[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: AW: Tawa hallae: everything you know about basal saurischians is wrong...
I would be extremely skeptical about such an explanation.
Lateral gene transfer is extremely poorly documented among Eukaryotes.
Moreover, that paper you cite (though I've only read the abstract), should not
be interpreted too broadly.
How confident are we that this putative "endogenous defective retrovirus" is
actually of viral origin? Retrotransposons after all resemble retroviruses, but
do not spread between species.
The abstract also notes: "Many mammalian viruses have acquired genes from their
hosts during their evolution"
It is quite possible that this human gene in this "retrovirus" was incorporated
into the genome of the virus, the virus integrates into the human genome, and
the original copy is lost, leaving only the viral copy.
No lateral gene transfer between species would have occurred.
Other possible explanations, are that the virus inserted, and then later a
transposon stuck the gene in the middle of the virus.
Further more, feathers are multi-genic traits.
The amino acid sequence is altered, many other genes (whose function I am not
sure of), act to determine the shape of the scale (here, feathers being treated
as modified scales).
Feathers, and presumably this dino fuzz, originate from follicles, which will
also require many genes to form, its not simply just weird protruding
keratinized integumentary growth.
Given the similarity in structure and shape (long regular fibers), this fuzz
presumably originates in follicles and has many genes acting to affect its
shape, your hypothesis would require many many genes to be transported by a
I think the simpler explanation is just that they were ancestral or unrelated
> evelyn sobielski <email@example.com> wrote:
> From: evelyn sobielski <firstname.lastname@example.org>
> Subject: Re: AW: Tawa hallae: everything you know about basal saurischians is
> To: email@example.com
> Date: Monday, December 14, 2009, 3:24 AM
> > > (And has anybody ever checked GenBank whether
> > "feather"
> > > genes have some sort of viral signature? A
> > "domesticated"
> > > papillomavirus or similar would explain the
> > structurally
> > > different but physiologically somehow related -
> > > integumental hyperplasies triggered by a fairly
> > simple
> > > genetic mechanism, essentially - structures
> > phylogenetically
> > > widespread among archosaurs. But its genetic
> > "footprint"
> > > would be obvious, and thus this assumption could
> > > tested.)
> > Sorry, I'm having a hard time interpreting what you
> > here.
> Like the placenta appears to have evolved by
> "domesticating" a virus (doi:10.1038/35001608).
> A papillomavirus would be a good candidate because a)
> papillomaviri are known to infect birds, b) they usually
> cause integumentary outgrowths, sometimes keratineous, and
> c) they are rarely debilitating. Infection with such a virus
> could easily turn an archosaur with a monitor lizard-like
> skin into one covered in "fuzz". Not pretty, but viable.
> But as I said, it would need to be tested. The sequence of
> "feather genes" - or rather the DNA associated with these -
> would need to be recognizably viral in origin.