The story so far...
- On the planet Zog, the Mayrian Monks enforce rigid elections that decide the fate of the foundations of science. One day new heretical “discoveries” of what are called ‘natural groups’ questions the validity of Reptiles - rulers of the land. The heretics have called them a group of ‘unrelated animals’ - nothing more than systematic bastards! The Mayr-Monks are never wrong and, science never gets in their way. A snap election is called, the ballot counted and science-democracy enforced. The vote was unanimous: 130 in favour - zero against. “Good to see science done” says one Monk to another. That night they all sleep peacefully with a clear conscious, awaiting morning when their sun will rotate around their flat earth once again.
Let’s kick off with Podani’s arguement, namely:
- “... that there are four major aspects of taxonomic systems in which achievements of evolutionary biology are not recognized fully and properly, if evolution is considered at all” (Podani, 2009: 1049).
- “If we use a synchronous classification for extant organisms, we are concerned with the result of evolution, history is only relevant as long as common ancestry is to be detected, and an inclusive hierarchy is suitable to summarize diversity of life” (Podani, 2009: 1050).
- “On the other hand, a diachronous classification cannot be Linnaean for two reasons: (1) units of classification and the groups change in time and, more importantly, (2) wide gaps necessary for separating supraspecific taxa are evolutionary absurdities in the spatio-temporal continuum of populations” (Podani, 2009: 1050).
- “The only tool for representing the diachronous pattern of life adequately is the Darwinian phylogenetic tree, showing ancestor–descendant relationships between extinct and extant populations” (Podani, 2009: 1050-1051; original emphasis).
- “I suggest restricting the original definition of monophyly to phylogenetic trees, so that it is a diachronous phenomenon and can only be examined in a diachronous classification. For cladograms, I introduced the new term monoclady: a group is monocladistic if it includes all terminals of a given clade. This condition has to do with extant taxa and is particularly meaningful for a synchronous classification” (Podani, 2009: 1051; original emphasis).
- “Reptiles are most certainly para- phyletic because extinct ones include the ancestors of birds and mammals as well. Extant reptiles are paracladistic, since crocodiles are sister to birds rather than to other reptiles” (Podani, 2009: 1051).
- “If a collection of organisms is found to be monocladistic (in a molecular study, for example), then the taxon which includes this group in a diachronous classification is not necessarily monophyletic. Paraclady means that the group cannot be embedded into a monophyletic taxon, and it is therefore indication of paraphyly or even polyphyly in the corresponding diachronous classification. A Linnaean taxon, which is preferably synchronous as the above logic dictates, can only be monocladistic, paracladistic or polycladistic and the monophyly/paraphyly problem vanishes. Paraphyly, as understood earlier, may often be reflection of the disagreement of a diachronous classification with a synchronous analysis. Therefore, the central tenet of contemporary taxonomy is perhaps not about paraphyly and monophyly, but around the contrast between synchronous and diachronous classifications” (Podani, 2009: 1052).
Here is how it works. First debunk monophyly as irrelevant to classification by assigning them as problems found in phylogenetic trees. Since phylogenetic trees are diachronous and diachronous classifications “cannot be Linnaean” and, are therefore invalid. Clever. Now he introduces a new term monoclady and monocladistic, which means, “If a collection of organisms is found to be monocladistic (in a molecular study, for example), then the taxon which includes this group in a diachronous classification is not necessarily monophyletic” (Podani, 2009: 1052). There we have it. Monocladistic groups can be paraphyletic seen from a phylogenetic perspective. Get it?
Let’s put it another way. Take an existing term like monophyly and replace it with a similar term like monoclady (“includes all terminals of a given clade”), which of course does not change its overall meaning. Now dismiss monophyly as irrelevant to classification, but relevant to 19th century Haeckelian phylogenetics, hence radically changing not only its meaning but also its usage. Here comes the best bit - do the same to paraphyly. Replace its overall meaning with another term, like paraclady, and then dismiss paraphyly as irrelevant to classification. No problems here (as it is not relevant to classification). The coupe de grace is defining some forms of monoclady (formerly monophyly) as paraphyly! Wow, the sheer audacity!
Yes folks, I think we have a clear forerunner in the 2009 Pewter Leprechaun for the misuse and abuse of paraphyly.
As you read, judges are conferring in what is to be some pretty stiff competition. The results for the Winner of the 2009 Pewter Leprechaun will be announced very soon. Stay tuned!
Ebach, M.C. & Williams, D.M. (2004). Classification. Taxon 53: 791–794.
Podani, J. (2009). Taxonomy versus evolution Taxon (58), 1049-1053.
Stuessy, T.F. & König, C. (2009). Classification should not be constrained solely by branching topology in a cladistic context Taxon, 58, 347-348.