Functional similarity shapes global patterns of fish naturalization and invasion richness.

Functional similarity between native and exotic fish species predicts invasion success and richness, with high similarity linked to greater success especially at high latitudes.

• Why it matters: Understanding why some exotic species establish and why some communities host more invasions is crucial for managing freshwater biodiversity threats caused by biological invasions.
• What they did: Analyzing data from 1,691 fish communities worldwide, researchers used trait-based methods to examine the relationship between functional similarity, climate, and invasion patterns across latitudes.
• The result: High functional similarity correlates with increased invasion success and richness, especially in stressful, high-latitude environments, highlighting the roles of ecological filtering and human impacts.