Model selection in statistical historical biogeography of Neotropical insects-The Exophthalmus genus complex (Curculionidae: Entiminae)

Abstract

Statistical historical biogeographic methods rely on models that represent various biogeographic processes. Until recently model selection in this domain was not widely used, and the impact of differential model selection on inferring biogeographic scenarios was not well understood. Focusing on Neotropical weevils in the Exophthalmus genus complex (EGC) (Insecta: Curculionidae: Entiminae), we compare three commonly used biogeographic models - DIVA (Dispersal-Vicariance Analysis), DEC (Dispersal-Extinction-Cladogenesis) and BayArea (Bayesian Analysis of Biogeography), and examine the impact of modeling founder-event jump dispersal on historical biogeographic reconstructions. We also investigate the biogeographic events that have shaped patterns of distribution, diversification, and endemism in this weevil lineage. We sample representatives of 65 species of the EGC and 26 outgroup terminals from the Neotropics, including Caribbean islands and the mainland. We reconstruct a molecular phylogeny based on six genes and apply molecular dating using a relaxed clock with three fossil calibration points. Historical biogeographic estimations and alternative biogeographic models are computed and compared with the R package BioGeoBEARS. Model selection strongly favors biogeographic models that include founder-event jump dispersal. Without modeling jump dispersal, estimations based on the three biogeographic models are dramatically different, especially for early-diverging nodes. When jump dispersal is included, the three biogeographic models perform similarly. Accordingly, we show that the Neotropical mainland was colonized by Caribbean species in the early Miocene, and that in situ diversification accounts for a majority (∼75%) of the biogeographic events in the EGC. Our study highlights the need to assess wide-ranging historical biogeographic processes - including founder-event jump dispersal - for best-fitting statistical Caribbean biogeographic reconstructions. Moreover, colonization of the Neotropical mainland from the Caribbean reinforces the notion that islands can be an important source of continental diversity.

Keywords: Caribbean biogeography; Dispersal; Molecular dating; Statistical biogeography; West Indies.