BSC phenetic vs. genetic

B. J. Tindall bti at DSMZ.DE
Thu Nov 16 09:52:40 CST 2000

Frederick W. Schueler wrote:
"is to somehow test the hypothesis that the phenetic and
genetic patterns of similarity, dissimilarity, geography, etc., seen the
full range of organic taxa are or are not similar to those we see in
familiar sexual, non-colonial, motile-but-not-planktonic, short-lived,
Vertebrates and Insects."

I keep seeing the contrast phenetic - genetic, which even Harrison picked
up in the 1960's as being "not what was intended". One can use the contrast
phenotype - genotype or genetic - epigenetic, but a phenetic system can
include both phenotypic and genotypic data (see Cain & Harrison's
definition). The problem comes in an extreme situation where a phenetic
system uses only genetic data and, thus "phenetic" and "genetic" are one
and the same. Of course if one says "phenetic and genetic patterns of
similarity, dissimilarity", then it implies an overall "phenetic"
evaluation of phenotypic and genotypic data.

This brings me to the interesting point that one is often given the
impression that genotype and phenotype are giving us different information
about taxonomy and/or evolution (particularly in prokaryotes). The problem
lies rather in the reliability of a data set and what one is trying to
achieve. There are some very interesting correlations between the 16S rDNA
data in prokaryotes and certain aspects of the phenotype (which keeps
getting missed). In eukaryotes one finds the same correlation in morphology
(phenotype) and certain aspects of the molecular genetic data. Okay, so
biology is more complex than that, but the first insghts into total genome
sequences show that there is an awful lot we do not know, and that much of
this knowledge is to be gained at the phenotypic level (enzymes, structural
proteins etc.), not at the genetic level. Since enzymes and structural
proteins are coded for by genes, there is a link.
Brian Tindall
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