Non-Native Plants Alter Bird-Plant Frugivory Network Structure in a Human-Modified Tropical Landscape

Area of Science:

• Ecology
• Conservation Biology
• Island Biogeography

Background:

• Frugivory interactions are vital plant-animal mutualisms for seed dispersal and ecosystem resilience.
• Introduction of non-native plants by humans significantly alters these natural interaction networks.
• The impact of non-native plants on frugivory network structure and stability is poorly understood.

Purpose of the Study:

• To investigate how non-native plants influence the structure and robustness of frugivory networks in a human-modified tropical landscape.
• To quantify the contribution of non-native plants to the diets of frugivorous birds.
• To assess the consequences of non-native plant integration for network stability and secondary extinctions.

Main Methods:

• Utilized DNA metabarcoding on fecal samples from 21 frugivorous bird species in Gamboa, Panama.
• Identified consumed plant species and quantified the proportion of non-native plants in avian diets.
• Performed extinction simulations to evaluate network robustness under different scenarios.

Main Results:

• Non-native plants significantly altered network structure, decreasing nestedness while increasing connectance and modularity.
• Despite comprising 28% of plant species, non-natives disproportionately caused secondary bird extinctions.
• Certain non-native species acted as key connectors, linking network modules but showing lower persistence during bird removals.

Conclusions:

• Non-native plants reshape frugivory networks, posing a dual threat by increasing connectivity and undermining stability.
• Highly connected non-native species may facilitate invasions and compromise ecosystem integrity.
• Management strategies should focus on monitoring and controlling impactful non-native plants in human-modified ecosystems.