On the origin of termite workers: weighing up the phylogenetic evidence.
Resolving the phylogenetic history of a 'true' worker caste in termites is essential to our understanding of termite eusocial evolution. Whether this caste is ancient and monophyletic or derived and polyphyletic will have a tremendous impact on our interpretation of termite eusocial history and remains an outstanding question in termite biology. Recent work has begun to re-examine this question in light of new phylogenetic information, but new questions have now arisen about how best to model character state changes in termite caste systems. In the present paper, we compare the models of Grandcolas and D'Haese [J. Evol. Biol. 15 (2002) 885] and Thompson et al. [J. Evol Biol. 13 (2000) 8691 and attempt to make explicit how these proposals differ with respect to the number of, and homology between, character states. We highlight the support each model has for the two principal, but competing, evolutionary hypotheses outlined above.
Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada. gjt@sfu.ca
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Thompson
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Kitade
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Crozier
D000818:Animals; D020049:Isoptera / Q000502:physiology*; D008954:Models, Biological; D010641:Phenotype; D010802:Phylogeny; D012930:Social Dominance