A trait-based approach to assess niche overlap and functional distinctiveness between non-indigenous and native species

Our understanding of the community assembly processes acting on
non-indigenous species (NIS), as well as the relationship with native
species is limited, especially in marine ecosystems. To overcome this
knowledge gap we here develop a trait-based approach based on the
functional distinctiveness metric to assess niche overlap between NIS and
native species, using high-resolution data on benthic invertebrate
communities in the Baltic Sea. Our results show that NIS retain a certain
degree of similarity with native species, but display one or a few
singular unique traits (e.g., bioturbation ability). Furthermore, we
demonstrate that community assembly processes, including both
environmental filtering and limiting similarity affect NIS establishment,
but that their effects may be highly context dependent, as illustrated by
pronounced spatial patterns in distinctiveness. Finally, our trait-based
approach provides a generic framework applicable to other areas and
organisms, to better understand and address biological
invasions.