Invading Africa: a novel transoceanic dispersal by a New World ant parasitoid. (15th June 2016) - Murray, Elizabeth A.
Abstract: Aim: An ant parasitoid wasp genus (Eucharitidae: Kapala ) common in the New World exhibits the intriguing pattern of having one species distributed widely across tropical Africa and Madagascar. The unusual distribution prompted an investigation of the age, origins and diversification of the Afrotropical Kapala species. We evaluate a previous hypothesis that the species was anthropogenically introduced. Location: Africa and Madagascar and the Neotropics. Methods: Numerous forms of evidence are incorporated to explain the origin of the Afrotropical species Kapala ivorensis, including phylogenetic relationships, molecular dating estimates, inter‐ and intraspecific genetic distances, morphology and geography. A phylogenetic analysis was performed using six gene regions (18S, 28S‐D2, 28S‐D3‐D5, ITS2, COI and COII), and network and haplotype analyses were executed with subsets of the data. Two mitochondrial gene fragments were used to calculate divergence times under a strict clock model. Additionally, we tested for a correlation between genetic distance and geographical distance in K. ivorensis populations. Results: Phylogenetic analysis supports one evolutionary origin of K. ivorensis from within a clade of New World relatives. Network and haplotype analyses of the species show no biogeographical structure, and additionally, there is no statistical phylogeographical signal. These results, in conjunction with the low amount of phenotypic intraspecific variation and the genetic distance to the nearest New World relative, provide sufficient evidence to maintain the Old World Kapala as one species. Estimated mitochondrial mutation rates suggest that this species is over 1 Myr old, thus predating any potential for recent human introduction. Main conclusions: Multiple analytical methods indicate the Afrotropical K. ivorensis is molecularly distinct from the Neotropical sister species and originated from a single pre‐human dispersal. This is the first dated example of an insect that has colonized Africa via trans‐Atlantic dispersal from South America.