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.