Taxonomic publications: past and future - Senckenberg Museum

Burckhardt & Mühlethaler (eds): 8 th GfBS Annual Conference Abstracts 24
New phylogenies and past classifications – should we compare the two?
T. Dikow
Recently, many phylogenies of a diverse array of taxa have been published that
are solely based on DNA-sequence data. Typically, these “new” phylogenies are
compared to previously established classifications that were not necessarily
derived from the rigorous methodologies of current phylogenetic systematics.
These comparisons often detail the support that the “new” phylogenies give to
established taxa without added insight into how such molecular studies can
improve our classifications. The validity of simple comparisons of long established
classifications and “new” molecular phylogenies will be discussed in light of three
evident theoretical problems: (1) Can we compare the two hypotheses if both are
not grounded in phylogenetic methodology? (2) Can molecular characters test
morphological ones? and (3) Can new phylogenies test monophyly of taxa in
previous classifications?
Using a recently published molecular phylogeny of robber flies (Insecta: Diptera:
Asilidae) as an example, it is shown that the common line of argumentation in
molecular publications is unsound for two main reasons. First, the sheer
comparison of molecular and morphological hypotheses does not entail a scientific
test because morphological features used as the basis for the previous
classifications are not incorporated into the molecular analysis and, therefore, the
morphological characters remain as yet-to-be-tested hypotheses of homology.
Second, earlier classifications may be based only on a few diagnostic features
without character assessment in the Hennigian sense, and accompanying
published diagrams of relationships therefore are not cladograms in a strict sense.
Interpretation of past classifications should go beyond a simple comparison by
understanding how previous classifications and diagrams of relationships were
obtained, and what information they hold that can be simultaneously tested with
molecular characters. Rather than simply discussing similarities and differences,
modern phylogenetic studies can improve past classifications by employing (1)
many character complexes (behavioural, molecular, morphological etc.); (2) broad
taxon sampling (ingroup and outgroup); and (3) combined, simultaneous
phylogenetic analysis of all character complexes. Modern taxonomic research
projects should translate the newly obtained information into phylogenetic
classifications entailing diagnoses and identification tools, which can then be used
by biologists of a variety of fields and bring light to their scientific questions. This is
the central role of taxonomy in the biological sciences and we are the ones who
can deliver this knowledge.
Org. Divers. Evol. 5, Electr. Suppl. 13 (2005)