Phylogenetic signal and potential for invasiveness
We hypothesized that the evolutionary stability of insect traits relevant to invasion risk can be used to characterize this risk and the confidence in assigning potential invasiveness. Different longhorned beetle species have biological trait combinations (diet breadth, host tree condition and adult feeding) that predispose them to different degrees of potential invasiveness if introduced outside their native range. Relevant biological information is often not available for newly introduced species; however, the approach described in the present study could rapidly allow risk to be assigned to such discoveries. To test this approach, we used a molecular phylogeny for 56 species of Cerambycidae from five subfamilies to measure phylogenetic signal associated with invasive traits. The biological traits were used to cluster species into seven hypothesized risk groups. Mapping these risk designations back onto the phylogeny allowed us to examine the risk within clades at different taxonomic levels and the stability of the risk designation. We used additional species known to be non-native invasive problems to test our framework. Our method would have correctly predicted the risk of Anoplophora glabripennis (Motschulsky) but not Callidiellum rufipenne (Motschulsky). There was significant phylogenetic signal in both the biological traits and the risk category membership. Our approach can be modified for other groups of concern.