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phylogenetics



I have been listening with much interest to discussions on this server for
several weeks, and now only find some time to put in my two cents' worth.
Get out your salt shakers.

I am a molecular geneticist at The Ohio State University, probably better
known as the 7-0 Buckeyes with 3 Heisman candidates.  I work in the
Laboratory of Evolutionary Genetics and sequence dinosaur DNA, specifically
clock genes like the 18S ribosomal RNA gene.  What I want to make clear is
that morphological characteristics of any organism, (phenotype), represent
only 1 to 2% of the TOTAL genome. Morphological characteristics taken from
the fossil record cannot address the species issue adequately.  Skeletal
remains tell virtually nothing about physiology, which, by the way, includes
mating and fertile or sterile offspring.  Morphological characteristics can
be misleading, easpecially in the case of parallel evolution and
convergence, which are more common than one might imagine. Genetype changes,
as a rule, faster than phenotype, thus adding more confusion to the issue.
True species identification cannot be based on morphology alone, nor can
morphology predict common ancestral states in a phylogenetic analysis.
Genetic sequences can do this, and as technology progresses, like it is in
our lab, the burden will largely be on the morphologists to reconcile their
data with the genetic data. Just a friendly piece of advice to those who are
interested in pursuing the field of paleontology.... take a few genetics
courses!

-Chip Pretzman