Revisiting competitive outcomes through a trait lens: a global meta-analysis across species provenance.

Biological invasions change the landscape of competition within communities and can have major consequences for biodiversity by driving competitive exclusion. However, the effects of competition on trait distributions are less understood, especially in how it depends on the native or nonnative provenance of the species involved. Here, we synthesize global data across plants and animals to investigate how competition alters trait distributions within species. We find that competition consistently reduces trait means and increases trait variation, following a directional-disruptive pattern. These effects depend on species provenance. Native competitors have limited influence on trait distributions within nonnatives, while nonnatives exert stronger impacts on natives. Morphological and life-history traits are especially responsive, whereas chemical and physiological traits show weak overall effects. However, nonnatives disproportionately affect the distribution of chemical and physiological traits. Intraspecific competition exerts a greater influence on trait distribution than interspecific competition, particularly in nonnatives. We discuss how these patterns align with key hypotheses on the evolution and ecology of species invasions. Our work provides insight into how competition shapes trait distributions and provides a trait-based null model for future tests of species interactions in the Anthropocene.