When genetic markers contradict historical hypotheses: an unexpected Cypriot origin for the invasive seed chalcid Megastigmus schimitscheki.
Data and results presented in the present paper come from the original article: Auger-Rozenberg M.-A., Boivin T., Magnoux E., Courtin C., Roques A., Kerdelhué C., 2012. Inferences on population history of a seed chalcid wasp: invasion success despite a severe founder effect from an unexpected source population. Molecular Ecology, 21 (24), 6086-6103. Most invasive species established in Europe originate from either Asia or North America, but little is currently known about the potential of the Anatolian Peninsula (Asia Minor) and/or the Near East to constitute invasion sources. Mediterranean forests are generally fragile ecosystems that can be threatened by invasive organisms coming from different regions of the Mediterranean Basin, but for which historical data are difficult to gather and the phylogeographic patterns are still poorly understood for most terrestrial organisms. In this study, we characterized the genetic structure of Megastigmus schimitscheki, an invasive seed-feeding insect species originating from the Near East, and elucidated its invasion route in South-eastern France in the mid 1990's. Historical data suggested that the invasive populations originated from Turkey. To disentangle the evolutionary history of this introduction, we gathered samples from the main native regions (Taurus Mountains in Turkey, Lebanon and Cyprus) and from the invaded range, that we genotyped using five microsatellite markers and for which we sequenced the mitochondrial Cytochrome Oxidase I gene. We proposed a detailed phylogeographic pattern for the Near East populations, and we unambiguously showed that the French invasive populations originated from Cyprus, thereby contradicting the historical data. Interestingly, we could show that the introduced populations were founded from an extremely restricted number of individuals.