Non-native species drive biotic homogenization, but it depends on the realm, beta diversity facet and study design: A meta-analytic systematic review

While reducing the species richness of invaded communities is a well-known
consequence of biological invasions, non-native species can also reduce
variability between communities over time (i.e., beta diversity) in a
process known as biotic homogenization. Although biotic homogenization due
to non-native species is a common topic of theoretical reviews, we believe
no global meta-analysis on the effect of non-native species on beta
diversity has been carried out yet. Here, we systematically show that
non-native species drive biotic homogenization, but it depends on the
realm, beta diversity facet and study design. Biotic homogenization was
more intense in marine and freshwater ecosystems than in terrestrial
ecosystems. We also found that non-native species reduced both taxonomic
and phylogenetic beta diversity, but not the functional beta diversity.
Finally, we observed more intense effects using “before vs. after
invasion” followed by “uninvaded vs. invaded sites” while the effect size
of studies using “communities associated with native vs. non-native
species” did not differ from zero. Our findings highlight that non-native
species contribute to biotic homogenization as a prevalent pattern in
communities worldwide, and that biodiversity conservation strategies
should go beyond investigating the reduction in the number of species by
also taking into account beta diversity in its multiple facets.