title: Transatlantic invasion routes and adaptive potential in North American populations of the invasive glossy buckthorn, Frangula alnus.
abstract: Many invasive species severely threaten native biodiversity and ecosystem functioning. One of the most prominent questions in invasion genetics is how invasive populations can overcome genetic founder effects to establish stable populations after colonization of new habitats. High native genetic diversity and multiple introductions are expected to increase genetic diversity and adaptive potential in the invasive range. Our aim was to identify the European source populations of Frangula alnus (glossy buckthorn), an ornamental and highly invasive woody species that was deliberately introduced into North America at the end of the 18th century. A second aim of this study was to assess the adaptive potential as an explanation for the invasion success of this species.
  
  
  
  Using a set of annotated single-nucleotide polymorphisms (SNPs) that were assigned a putative function based on sequence comparison with model species, a total of 38 native European and 21 invasive North American populations were subjected to distance-based structure and assignment analyses combined with population genomic tools. Genetic diversity at SNPs with ecologically relevant functions was considered as a proxy for adaptive potential.
  
  
  
  Patterns of invasion coincided with early modern transatlantic trading routes. Multiple introductions through transatlantic trade from a limited number of European port regions to American urban areas led to the establishment of bridgehead populations with high allelic richness and expected heterozygosity, allowing continuous secondary migration to natural areas.
  
  
  
  Targeted eradication of the urban populations, where the highest genetic diversity and adaptive potential were observed, offers a promising strategy to arrest further invasion of native American prairies and forests.
authors.affiliation: Plant Conservation and Population Biology, Biology Department, University of Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium Station d'Ecologie Théorique et Expérimentale du CNRS, Centre National de la Recherche Scientifique, 2 Route du CNRS, FR-09200 Moulis, France hanne.dekort@bio.kuleuven.be.
authors.forename: Hanne
authors.initials: H
authors.lastname: De Kort
authors.affiliation: Research Institute for Nature and Forest, Gaverstraat 4, B-9500 Geraardsbergen, Belgium.
authors.forename: Joachim
authors.initials: J
authors.lastname: Mergeay
authors.affiliation: Plant Conservation and Population Biology, Biology Department, University of Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Jacquemyn
authors.affiliation: Plant Conservation and Population Biology, Biology Department, University of Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Honnay
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D004463:Ecology; D014644:Genetic Variation; D058865:Introduced Species / Q000706:statistics & numerical data; D009656:North America; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D031955:Rhamnus / Q000235:genetics
keywords: Adaptive potential; Frangula alnus Mill.; conservation; invasive species; ornamental; population assignment; routes of invasion