[Taxacom] Molecular vs. morphological evidence

Kenneth Kinman kennethkinman at webtv.net
Tue Jun 30 21:41:54 CDT 2009


Dear All,
     I was just watching tonight's NOVA (Science Now), and their story
on the investigation of the case of weaponized anthrax which was sent
through several letters in late 2001.  Although the ultimate solution
was molecular sequencing (and just a single base difference), a critical
step in solving the case was based on morphology of the colonies of
anthrax.  
      I think this is also probably typical of what one should expect in
taxonomic research in general.  Both molecular and morphological data
have their place, and a combination of both is far more valuable that
either type alone.  Think of it as "informational synergy".  
       However, I still believe that molecular data will increasingly
trump morphological data in the future in an increasingly greater
percentage of cases as we better understand molecular data and can
therefore avoid the pitfalls of molecular homoplasy (which will also
uncover morphological homoplasies as well).  Not that morphology will
ever be completely supplanted by molecular data (too much of the
molecular data has been lost due to extinction).  What is needed is an
increasing amount of collaboration between morphologists and
molecularists to produce maximal taxonomies that avoid the pitfalls of
either approach alone.    
      With respect to great apes, whole genomes should shed light on the
morphological similarities that have now been listed for orangutans and
humans.  Whether they are synapomorphies or plesiomorphies will (in my
opinion) be demonstrated by any number of different genomic elements
(like SINES or LINES) which show an overwhelming phylogenetic pattern.
Frankly I think it will boil down to whether chimps clade exclusively
with gorillas or with humans.  If chimps clade with humans (as most
might expect), it will consolidate support for that popular hypothesis
even further.  However, if chimps clade exclusively with gorillas, then
we will still be faced with the problem of whether humans and orangutans
are a clade which is sister to gorillas and chimps, or if it is a
paraphyletic grouping sharing plesiomorphies which were subsequently
lost in a gorilla-chimp clade.      
      Until the first whole genome analysis of the great apes appears, I
see little point in debating the issue further.  The only way morphology
could trump molecular data in this case would be a really spectacular
fossil find of the right age in the right place.  Therefore I believe
that genomic analysis will first provide a credible solution, and that
fossils will then confirm it morphologically at a future time.      
           ----------Ken Kinman   
 





More information about the Taxacom mailing list