Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird

• DOI: 10.1371/journal.pone.0009743
• Publication Date: 2010-03-16T22:16:11Z
• Authors: Eric Lombaert; Thomas Guillemaud; Jean-Marie Cornuet; Thibaut Malausa; Benoît Facon; Arnaud Estoup
• Keywords: Approximate Bayesian Computation; Alien species

Recent studies of the routes worldwide introductions alien organisms suggest that many widespread invasions could have stemmed not from native range, but a particularly successful invasive population, which serves as source colonists for remote new territories. We call here this phenomenon bridgehead effect. Evaluating likelihood such scenario is heuristically challenging. solved problem by using approximate Bayesian computation methods to quantitatively compare complex invasion scenarios based on analysis population genetics (microsatellite variation) and historical (first observation dates) data. applied approach Harlequin ladybird Harmonia axyridis (HA), coccinellid Asia was repeatedly introduced biocontrol agent without becoming established decades. show recent burst HA followed scenario, in an eastern North America acted invaded European, South American African continents, with some admixture strain Europe. This demonstration mechanism via has important implications both theory (i.e., single evolutionary shift versus multiple changes case populations independently) ongoing efforts manage heightened vigilance against bridgeheads).