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).