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Importance of an evolutive approach for the study of blological invasions. The example of ragweed invasion in the Rhone valley

Benjamin Genton 
Abstract : Biological invasions have major ecological and economic consequences. Demographic, ecological and genetic mechanisms involved in bioinvasions are well known, but predicting invasions is still impossible. Approaches exploring the ecological characteristics of invaders or invaded environment do not converge to a unifying pattern. Here, we support an alternate, evolutionary approach that investigates two paradoxes: (1) How can some species succeed in an environment different from the one they are adapted to, sometimes displacing native species that should a priori be more adapted to the local conditions? And (2) how can exotic species adapt so rapidly to new conditions despite founder effects? North American common ragweed (Asteraceae) is an invasive species in the Rhône valley in France. This weed poses major health problems since its pollen is a strong allergen. To solve the two paradoxes, we conducted different studies comparing French invasive and North American native populations. We found that French populations may be advantaged by an herbivore pressure release. However, we detected no adaptation consecutive to this enemy release. Moreover, we showed that French populations were more diverse than North American ones, using microsatellites markers that were developed for this study. Introductions from multiple source populations seem to have limited founder effects. Finally, we propose a theoretical evolutionary framework that distinguishes three invasion types: those that require no change in environment or species, those that arise as a consequence of an environmental change and those that result from species adaptation.
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Submitted on : Tuesday, June 27, 2006 - 8:00:00 AM
Last modification on : Tuesday, June 27, 2006 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 7:18:02 PM


  • HAL Id : pastel-00001764, version 1



Benjamin Genton. Importance of an evolutive approach for the study of blological invasions. The example of ragweed invasion in the Rhone valley. Life Sciences [q-bio]. ENGREF (AgroParisTech), 2005. English. ⟨pastel-00001764⟩



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