Welcome to the New Year and the start of a new campaign: Paraphyly Watch 2009
The aim is to document, as comprehensively as possible, all the misuses and abuses of paraphyly in the scientific and popular literature for 2009.
- By paraphyly we mean non-monophyletic groups or taxa (e.g., grades).
- By misuse, we mean accepting paraphyletic groups* as informative (e.g., using them in analysis).
- By abuse we mean treating paraphyly as being evolutionary or evidence for evolution (e.g., accepting non-monophyletic groups in taxonomy and evolutionary biology).
In December we will award the Pewter Leprechaun to the most outrageous misuse and/or abuse of Paraphyly for 2009.
To start off our watch we have picked up two exemplary cases of paraphyly misuse and abuse in last 2008 issue of Taxon 57(4) by R.K. Brummitt and R.A. Zander.
Brummitt's Evolution in taxonomic perspective consists of several abuses of paraphyly:
- "... emphasis has been increasingly placed on the need for a classification which recognises evolution" (Brummitt, 2008:1050).
- "To overcome these objections to cladistic taxonomy, its proponents argue that we are dealing only with present day taxa and must ignore ancestors because we do not have them and so cannot name them. So at the same time as they define paraphyly in terms of ancestry, they insist on ignoring ancestors (Brummitt, 2008:1050)."
Possibly Brummitt's most incredulous slogan is
- "One cannot avoid paraphyletic groups. Again, 'Evolution is paraphyly all the way'..."
Zander's Evolutionary inferences from non-monophyly on molecular trees starts off promisingly:
- "I here suggest that not only is paraphyly acceptable, but non-monophyly in general may be evolutionarily informative. Non-monophyly of taxa is satisfied by either a paraphyletic" (Zander, 2008:1182).
- "Two different species of the same non-monophyletic genus imply an ancestor with phenotype resolvable only at the genus level" (Zander, 2008:1182).
- "Classifications based on phylogeny should be changed to accommodate non-monophyly-based taxon trees" (Zander, 2008: 1183).
The blight of paraphyly abuse and misuse is one commonly associated with other mistakes such as confusing taxa as species:
- "The exemplars A1 and A2 are paraphyletic, and if A is a species, then the ancestor of A1, A2 and species B is species A" (Zander, 2008: 1184).
- "The cladistic movement of the late 20th century has now split into two. Some can see the impossibility of classification into ranked taxa without any being paraphyletic, and have moved on to the PhyloCode with all its practical disadvantages arising from the abandonment of ranks" (Brummitt, 2008:1050).
* Hennig (1966: 146) defines paraphyletic groups as " ... distinguished from the monophyletic ones essentially by the fact that they have no independent history and thus possess neither reality nor individuality".
Brummitt, R.K. (2008). Evolution in taxonomic perspective Taxon 57:1049–1050.
Hennig, W. 1966. Phylogenetic systematics. The University of Illinois Press, Urbana.
Zander, R.H. (2008). Evolutionary inferences from non-monophyly on molecular trees Taxon 57:1182-1188.