Previous studies have shown that the structure of mutualistic networks is influenced by factors like species abundance, phenological overlap, and trait matching. Phylogenetic effects where closely related species exhibit similar structural roles also play a part. However, systematic comparisons of these effects across different types of interactions (e.g., seed dispersal vs. pollination) and across trophic levels (e.g., birds vs. plants) within the same ecosystem have been limited.
In a study published in Journal of Animal Ecology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences revealed that evolutionary history has a stronger influence on birds than on plants, and on seed-dispersal networks compared to pollination networks.
The researchers conducted a comprehensive year-long field survey from May 2021 to April 2022 in a subtropical evergreen broadleaf forest in the Ailao Mountains of southwestern China. They constructed detailed mutualistic networks for both seed dispersal (involving birds consuming fruits and dispersing seeds) and pollination (involving birds feeding on nectar and transferring pollen).
By analyzing phylogenetic relationships among species and their ecological network roles, the researchers identified key factors affecting biodiversity and ecosystem stability.
They found that the number of interaction partners (species degree) exhibited weak phylogenetic signals in both birds and plants, indicating that closely related species do not necessarily interact with a similar number of other species.
In contrast, a stronger phylogenetic signal was observed in the composition of interaction partners. Closely related bird species—particularly frugivorous birds—interacted with taxonomically and phylogenetically similar partners. This trend was not observed in plants.
Moreover, in seed-dispersal networks, bird species that were evolutionarily specialized (phylogenetic specialists) also showed high specialization in their choice of interaction partners (interaction specialists). This correlation was not found for birds in pollination networks, nor for plants in either type of network.
“Our work is the first to directly compare phylogenetic effects in two distinct bird-plant mutualistic networks within the same ecosystem. It demonstrates that birds exhibit stronger phylogenetic effects than plants in shaping these networks, and these effects are more pronounced in seed-dispersal networks compared to pollination networks,” said HE Xuelian of XTBG.
A bird eating fruit. (Image by ZHU Ying)
First published: 13 October 2025
