From: Preston Garrison (garrisonp@uthscsa.edu)
Date: Thu Apr 03 2003 - 00:36:14 EST
Snip...
>
>J:
>>-Elaborating on the question I am raising, this may indicate the
>>range of hosts for a particular virus infection instead of an
>>evolutionary relationship. The question is, are there any other
>>ways to interpret the data in general. I am trying to think of
>>other considerations.
>
>>
>>Consider the following from Sverdlov, "Retroviruses and Primate
>>Evolution" Bioessays 22:161-171:
>>
>>"..since retroviruses can cause cross-species infections, and there
>>are data suggesting multiple ancient cross-species transmissions of
>>retroviruses in primates."
>>Referenced articles: j. virol 1995 69:7877-7887, virology 1997 238 212-220.
>>
>>
>>Additionally, since viruses mutate much more rapidly when not
>>incorporated into a host, it is possible that events of viral
>>incoporation in gametes occur within the same wave of "retroviral
>>plague" if you will, and that the resulting incorporations would
>>look different due to the differences in rapidly mutating viral
>>strains being incorporated, not their divergence due to evolution
>>after integration (at the same time alot of the mutations observed
>>seem to compromise viral function....)
>
>P:
>This still doesn't account for the insertions being in the exact
>same site. Retroviruses just don't have the absolute site
>specificity that it would take to hit the same place twice with 3 x
>10^9 places to chose from. Another point is that other insertion
>elements that show this same phenomenon of being in the same place
>in different species, retrotransposons like L1 and Alu, have no
>extracellular transmissible form. There are no cross-species
>epidemics of L1s or Alus because they have no packaged, secreted
>form like viruses do. But there are thousands of sites where they
>have been inserted at the same position in related species.
>
P:
On my last point on the usefulness of retrotransposons for this
argument, there is a nice review next to the review Josh noted above:
SINE insertions: powerful tools for molecular systematics
Andrew M. Shedlock1,2 and Norihiro Okada1*
BioEssays 22:148-160, 2000
Of course, the people working on these things aren't interested in
proving common descent. They assume that was proven long ago.
Preston G.
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