%0 Journal Article %T Genetic variation in the invasive avian parasite, Philornis downsi (Diptera, Muscidae) on the Gal¨¢pagos archipelago %A Rachael Y Dudaniec %A Michael G Gardner %A Steve Donnellan %A Sonia Kleindorfer %J BMC Ecology %D 2008 %I BioMed Central %R 10.1186/1472-6785-8-13 %X Both the mitochondrial and microsatellite data were consistent with there being a single species across islands. We found low genetic differentiation between islands and strong evidence for inter-island gene flow, or shared recent ancestry among individuals. Landscape genetic analysis identified two genetic clusters: one encompassing Santa Cruz and Isabela, and one on Floreana Island. There was no evidence of genetic differentiation between habitats and molecular variance was mainly attributable to within individuals. The combined P. downsi population was found to have undergone a population bottleneck.Philornis downsi populations have high connectivity within and between islands, with low levels of genetic differentiation between Floreana and the other two islands examined. The genetic bottleneck found across islands suggests there was a small founding population or few introduction events of P. downsi. The high dispersal capacity and wide habitat use of P. downsi highlights the significant threat that this parasite poses to the Gal¨¢pagos avifauna. Our findings are relevant for assessing the viability of methods to control P. downsi on Gal¨¢pagos, such as the sterile insect technique.Biological invasions threaten biodiversity and ecosystem function, with pronounced negative effects on islands in particular [1-3]. Genetic studies of invasive species can identify the adaptive potential of invaders to deal with new environmental conditions [4] or help to predict evolutionary responses to management practices (e.g. pesticides, biological control agents) [5]. Population bottlenecks affect many invasive species because they frequently experience founding effects that reduce genetic variability, but paradoxically, invasive species still manage to successfully establish and adapt to new environments [6]. However, the effects of bottlenecks may be countered by the occurrence of multiple introductions, high reproductive rates, and subsequent migration between locally bottlene %U http://www.biomedcentral.com/1472-6785/8/13