horses and donkeys all came from one created kind in the beginning. What test would you use to distinguish between two organisms that are decended from the same kind and two that are decended from different kinds?
Therefore with the "created kind" thinking, the very first horse kind would have had the most chromosomes. And all the variations of that kind would have the same or less chromosomes. So you'd accept processes that increase chromosome counts as evidence against your position?
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some_guy Inactive Member |
yes id like an evolutionist to prove to me that "new" genetic information can be added.
[This message has been edited by some_guy, 12-19-2003]
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Rei Member (Idle past 7013 days) Posts: 1546 From: Iowa City, IA Joined: |
quote: It happens very often. The most common cause is called polyploidy, and is common in plants; it occurs when all chromosomes double. Other cases include merging and breaking of chromosomes. For some observed instances in speciation, visit here andhere for starters. When you're ready, I'll give you more. ------------------"Illuminant light, illuminate me." [This message has been edited by Rei, 12-19-2003]
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crashfrog Member (Idle past 1467 days) Posts: 19762 From: Silver Spring, MD Joined: |
Did you miss the first question of my post? This is a question you have to answer if you want us to take the idea of "kinds" seriously.
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some_guy Inactive Member |
"[The created kind concept] proposes that a kind will consist of populations that can interbreed, while still allowing room for variation." Page not found - Apologetics Press
But there is no easy method right now (other than interbreeding all animals, which would also be a very inacurate way to go about it). There would need to be much further research into this to set up a syetem to determine the specific barriers between different created kinds. And Rej, alright maybe saying that chromosomes cannot increase is false. But generally i mean that the first created kind would have the most chromosomes and the variations after would have the same or less. Although in each of the methods of chromosome increase you mentioned, neither of them allow for "NEW" genetic information to arise.
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Rrhain Member Posts: 6351 From: San Diego, CA, USA Joined: |
some_guy responds to Rei:
quote: And the follows it up with:
quote: (*blink!*) You did not just say that, did you? Please tell me how the addition of a new chromosomes isn't a direct example of an INCREASE. If you have more chromosomes than before, how can it be anything except an increase? ------------------Rrhain WWJD? JWRTFM!
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crashfrog Member (Idle past 1467 days) Posts: 19762 From: Silver Spring, MD Joined: |
"[The created kind concept] proposes that a kind will consist of populations that can interbreed, while still allowing room for variation." So, it's a species. Then why didn't you just call it "species"? Ok, you probably didn't mean "species". But I'm sure you don't mean "populations that can interbreed" because those arise all the time. We observe populations that once could interbreed - were once even the same population - stop being able to interbreed as a result of accumulating change through mutation. It's called "speciation". How can you talk about "created kinds" if new "kinds" - under your proposed definition - arise all the time through observed processes?
There would need to be much further research into this to set up a syetem to determine the specific barriers between different created kinds. How are we supposed to do research on something that there's no evidence to suggest exists, and is contrary to observation.
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