a Time-calibrated phylogenetic tree of families, with the number of species and sampling plots in parentheses (the three major taxa are represented in a single tree for representative purposes only). b, d, f Scatterplots representing how dissimilarities in community responses or organismal traits, quantified as effect sizes or raw differences on the y-axis, increase with evolutionary time, represented by patristic distances in million years (Ma) in the x-axis; each point represents a pairwise comparison between families. c, e, g The density plots below each scatterplot represent, for the same variables as scatterplots, the distribution of the likelihood ratio statistics δ for a two model comparison, a null model with random draws independent of the phylogeny (white noise WN model, lighter density distributions) and a Brownian motion BM model of evolution (darker density distributions). The dashed vertical line indicates the observed value of δ when the models are fit to our data set. A total of 1000 replicates were used for each distribution. Peak-α: elevation at which species richness peaks. Edf-α effective number of parameters of the smoothing function, Slopez elevational turnover, R2z magnitude of elevational turnover. Source data are provided as a Source Data file.