How to chop up a tree

Abstract

Over the past 50 years it has been pointed out with increasing frequency that our traditional Linnaean system of classification and nomenclature is incompatible with a phylogenetic system which recognises only monophyletic groups. Dividing up an evolutionary tree into mutually exclusive families, genera, and species which are all monophyletic is a logical impossibility. Darwin had emphasised that evolution is descent with modification. The rise of cladistic thinking in the last 40 years has promoted an obsession with monophyletic taxa, with classification based solely on descent at the expense of modification. Despite strong psychological pressures on a generation of biologists who have been brought up on the dogma of monophyly, the Hennigian view of classification is now increasingly seen as illogical and out-of-date. Some are therefore supporting the PhyloCode, which is based on a logical position but is impractical for general purpose classification and communication since it recognises no ranks and abandons binomials. Others still cling to the nonsensical concept of recognising families, genera, species, etc., and all being monophyletic. Linnaean classification is the optimal tool for cataloguing biodiversity and will inevitably be m aintained, but this requires recognition of paraphyletic taxa and some rethinking of the practice and purposes of biological classification. Those who want a classification to recognise only monophyletic taxa should adopt an appropriate nomenclatural system such as is offered by the PhyloCode. To do otherwise will tend to lead to bad taxonomy.

Anti-intellectualism in the DNA Barcoding Enterprise

“…The recent 'paraphyly debate' for example, centers itself around finding evolutionary models to justify paraphyletic taxa, namely ancestral groups (see BRUMMITT 2002, CAVALIER-SMITH 2010. The debate cannot be resolved because genealogical arguments are being used to justify what is essentially a problem of biological classification.…”

Stability or stasis in the names of organisms: the evolving codes of nomenclature

“…Anything likely to increase stability has immediate appeal, but closer examination of the PhyloCode shows that claims about increases in stability are not held up (Forey 2002), and wholesale adoption would immediately cause widespread name changes-a decrease in stability. It has been suggested that cladistic methodology necessitates naming using something like the PhyloCode (Brummit 2002; but also see Nelson et al 2003) whereas the traditional codes are only applicable to taxonomy done non-cladistically. This is a gross oversimplification of how science proceeds; there is widespread acceptance of the utility and desirability of naming monophyletic groups, but we still have far to go to really understand the shape of the tree of life.…”

Supplemental Material for 'The amphibian tree of life. (Bulletin of the AMNH ; no. 297)'

“…The ranked and rankless alternatives to expressing phylogenetic relationships in words theoretically are endless but most recently and most clearly discussed by Kluge (2005). To oversimplify his paper, currently competing systems for expressing phylogenetic relationships in words are (1) Linnaean system (Linnaeus, 1758); (2) We have taken a sixth approach, one that we think is based on common sense, especially with respect to how systematists use taxonomies and with respect to the state of the discussion, which is still very preliminary and reflecting a deep ambivalence on the part of taxonomists (for all sides of the controversy see : Wiley, 1981;de Queiroz, 1988;de Queiroz and Gauthier, 1994;Cantino et al, 1997;Cantino et al, 1999;Benton, 2000;Nixon and Carpenter, 2000;Withgott, 2000;Kress and DePriest, 2001;Niklas, 2001;Papavero et al, 2001;Pennisi, 2001;Brummitt, 2002;Carpenter, 2003;Keller et al, 2003;Kojima, 2003;Nixon et al, 2003;Schuh, 2003;Kluge, 2005;Pickett, 2005). What we do think is that the conversation will continue for some time and that changes will take place, all discussed fully and not driven by the overheated sloganeering that, unfortunately, characterizes so much of the rhetoric at this time-on all sides-inasmuch as this is a political, not a scientific controversy (see Pickett, 2005, for discussion).…”