title: Globally distributed Xyleborus species reveal recurrent intercontinental dispersal in a landscape of ancient worldwide distributions.
abstract: BACKGROUND
  Invasive species can have devastating effects on native ecosystems and therefore impose a significant threat to human welfare. The introduction rate of invasive species has accelerated dramatically in recent times due to human activity (anthropogenic effects), with a steadily growing pool of widespread tramp species. We present an in-depth analysis of four pantropical species of Xyleborus ambrosia beetles (Xyleborus volvulus, Xyleborus perforans, Xyleborus ferrugineus, and Xyleborus affinis) with similar ecology (fungus cultivation in dead wood), reproductive biology (permanent inbreeding) and genetic system (haplodiploidy). The unique combination of reproductive traits and broad host plant usage pre-adapts these beetles for colonizing of new areas.
  
  
  RESULTS
  We found that all four species were broadly distributed long before human-assisted dispersal became common, and that the impact of anthropogenic effects varied among the species. For X. volvulus, X. perforans, and X. affinis there was evidence of ancient establishment in numerous regions, but also of abundant recent introductions into previously colonized areas. For X. ferrugineus, we found clear biogeographical structuring of old clades, but little evidence for recent successful introductions.
  
  
  CONCLUSIONS
  Our results indicate that current human-aided transoceanic dispersal has strongly affected the genetic makeup of three of the species in this study. However, current biogeographical patterns of all four species are equally, if not more strongly, influenced by ancient establishment on different continents.
authors.affiliation: Natural History Collections, University Museum of Bergen, University of Bergen, P.O. box 7800, 5020, Bergen, Norway. Jostein.Gohli@gmail.com.
authors.forename: Jostein
authors.initials: J
authors.lastname: Gohli
authors.affiliation: Department of Biology, University of Bergen, P.O. box 7800, 5020, Bergen, Norway.
authors.forename: Tina
authors.initials: T
authors.lastname: Selvarajah
authors.affiliation: Department of Biology, University of Bergen, P.O. box 7800, 5020, Bergen, Norway.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Kirkendall
authors.affiliation: Natural History Collections, University Museum of Bergen, University of Bergen, P.O. box 7800, 5020, Bergen, Norway.
authors.forename: Bjarte H
authors.initials: BH
authors.lastname: Jordal
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001517:Coleoptera / Q000145:classification / Q000502:physiology*; D017753:Ecosystem; D005260:Female; D014644:Genetic Variation; D058865:Introduced Species; D058974:Phylogeography; D048889:Weevils