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.