Fig. 4

Associations of microbiome structure with GI issues and hormone concentrations in African and Asian elephants. A African elephants with recent GI issues had lower bacterial ASV richness (LMM p = 0.042, N = no GI issue [n = 83]; Y = GI issues 6 weeks prior to fecal collection [n = 8]). B In Asian elephants, bacterial richness increased with yearly averages of total T3 (Wald X2 p = 0.0441). C The gut microbiome composition of African elephants was linked to changes in FGM concentration. Principal coordinate axis 1 from Unifrac distances plotted against FGM concentrations. D Thyroid hormones, total T3 and free T4, were significantly associated with gut microbiome composition of Asian elephants. Vectors on the MDS plot depict the correlation of total T3 and free T4 with the pattern in ordination space using Bray–Curtis distances. The length of the vector signifies the strength of the correlation (e.g. shorter arrows represent weaker correlations)