Talk:Brachycera

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[edit] Higher Diptera classification: a compromise

There are grave difficulties in trying to place the most recent phylogenetic classifications of Brachycera into the Wiki framework, as these classifications are non-Linnaean (they do not have named ranks or proper rank equivalency of sister taxa). The rank of Infraorder is where the problem is most directly noticeable: if, for example, Muscomorpha is defined (as in THE most recent trees) as the entire sister clade to the (Stratiomyomorpha + (Xylophagomorpha + Tabanomorpha)), then one is left attempting to come up with four interstitial "ranks" between the Infraorder and Superfamily levels - and something at this rank must then be declared sister to the superfamily Empidoidea. While this looks okay when drawn as a tree (like on the infamous Tree of Life page), it cannot be wedged into a normal hierarchy in Wikipedia (e.g., the two subgroups of "Eremoneura" - a rankless taxon - are the superfamily Empidoidea and the rankless taxon "Cyclorrhapha" - which is certainly NOT a superfamily).

The alternative is to recognize one paraphyletic Infraorder, the Asilomorpha, consisting of (Nemestrinoidea + (Asiloidea + Empidoidea)) - which is, in fact, a historically widely-used and stable taxon name - in which case the name Muscomorpha can replace "Cyclorrhapha" (since the "Orthorrhapha" is a name long-gone anyway) and the only interstitial ranks needed then are two which are already in widespread use: the Sections Aschiza and Schizophora, and the Subsections of the latter, the Acalyptratae and Calyptratae. It is admittedly a clumsy workaround, if the phylogenetic trees are accurate, but it has the distinct advantage of allowing the Linnaean Wiki hierarchy to remain intact, AND it makes use of names (and their constituent subgroups) in a manner that is consistent with their historical use and definitions, even if we now know that those uses are not entirely appropriate. Moreover, given the incredible rate at which new trees and classifications of Brachycera are appearing (I think there's been something like 5 different trees in the last three years), this portion of the hierarchy is going to be nearly impossible to maintain in an up-to-date manner. Ideally, it would be best to have a stable and widely-accepted classification, which is simply not available at the moment. Moreover, given that the systematists working on Diptera are almost all cladists, it is unlikely that the future classification of Diptera will ever again utilize the Linnaean hierarchy of ranks - they simply assign names to clades, and do not state whether name X is a superfamily, infraorder, suborder, division, etc. - it's simply a name with no rank.

The bottom line is that maintaining Wikipedia's pages for this and other similar groups is going to require adopting a compromise classification if it's going to function at all. Dyanega 16:33, 16 June 2006 (UTC)