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# of chromosomes parallels evolution?

Francois JEANMOUGIN pingouin at crystal.u-strasbg.fr
Thu Feb 13 02:15:04 EST 1997

In article <5dto1c$qce at ns1-1.cc.lehigh.edu>,
	mll6 at Lehigh.EDU writes:
>Someone asked in sci.bio.evolution, how evolution can produce species with a #
>of chromsomes that differ from the parent species.   I was wondering if
>the # of chromosomes per species tends to change in parallel with speciation,
>and what the relationship tends to be in general ( I assume each new
>speciation doesn't automatically indicate a change in the # of chromosomes).
>I know that if chromosomes are linked-gene clusters, then selection should
>favor the producing of chromosomes containing genes that are adaptive in net,
>but I'm wondering what would cause a new chromosome to form
>(towards the end of becoming another net adaptive cluster of genes)?
>Can the new creation be spontaneous (and under what conditions?), or does it
>have to be derived from a pre-existing chromosome (by splitting)?

'don't know if this will help, but there was an article on linguistic
analysis of yeast chromosome III, and it seems that right hand could be
a duplication of left hand of the same chromosome, very early in evolution.
(the period of Y/R rich regions are similar, but one from telomere to
centromere, and the other from centromer to telomere).

	Also note, that part of evolution is due to duplication of a gene and
then modification of the fonction. If you think that telomere studies and
chromatin organisation let us think that there is a maximal size for a 
chromosom, linked to its telomere stability, you can try to construct
the succession of evenments that lead to the formation of a new

	I just want to point that in evolution, ALL evenments are
involved, not only one. Apologize for my (so called) english,

Francois Jeanmougin
Service de bioinformatique / bioinformatics service
IGBMC BP 163 67404 Illkirch France
tel :(France) 03 88 65 32 71 / (international) (+33) 3 88 65 32 71
e-mail : jeanmougin at igbmc.u-strasbg.fr
"C'est pas parcequ'on monte au banc, qu'il faut descendre a jeun." (Thiefaine)

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