Figure 2.

Phylogenetic Mantel correlogram showing significant phylogenetic signal across short phylogenetic distances. Solid and open symbols denote significant and nonsignificant correlations, respectively, relating between-OTU niche differences to between-OTU phylogenetic distances across a given phylogenetic distance. An optimal elevation and an optimal percent mud were estimated for each species; these values were taken to be estimates of OTU environmental niches across both abiotic axes. Significantly positive correlations indicate that ecological niche distance between OTUs increases with their phylogenetic distance, but only across the phylogenetic distance class being evaluated (that is, there is phylogenetic signal in OTU environmental niches).