[Taxacom] ancestor DNA (was...)

[Doug Yanega]

Sergio Vargas wrote:

>  > ...Never heard of Ancient DNA yet or dinosaur amino acid sequences?
>>  We have now genetic information of ancestors, isn't that great!
>
>I don't think one could call a fossil's DNA "ancestor DNA"... it
>should be called extinct taxon DNA... fossils are not ancestors, are
>just extinct taxa.

I'm not sure I follow any of this; it's my understanding that - in 
certain groups of organisms (mostly plants, but I'm sure there are 
animals in this category) - we KNOW that one extant species is the 
ancestor of another species (e.g., through polyploidy). Surely, 
someone, somewhere, has run a phylogenetic analysis that includes at 
least one such pair of species. And just as surely, they would come 
out as sister taxa. A phylogenetic analysis - by definition - will 
always resolve taxa into terminal positions if there is even a single 
character in the matrix which differs. If one of those genuine 
ancestral taxa went extinct (and therefore became a "fossil"), that 
would not change its position on the cladogram. While it seems 
unlikely that any particular fossil species is the direct ancestor of 
any extant species, it is not *impossible* (in fact, the odds would 
go up as the fossil becomes younger). What is probably impossible is 
ever *proving* that a fossil taxon is the ancestor of some living 
taxon.

Sincerely,
-- 

Doug Yanega        Dept. of Entomology         Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314        skype: dyanega
phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82