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Contributed Talk

Session: : Invasion 2

COS 176-2 - Functional traits—not nativeness—shape the effects of megafauna on plants

Wednesday, August 9, 2023
10:15 AM – 10:30 AM PDT
Location: D137
Abstract: Mammalian herbivores (megafauna) have experienced dramatic extinctions and declines since prehistory. More recently, humans have inadvertently introduced numerous megafauna species, partially counteracting these declines numerically and restoring lost functional diversity. However, introduced megafauna—like other introduced species—are thought to have fundamentally distinct effects relative to native species because they lack long-term species- or population-specific coevolutionary history with native communities. If this is the case, then we should be able to empirically identify if a species is introduced or native by their ecological effects. Using a meta-analysis of 3,560 plant diversity and abundance responses from 208 studies, we found that megafauna effects were not shaped by nativeness, ‘invasiveness’, ‘feralness’, coevolutionary history, or functional and phylogenetic novelty. Introduced megafauna also did not facilitate introduced plants more than native megafauna. These results were consistent regardless of the landform’s evolutionary exposure to megafauna. Instead, we found that functional traits—particularly dietary selectivity and body mass—shaped megafauna impacts, with larger-bodied and generalist feeders promoting plant diversity. Our work suggests that trait-based ecology provides better insight into ecosystem functioning than concepts of nativeness.