Merging of chromosomes

[Zylstra]

So, examination of the genetic code has revealed that the reason our species seems to be short a chromosome is because two smaller ones have merged together, while they remained separate in related species. Now my questions are these:

- Would a human whose genes were separate (yet contained the same information) be able to successfully breed with other humans whose genetic structure resembles the current form?
--- if yes, then what advantage might the merging of these chromosomes have had, or is genetic drift believed responsible for it becoming the 'standard' for AMH?
---If no, then how could this mutation have arisen, if any offspring born with these chromosomes fused would only be able to breed with eachother?

I don't see how such a mutation could survive if it leads top speciation/ the inability to breed with 'non-mutants'. How does the current model/theory of human evolution explain this? It seems to my mind top be the biggest hurdle regarding an evolutionary development of Man (something I'm surprised creationists don't latch onto). Though I know it would be arguing out of ignorance to cite this as meaning evolution couldn't happen, it's been troubling me for some time now.



I hope I made the question clear enough :/

 

[Netheralian]

Would love to give an answer here, but as I don't have a clue I can't! I also have had this question at the back of my mind for sometime and have no doubts that it is answerable by one of the evo-biologists around here and don't really see it as the hurdle that you suggest it is...

If I may expand on your question a little?

How/why do chromosomes change/merge? I would assume that the mutation causing this isn't a spontaneous one as then it would seem to me that there would be an incompatibility of individuals with population - i.e. a horse trying to breed with a donkey for example. OK, maybe bad example but we know these two species can successfully interbreed - although it always(?) results in a sterile offspring due to the different number of chromosomes. Or is it more than just the chromosome mismatch that causes the sterility? If they don't merge spontaneously however, how do you have a partial merge of two chromosomes?

 

[SchrodingersFinch]

- Would a human whose genes were separate (yet contained the same information) be able to successfully breed with other humans whose genetic structure resembles the current form?

Do you mean "a human whose chromosomes were separate"?

I don't think the chromosomal fusion affected breeding significantly, since the probability of the same chromosomal fusion occurring in two individuals seems very small. There are several cases where chromosomal fusion had no negative effect on fertility. (see: http://pandasthumb.org/archives/2009/02/the-rise-of-hum-1.html)

--- if yes, then what advantage might the merging of these chromosomes have had, or is genetic drift believed responsible for it becoming the 'standard' for AMH?

I don't know. But even if it was completely neutral it could have spread throughout the population during a genetic bottleneck.

Here's some further reading:
http://scienceblogs.com/pharyngula/2006/09/luskins_ludicrous_genetics.php
http://pandasthumb.org/archives/2009/02/the-rise-of-hum.html

 

[Zylstra]

Do you mean "a human whose chromosomes were separate"?

yes ops

Thanks for the links. To make sure I'm understanding correctly, basically very similar mutations have been seeing goats and mice, and they faced no such reproductive barrier? Are you aware of any lab experiments involving artificially merging (if a way can be found) the chromosomes of mice germ cells prior to fertilization?

 

[SchrodingersFinch]

Thanks for the links. To make sure I'm understanding correctly, basically very similar mutations have been seeing goats and mice, and they faced no such reproductive barrier? Are you aware of any lab experiments involving artificially merging (if a way can be found) the chromosomes of mice germ cells prior to fertilization?

Yes, that's right.
I haven't heard of anyone merging chromosomes artificially, and don't even know if it's yet possible.

 

[ZPrime]

So, examination of the genetic code has revealed that the reason our species seems to be short a chromosome is because two smaller ones have merged together, while they remained separate in related species. Now my questions are these:

- Would a human whose genes were separate (yet contained the same information) be able to successfully breed with other humans whose genetic structure resembles the current form?
--- if yes, then what advantage might the merging of these chromosomes have had, or is genetic drift believed responsible for it becoming the 'standard' for AMH?
---If no, then how could this mutation have arisen, if any offspring born with these chromosomes fused would only be able to breed with eachother?

I don't see how such a mutation could survive if it leads top speciation/ the inability to breed with 'non-mutants'. How does the current model/theory of human evolution explain this? It seems to my mind top be the biggest hurdle regarding an evolutionary development of Man (something I'm surprised creationists don't latch onto). Though I know it would be arguing out of ignorance to cite this as meaning evolution couldn't happen, it's been troubling me for some time now.



I hope I made the question clear enough :/

I've been thinking this question myself for a long time, and now here is a guess that has no evidence to back it on how it is might possible for there to be a emergence of species that is impossible to reproduce with its parents, yet be able to go on and produce offspring

now remember I have no back ground in biology other than high school and you tube.

if you had a population of apes, where there was a viral infection occurring it is possible for the virus to mutate inside one of the females, this mutation would have to change the virus in such a way that it would merge the 2 chromosomes. now if this was a long term virus that lived with a female host its whole life, and was able to infect the zygote that female was caring, (without killing either the host or the zygote) then the zygote could possibly have 2 less chromosomes than the parents because the virus had merged two together from both sets of dna, so from here if the same infected parent produces more than at least 2 children of different sex, than its possible for inbreeding to carry the new specie forwards ....... but I've got nothing to support that ..... at all!

but that's my best guess

in summery
virus that effects offspring to have less chromosomes but not fatal
host produces multiple offspring
offspring engage in incest, new species in formed

but i hope someone comes along who knows something about this subject and can tell us what the evidence tells us what really happend, cause i'd really like to know

 

[ZPrime]

also there seems to be a link between chromosome #2 and inteligence, this might be why the offspring where successful

 

[Zylstra]

also there seems to be a link between chromosome #2 and inteligence,

clarify