Quantitative cophylogenetic spatial framework
To obtain a deeper understanding of the coevolution of interacting clades, we asked whether speciation in one of the partners influenced morphology in the other. To this purpose, we estimated distance matrices based on morphological traits for both plant and lemur species. Next, we superimpose each matrix with the phylogenetic distances of the interacting partner (plants when morphology was from lemurs, and lemurs when morphology was from plants) using a procrustean approach (Blasco-Costa et al. 2021). Coordinates derived from principal component analyses (PCA) were used to compute morphological distances between species for lemurs and plants (Supplementary Material S7). For plants, we only had complete data for fruit and seed length and width, so we restricted the analyses to frugivory interactions, while for lemurs we had body mass, body length, and tail length for all the species. Congruence values were considered to be significant whenever it was smaller than 95% of the values obtained from 1000 randomizations of each interaction matrix. A significant congruence of plant phylogeny with lemur morphology would suggest that plant speciation determined lemur body size, while a significant congruence of lemur phylogeny with plant morphology would be more consistent with the view that lemur speciation determined fruit and seed sizes.