Molecular Systematics, Species Concepts, and Myrmecophytism in Cecropia (Cecropieae: Urticaceae): Insights from Restriction-Site Associated DNA

Cecropia is a group of fast-growing pioneer trees that are important in forest regeneration and a common ant-plant mutualism in the Neotropics. To investigate the evolution of mutualism between Cecropia and associated ants, a phylogenetic framework is necessary. Cecropia species are difficult to distinguish morphologically and conventional genetic markers are insufficiently variable to resolve the phylogenetic relationships among species. Our study aimed to compare the phylogenetic utility of restriction site associated DNA (RAD) sequencing to prior work based on commonly sequenced gene regions. RAD sequence data resolved and supported species-level relationships better than previous studies. We identified a deeply divergent non-myrmecophytic Glade including C. sciadophylla and African Musanga. Results from geographically widespread and morphologically heterogenous C. obtusifolia and C. angustifoha suggest that current synonymy has lumped phylogenetically divergent lineages. Reconstruction of ant associations on the highly supported Cecropia phylogeny inferred equal probability of the ancestor of Cecropia being myrmecophytic or not. More intensive genetic study is needed to refine species concepts in Cecropia.