Molecular taxonomy: on way out?

B.J.Tindall bti at DSMZ.DE
Wed Jul 20 06:05:47 CDT 2005

At 09:46 20.7.2005 +0800, Les Watson wrote:
>While it has been apparent for about forty years that comparative DNA
>studies would ultimately provide conclusive evidence for understanding
>phylogeny, classifications derived via DNA sequencing will not be definitive
>unless the taxonomic coverage is adequate, and the DNA sampled can be
>confidently assumed represent complete genomes. Many DNA-based
>classifications of plants have failed to meet even the first criterion, and
>few if any come near to satisfying the second; indeed, those derived
>entirely from chloroplast DNA do not directly represent nuclear genomes at
>all. Alternative methodologies for phylogenetically interpreting sequence
>comparisons will be easier to evaluate when the basic data are good enough.
...mmm, but chloroplasts are "degenerate" prokaryotes - might be
interesting to also check out recent information on obligate
symbiotic/parasitic prokyrotes which occur in eukaryotes - a VERY
interesting story. I would also suggest that you go back and carefully read
what Zuckerkandl and Pauling wrote when they introduced the concept of
"moleculaes as documents of evolutionary history" in 1965 - they advocated
the use of proteins and DNA, but they also raised interesting questions.


>Moreover, purported phylogenies are impossible to evaluate as such in the
>absence of adequate evidence from character correlations; and even if a
>classification truly reflects evolutionary relationships, it is useless if
>it does not bestow the ability to generalize about the contents of groups in
>terms of their structure, physiology, ecology, cytology, etc. For too long,
>people have been peddling revised classifications in the absence, fully
>operational, new or properly revised group descriptions. Editors of
>taxonomic journals should long ago have been automatically rejecting
>classificatory papers that fail to meet the obvious requirements of both
>good science and of practical applications of taxonomic systems, regardless
>of the kinds of data analyzed.
>Dr. Les Watson
>10, Maitland Avenue
>Little Grove, Albany,         Email: leswatson at
>WA 6330, Australia            Phone: +61 (8) 98 44 4398

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