Fk. Barker et Sm. Lanyon, The impact of parsimony weighting schemes on inferred relationships among toucans and neotropical barbets (Aves : Piciformes), MOL PHYL EV, 15(2), 2000, pp. 215-234
The development of new schemes for weighting DNA sequence data for phylogen
etic analysis continues to outpace the development of consensus on the most
appropriate weights. The present study is an exploration of the similariti
es and differences between results from 22 character weighting schemes when
applied to a study of barbet and toucan (traditional avian families Capito
nidae and Ramphastidae) phylogenetic relationships, The dataset comprises c
ytochrome b sequences for representatives of all toucan and Neotropical bar
bet genera, as well as for several genera of Paleotropical barbets, The 22
weighting schemes produced conflicting patterns of relationship among taxa,
often with conflicting patterns each receiving strong bootstrap support. U
se of multiple weighting schemes helped to identify the source within the d
ataset (codon position, transitions, transversions) of the various putative
phylogenetic signals. Importantly, some phylogenetic hypotheses were consi
stently supported despite the wide range of weights employed, The use of ph
ylogenetic frameworks to summarize the results of these multiple analyses p
roved very informative. Relationships among barbets and toucans inferred fr
om these data support the paraphyly of the traditional Capitonidae, Additio
nally, these data support paraplnyly of Neotropical barbets, but rather tha
n indicating a relationship between Semnornis and toucans, as previously su
ggested by morphological data, most analyses indicate a basal position of S
emnornis within the Neotropical radiation. The cytochrome b data also allow
inference of relationships among toucans. Supported hypotheses include Ram
phastos as the sister to all other toucans, a close relationship of Baillon
ius and Pteroglossus with these two genera as the sister group to an (Andig
ena, Selenidera) clade, and the latter four genera as a sister group to Aul
acorhynchus. (C) 2000 Academic Press.