Re: Reverse-engineering the T. rex genome

[evelyn sobielski <koreke77@yahoo.de>]

ered organism using a consensus sequence with
> strong statistical backing will not be the same as the
> ancestral organism, but I do wonder if it would be viable,
> and how close we could come to the ancestral animal.

Not very close. From what I've seen, any consensus remaining for example in 
cytB is consensus across most amniotes (at least). Noise would be so strong 
that it would even affect the nucear genome.

But you don't need to sequence all birds. Here's a shortcut:

take the chicken genome (complete) and the human genome (complete) and wait for 
the first complete croc genome. Make consesnus between crock and chicken. 
Compare to human. Take everything out that is consensus in all thre.. The 
remainder - chicken-croc but not human consensus - is a rather good (thogh 
somewhat overstimated) approximation of what you will at best be able to 
achieve. If you want to get beyond that, you'd need for example a duck, ostrich 
and passerine genome, to weed out any homoplasies between chicken and croc.

The point is that with increasing phylogenetic distinctness the consensus 
becomes less and less until all that remains are the base positions absolutely 
crucial for function. For much of the genome, the evolutionary time that has 
passed between the "proto-avian" and "proto-tyrannosaurid" lineages' split is 
sufficient to reach that point.

Now, what *could* perhaps be done is a Neoaves-wide comparison of genomic 
structure, exon/intron distributions, karyotype etc. Especially when focusing 
on paleognath and galloanserine *plesiomorph*ies (vs neoavian and crocodile 
apomorphies), this could indeed yield some useful information regarding 
nonavian theropods.


Eike