Re: Final Solution of the Aquatic Question


"Pauline M Ross" <pmross@xxxxxxxxxxxxxxxxxxx> wrote in message
news:k3tue15nscb9296927vp128c3vrsblbl5h@xxxxxxxxxx
> On Sun, 31 Jul 2005 16:07:48 GMT, "Rick Wagler" <taxidea3@xxxxxxx>
> wrote:
>
>>I think
>>this Baboon marker virus thing can be put to
>>rest.
>
> Try this one:
>
> PLoS Biol. 2005 Apr;3(4):e110. Epub 2005 Mar 1.
> Lineage-specific expansions of retroviral insertions within the
> genomes of African great apes but not humans and orangutans.
>
> Yohn CT, Jiang Z, McGrath SD, Hayden KE, Khaitovich P, Johnson ME,
> Eichler MY, McPherson JD, Zhao S, Paabo S, Eichler EE.
>
> Department of Genetics, Case Western Reserve University,
> Cleveland, Ohio, USA.
>
> Retroviral infections of the germline have the potential to
> episodically alter gene function and genome structure during the
> course of evolution. Horizontal transmissions between species have
> been proposed, but little evidence exists for such events in the
> human/great ape lineage of evolution. Based on analysis of finished
> BAC chimpanzee genome sequence, we characterize a retroviral element
> (Pan troglodytes endogenous retrovirus 1 [PTERV1]) that has become
> integrated in the germline of African great ape and Old World monkey
> species but is absent from humans and Asian ape genomes. We
> unambiguously map 287 retroviral integration sites and determine that
> approximately 95.8% of the insertions occur at non-orthologous regions
> between closely related species. Phylogenetic analysis of the
> endogenous retrovirus reveals that the gorilla and chimpanzee elements
> share a monophyletic origin with a subset of the Old World monkey
> retroviral elements, but that the average sequence divergence exceeds
> neutral expectation for a strictly nuclear inherited DNA molecule.
> Within the chimpanzee, there is a significant integration bias against
> genes, with only 14 of these insertions mapping within intronic
> regions. Six out of ten of these genes, for which there are expression
> data, show significant differences in transcript expression between
> human and chimpanzee. Our data are consistent with a retroviral
> infection that bombarded the genomes of chimpanzees and gorillas
> independently and concurrently, 3-4 million years ago. We speculate on
> the potential impact of such recent events on the evolution of humans
> and great apes.
>
> --
> Pauline Ross
>
Thanks for flagging this. It is an interesting read but
Marc's preferred scenario is far from the only one
indicated. Firstly taking the data at face value means
that primate phylogeny has to be reworked to produce
a human-orang-gibbon clade versus a gorilla-chimp-
Old World (Cercopithecid) monkey clade and this just
conflicts with too much other data to be realistic. The
argument for the line leading to Homo abandoning Africa
3-4 million years ago and then re-entering while not impossible
has absolutely no fossil evidence to back it up. Much more
promising, IMHO, are the arguments concerning major
changes in population structure. We know that the tropical
rain forest in Africa became severely reduced at various
times in the Pleistocene and this would have a dramatic
effect on the populations of forest apes. At 3 to 4 million
years ago chimps and, to a lesser extent, gorillas would have
been in direct competition with various species of australopithecines.
Since a'piths seem to have preferred fairly heavy cover- the
forest margins if you will - this could have had the effect of
partitioning the populations of forest apes into isolated forest
refugia and creating small populations where these retroviruses
could become fixed in their genomes

In any event this is fascinationg stuff and we will have to
see where it leads. The authors don't seem to like the
alternative primate phylogeny oor human ancestral
abandonment of Africa very much and one can anticiapte
a lively debate. MV, if he remains true to form, will be
waving this around as some kind of done deal that
supports the most extreme and unlikely scenario possible.

Again, thanks for flagging this.

Rick Wagler


.

Relevant Pages

  • Re: Final Solution of the Aquatic Question
    ... Lineage-specific expansions of retroviral insertions within the genomes of African great apes but not humans and orangutans. ... endogenous retrovirus reveals that the gorilla and chimpanzee elements ...
    (sci.anthropology.paleo)
  • Re: Final Solution of the Aquatic Question
    ... genomes of African great apes but not humans and orangutans. ... human/great ape lineage of evolution. ... BAC chimpanzee genome sequence, ... endogenous retrovirus reveals that the gorilla and chimpanzee elements ...
    (sci.anthropology.paleo)
  • Re: Final Solution of the Aquatic Question
    ... > genomes of African great apes but not humans and orangutans. ... > human/great ape lineage of evolution. ... > endogenous retrovirus reveals that the gorilla and chimpanzee elements ...
    (sci.anthropology.paleo)