Impacts of Species Introductions on the Trait Diversity of Interacting Avian Frugivores and Fleshy‐Fruited Plants Depend on Native Trait Diversity

Abstract

ABSTRACT Aim The introduction of non‐native species to native ecological communities by humans is a major driver of global biodiversity change. Studying how species introductions influence interacting species is essential to understanding possible functional consequences of global change because biotic interactions are ecologically crucial. We explore how species introductions affect the diversity of functional traits within and between assemblages of interacting fleshy‐fruited plants and frugivorous birds. Location Multiple locations globally. Time Period Plant‐frugivore networks sampled between 1961 and 2018. Major Taxa Studied Fleshy‐fruited plants and avian frugivores. Methods For 25 frugivorous bird and 63 fleshy‐fruited plant assemblages, to which non‐native species were introduced, we assess differences in trait diversity and mean trait values and compare beta trait diversity with and without introduced species. We further test which factors explain differences in trait diversity with and without introduced species. To this end, we compile species' morphological traits that influence interactions between fleshy‐fruited plants and frugivorous birds and related ecosystem functions. Results Introduced species increased bird and plant trait diversity in assemblages with low native trait diversity but decreased it in assemblages with high native trait diversity. In bird assemblages, species introductions shifted mean values towards larger birds with wider bills and more pointed wings. In plant assemblages, mean trait values showed more variable changes. Comparisons between assemblages revealed that introduced species reduced the beta trait diversity of both frugivorous birds and fleshy‐fruited plants, suggesting biotic homogenisation in terms of their functional traits. Main Conclusion Changes in trait diversity within and between assemblages underscore that species introductions can have functional consequences for biotic interactions and related ecosystem functions, potentially influencing the functional availability of suitable interaction partners and the provisioning of seed dispersal. Continuing efforts to collect and publish data on species' functional traits will advance global change ecology.

The authors' abstract, as published at the source. Global Ecology and Biogeography, 2026 · DOI ↗