dvunkannon
Posts: 1377 Joined: June 2008
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Quote (Steverino @ Mar. 24 2011,08:27) | Gerneal question I was sent in response to humam chromosome 2:
Quote | Honestly ... is there any similar two species ... with the same 99% gene relation such as the man-chimp ... with one having a combined chromosomes 6 or 8 or whatever ... there must be evidence that combination of chromosomes can lead to evolutionary speciation. Because as far what I know; combining genes results to two things only. |
Anyone? |
I agree with OgreMkV, with the caveat that you can see the possible fusion site at the "banding of the chromosome" level of analysis, you don't need fully sequenced genomes. Then sequence just the apparent fusion site and look for the mirrored telomere sequences.
There was a recent UD post on "interstitial telomeric sequences". Googling that phrase, "Robertsonian translocation", and "chromosome fusion" got some interesting hits.
Some assert that fusion is common. Maybe it is.
Robertsonian translocation seems to happen frequently in humans, 1 of 1000 live births. While the chimp 2a and 2b chromosomes look like candidates for Robertsonian translocation due to their long/short arms, the fusion that separates humans from chimps is not Robertsonian, because the short arms survived the fusion. However, your correspondent may be lumping the categories together as evidenced by the last sentence.
The point of the UD post was that there are a lot of ITS sites inside the human genome. A good number are associated with inversions, which makes sense. If the end of a chromosome breaks off, flips around and reattaches, you get an inversion with associated ITS, assuming the end gets a new telomere and you survive. That is not completely relevant to the situation at the fusion site, which has a mirrored ITS.
Bottom line: the fusion of 2a and 2b preserved all genetic material. Other common fusion types, such as Robertsonian translocation, do not. Humans rarely mate with close relatives. Other primates may, given their close social groups. So a need to "marry your sister" to make a fusion event viable is not insurmountable.
-------------- I’m referring to evolution, not changes in allele frequencies. - Cornelius Hunter
I’m not an evolutionist, I’m a change in allele frequentist! - Nakashima
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