Selection on Transposable Element Families

Robert Dejournett hermes at rtd.com
Thu Oct 19 00:44:35 EST 1995


In article <432cog$kcq at news.cc.utah.edu>,
David Witherspoon  <dwithers at genetics.utah.edu> wrote:
>	I am studying a family of transposable elements (TBE1s) in a 
>couple of species of ciliates (Oxytricha fallax and trifallax.)  These
>are 
>DNA "Cut and Paste" transposons.  The most striking feature of this 
>family is the degree of conservation between elements:  virtually all of 
>the several thousand elements in any given host genome are intact, 
>meaning that no stop codons, no deletions or insertions, and few 
>nonsynonymous changes (relative to synonymous changes) have 
>occurred during their divergence from each other.  I take this to be 
>evidence that some force of purifying selection has been acting on these 
>elements over a long period within the host population.

Could it be that these two species have only recenly arisen from a common
ancestor, and thus have not had time to change their genome?  About the
lack of mutations, is there no exons in the genome?  Those would tend to
mutate more I would think...

-Rob

--
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  Robert Dejournett       hermes at rtd.com     http://www.rtd.com/~hermes
"For the greatest good, for the largest number, for the longest time" G Pichot



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