Population Structure of Porthetes hispidus (Coleoptera: Curculionidae), a Pollinator of the African Cycad Encephalartos friderici-guilielmi

Abstract

Abstract Porthetes hispidus (Roheman) (Coleoptera: Curculionidae: Amorphocerini) is thought to be the primary pollinator of and is completely host specific to Encephalartos firiderici-guilielmi Lehmann, which is considered threatened. It is distributed across the Eastern Cape of South Africa. Here, genetic diversity and structure of a cycad-associated weevil, P. hispidus, was investigated using the cytochrome oxidase I (COI) and elongation factor la genes (EF-1α). Samples were taken from nine populations on isolated colonies of the host plant from across its known range. Nucleotide and haplotype diversity were moderate to high. Little to no phylogeographic structure was found, and very low values of FST and high values of Nm (COI: FST = 0.0759, Nm = 3.04; EF-1α: FST = -0.0175, Nm = ∞) indicated high levels of gene flow despite current geographical disjunctions. These data suggest that isolated colonies of E.friderici-guilielmi maintain a viable population of pollinators. However, more rapidly evolving markers may reveal current genetic differentiation that did not exist in the past.