The role of phylogenetic relatedness on success of non‐native plants crossing the naturalization–invasion transition in North America

Abstract

Understanding the causes and consequences of biological invasions is a great challenge in ecology and conservation biology. The ability to predict which naturalized species are likely to become invasive would be a great step forward in managing and preventing invasions. The goal of this study is to test whether invasive species are a phylogenetically clustered subset of naturalized species at continental and regional scales, and to compare phylogenetic relatedness of invasive angiosperms with respect to species pools of non‐native naturalized angiosperms in North America. We divided North America into 65 state‐ or province‐level regions, and collated naturalized and invasive species lists of angiosperms for each region. Two phylogenetic metrics (net relatedness index (NRI) and nearest taxon index (NTI)), which represent different evolutionary depths, were used to quantify phylogenetic relatedness of naturalized and invasive angiosperms in North America, with respect to different species pools. We related phylogenetic relatedness of invasive angiosperms to climatic variables. We found that most invasive angiosperm assemblages are a phylogenetically clustered subset of their respective naturalized species pools, and the phylogenetic clustering of invasive species is greater in regions with lower temperature and precipitation. The pattern of phylogenetic clustering of invasive species likely reflects phylogenetic conservatism of traits associated with invasiveness. It may also reflect a tendency towards greater invasiveness for species with novel trait combinations compared to the non‐invasive naturalized species assemblages.