phylogenetic relationships and classification of didelphid marsupials ...

66 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 322
Fig. 26. Scatterplot of percent GC content among didelphid sequences at first and second codon
positions versus percent GC content at third codon positions for the five genes included in this study.
didelphid terminal taxa. 21 To simplify comparisons
of support values among the many
(.1000) ingroup nodes recovered by these
analyses, we restrict our attention to bootstrap
frequencies (from MP and ML analyses)
and Bayesian posterior probabilities, both of
which have respectable statistical pedigrees
(Felsenstein, 1985; Efron et al., 1996; Huelsenbeck
et al., 2002) despite their imperfect
21 Marsupial interordinal relationships and relationships
among congeneric didelphid species will be treated in
subsequent reports.
relationship to type I error rates (Erixon et al.,
2003; Alfaro and Holder, 2006).
Analyses of Nonmolecular Data
Despite the large amount of missing data
from Chacodelphys (table 2), including this
taxon in a parsimony analysis of our
nonmolecular (morphological + karyotypic)
characters resulted in fewer equally parsimonious
trees (with a correspondingly betterresolved
strict consensus) than we obtained
from a parsimony analysis with Chacodelphys
excluded (table 12). Among other notewor-