3.2 | Phylogeny-Independent β-Diversity
Euclidean distance, a phylogeny-independent β-diversity distance
measure, was significantly correlated with Julian date
(R2 = 0.02, p < 0.01),
longitude (R2 = 0.02, p <
0.01), distance from the population’s centre
(R2 = 0.02, p < 0.01), and
sandwort availability (R2 = 0.02, p< 0.01). The full PERMANOVA output is reported in Table S2 of
the Supporting information. Sandwort presence appeared to underlie the
primary ecological gradient in these communities based on PCA
visualization (Figure 4A). Furthermore, Euclidean distances were
correlated with the longitudinal distance separating horses
(rpearson = 0.37, p < 0.01;
Figure 4B). Additionally, in a univariate PERMANOVA, social band
membership was significantly correlated with Euclidean distances
(R2 = 0.66, p < 0.01).
Multi-model inference analysis of β-dispersion, a measure of β-diversity
between an individual horse’s microbiome and the horse population’s
theoretical average microbiome, indicated a negative correlation with
longitude (p = 0.01) and a positive correlation with distance
from the centre of the population (p = 0.03; Table S3, Supporting
information).