Phylogenetic Generalized Least Squares
Samples analyzed by sample type and each alpha diversity measurement
(observed, Shannon, and Simpson) from all samples from the same species
were averaged together to get a single set of measurements per host
species. In the full dataset, the non-phylogenetically controlled
regression found a single test to be marginally significant (cloaca,
Simpson, p =0.048); all other tests had p >0.05
(Table 1, Supplemental Fig. S2). Using PGLS on the full dataset, all
three alpha diversity metrics for the blood microbiota were
significantly associated with bird mass (p <0.001); all
other comparisons were not significant (p >0.17).
When looking at the Passeriformes-only dataset, the non-phylogenetically
controlled regression found a single test to be marginally significant
(cloaca, Shannon, p =0.022); all other tests hadp >0.05 (Table 1, Supplemental Fig. S3). Using PGLS
on the Passeriformes-only dataset, all three alpha diversity metrics for
the cloacal microbiota were significantly associated with bird mass
(p <0.05). Two of the gizzard microbiota tests were also
significant (p <0.05) but we note that this dataset has
extremely low sample size (N=9 individuals from 8 species). All other
comparisons were not significant.