Can Chromosome Counts Change?

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 togetherAre 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]

"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 mule
BBC NEWS | Science/Nature | Morocco's miracle mule 'confirmed'
http://cooltech.iafrica.com/science/207652.htmThis 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]

quote:

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However, our chromosome 22 looks just like two of the ape chromosomes put together

Typo - it's our chromosome 2.

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Dern keyboard ------------------
"Illuminant light,
illuminate me."

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]

quote:

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The amount of chromosomes cannot increase.

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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]