Evolutionary cascades induced by large frugivores

Area of Science:

• Ecology
• Evolutionary Biology
• Botany

Background:

• Large frugivores are disappearing from global ecosystems, a process known as defaunation.
• The evolutionary impacts of frugivore loss on plant traits are poorly understood.
• Seed-dispersing vertebrates are crucial for plant reproduction and ecosystem health.

Purpose of the Study:

• To investigate the macroevolution of fruit traits in response to varying vertebrate diversity and size.
• To determine if frugivores exert significant selective pressure on fruit characteristics.
• To assess the impact of defaunation on plant morphology.

Main Methods:

• Phylogenetic analysis of over 400 plant species across 41 genera and five families in the Indo-Malay Archipelago.
• Comparison of fruit traits (size, color) in regions with differing vertebrate assemblages.
• Assessment of taxonomic and functional diversity of frugivorous birds and mammals.

Main Results:

• Average fruit size strongly correlated with the diversity and size of seed-dispersing vertebrates.
• Fruits were significantly smaller (40.2-46.5%) in regions with depauperate, small-bodied frugivore assemblages (Moluccas, Sulawesi) compared to diverse, large-bodied assemblages (Sunda Region).
• Fruit color showed no relationship with vertebrate diversity or the composition of frugivore guilds.

Conclusions:

• Vertebrate defaunation can drive significant evolutionary changes in plant fruit size.
• The decline of large frugivores due to overhunting imposes strong, specific selection pressures on plants.
• These findings underscore the critical role of large vertebrates in shaping plant evolution and maintaining ecosystem structure.