Climate change reshapes the eco-evolutionary dynamics of a Neotropical seed dispersal system

Aim: Global changes will redistribute biodiversity, reshaping ecological
interactions and ecosystem processes. The distribution decoupling of
plants and their mutualistic seed dispersers, for instance, may have
overlooked eco-evolutionary effects. How animal-dispersed plants will
respond to changes in the distribution of their seed dispersers is,
however, an open question. Here, we forecast the consequences of climate
change and frugivory interactions for the spatial distribution and seed
size evolution of a Neotropical palm. Location: Atlantic forests of South
America Time period: Present day, end of 21st Century Major taxa studied:
Thirty-two species of frugivorous birds, and a palm (Euterpe
edulis).  Methods: Future patterns of animal-plant co-occurrence
were derived from ecological niche models, climate forecasts, projections
of future forest loss, and seed dispersal simulations. We further explored
the evolutionary effect of the spatial reorganization of interactions by
modelling palm seed sizes as function of changes in the distribution of
frugivore traits. Results: Our models indicate that future climate change
and deforestation may reduce the palm’s suitable distribution by 20-50%.
However, our simulations suggest that 66% of all remaining future suitable
distribution (76.200 km²) would still be inaccessible to the palm without
the active dispersal of seeds by frugivores. In addition, novel frugivore
communities are projected to have smaller body mass and gape size (-23%
and -10%, respectively), due to the loss of large frugivores, which may
translate into a 6–17% reduction of seed sizes across the palm’s remaining
distribution. Main conclusion: Our projections indicate that frugivore
seed dispersal may be critical to allow occupancy of future habitat by the
studied plant. However, loss of large frugivores may affect trait
selection regimes, creating hotspots of plant evolution towards smaller
seeds. We argue that such complex dynamics from species-specific responses
to global change may drive the distribution and evolution of several
interacting partners worldwide.