Molecular taxonomy: on way out?

Les at Les at
Wed Jul 20 09:46:46 CDT 2005

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.

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

More information about the Taxacom mailing list