Figure 1 – Contribution of each lemur genus to the overall
cophylogenetic signal in (A) frugivory, (B) folivory, (C) florivory, and
(D) granivory, measured as Procrustean residuals. Colors highlight
differences among (1) feeding guilds and (2) activity pattern.
Silhouettes were built by the authors. Procrustean residuals measure the
variation in the topological fit that is not explained by the
cophylogenetic structure of the interaction matrix. Interactions with
small values contribute the most to CS, whereas those deviating more
from the shared phylogenetic history contribute the less to CS.
To more accurately demonstrate coevolution, we also need evidence that
phylogenetic distances and the dissimilarity between species in sets of
interacting partners co-vary for both plants and lemurs (PSI). Contrary
to our expectation of the existence of phylogenetic signal in species
interactions for both plants and lemurs, we found that cophylogenetic
patterns observed for frugivory, florivory and granivory emerged from
similar lemurs (in terms of the between-species dissimilarities in sets
of interacting partners) interacting with phylogenetic-related plants,
with no reciprocal trend (i. e. plant diversification was unaffected by
lemurs). In the case of folivory, however, phylogenetic congruence was
associated with significant phylogenetic signals for both plants and
lemurs. Nectarivores were the only group that did not show any evidence
of PSI for either plants or lemurs (Table 2).
Although the observed cophylogenetic patterns for frugivory do not
appear to reflect strong coevolution, we further investigated this
possibility by taking advantage of the existence of functionally
relevant morphological traits for both plants and lemurs. We found that,
in addition to the congruence between plant and lemur phylogenies
(significant CS), there was also congruence between lemur phylogeny and
plant morphology, and between plant phylogeny and lemur morphology
(Table 2). This result suggests that, to some extent, plant speciation
shaped lemur morphology (notably body size), at the same time that lemur
speciation somehow affected diaspore morphology (fruit and/or seed
sizes).
Table 2 – Cophylogenetic signal (CS) and Phylogenetic signal
in the interactions (PSI) between plants and lemurs