While ecological dissimilarity plays a critical role in biological invasions, it remains unclear whether ecological differences between alien species and co-occurring species in their native range persist after introduction.

Leveraging the unidirectional introduction of plant species native to the Mediterranean into California, we conducted a cross-continental study to examine whether Mediterranean-origin species are phylogenetically and functionally distinct from co-occurring species in their native range, and whether these differences are maintained relative to California native species after introduction.

Mediterranean-origin species introduced to California were phylogenetically and functionally distant from co-occurring native species in both native and introduced ranges. They also exhibited distinct patterns of trait coordination between stress tolerance-related traits (e.g., leaf dry matter content) and resource acquisition-related traits (e.g., leaf nitrogen concentration and specific root length), and a more acquisitive strategy across ranges.

Synthesis. These findings suggest that ecological dissimilarity and persistent trait coordination of species in their home range may contribute to their establishment after introduction, highlighting the value of native-range trait information for understanding invasion functional strategies in novel environments.