Phylogenetic mixed models for molt and dichromatism extents
We built phylogenetic mixed models to predict the presence and extent of
prealternate molt and seasonal dichromatism to understand the relative
influences of life history and environmental variables on these traits.
To build mixed models of exogenous correlates of molt extents, we first
conducted pairwise phylogenetic generalized least squares analysis over
extents of molt, dichromatism, and exogenous correlates (extended data
table 1) using the package caper (Orme et al. 2013) in R. We examined
pairwise PGLS results for strength and significance of interactions and
used these interactions to build sets of mixed models to test for the
effects of exogenous drivers on extents of molts and dichromatism by
examining pairwise interaction between molts, dichromatism, and
ecological data, as well as covariation between life history and
ecological correlates. We evaluated these mixed models using caper,
MuMIn (Barton 2016) and Nlme (Pinheiro et al. 2016) in
R, and organized the models using information theory by ranking models
by their AICc score (Table 1).