Indiscriminate data aggregation in ecological meta-analysis underestimates impacts of invasive species

Abstract

Exotic species are a growing ecological threat, although their factual ecological effects are currently debated. Our global meta-analysis recently reported that marine exotic species have an overall significant, but modest, effect on native communities. Thomsen2 argues that the data in this meta-analysis were aggregated in a manner that might underestimate the ecological impacts of marine exoticspecies. Here we discuss the data aggregation methodologies proposed by Thomsen and evaluate, when possible, whether the findings meet the expectations.