[Taxacom] Order Homoptera probably not paraphyletic after all

Doug Yanega dyanega at ucr.edu
Tue Feb 24 13:53:27 CST 2015


On 2/24/15 11:12 AM, Kenneth Kinman wrote:
> Dear All,                                 Many entomologists today regard Homoptera as paraphyletic, and therefore have dumped them in with the Heteroptera into an expanded Hemiptera sensu lato.  I never have liked this great expansion of Hemiptera to also include all the Homoptera, (and of course, it is not necessary if one considers paraphyletic taxa as natural and useful).                         In any case, a fairly recent paper (published a little over 2 years ago) was published in PLOS ONE which presents molecular evidence that Homoptera is probably holophyletic after all, and a sister group to Heteroptera.  They show that most trees actually show a holophyletic (strictly monophyletic) Homoptera, and that those few trees showing a paraphyletic Homoptera are skewed due to long branch attraction with outgroup taxa.
Very limited evidence, based on very limited taxon sampling. Notably, 
they lack data for membracids, cicadas, scale insects, enicocephalids, 
and coleorrhynchans (!), and many of the sampled taxa are not basal in 
their respective clades. Anyone who is familiar with molecular work 
knows how dramatically tree topology changes with more exhaustive taxon 
sampling, especially when there are problems with long branches, which 
the authors point out as a problem here. The easiest way to make long 
branches go away is to include more taxa. It's not so much about the 
number of genes, really, but filling in the taxonomic gaps well (though 
it does require that the genes evolve at a rate appropriate for the 
level of analysis - ordinal-level questions require slower-evolving 
genes). I'm waiting until I see a tree with at LEAST every hemipteran 
superfamily represented, if not every family.

Peace,

-- 
Doug Yanega      Dept. of Entomology       Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314     skype: dyanega
phone: (951) 827-4315 (disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82




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