Importance of Assessing Population Genetic Structure before Eradication of Invasive Species: Examples from Insular Norway Rat Populations

• Published in: Conservation biology 2005-10, Vol.19 (5), p.1509-1518
• Main Authors: ABDELKRIM, JAWAD, PASCAL, MICHEL, CALMET, CLAIRE, SAMADI, SARAH
• Format: Article
• Language: English
• Subjects: Animal migration; Animal, plant and microbial ecology; Applied ecology; Archipelagos; assignment test; Biological and medical sciences; biological invasion; Conservation biology; Conservation, protection and management of environment and wildlife; Ecological genetics; eradication unit; estructura poblacional; Evolutionary genetics; Fundamental and applied biological sciences. Psychology; Genes; Genetic loci; Genetics; Invasive species; invasión biológica; Islands; islas; marcadores microsatélite; microsatellite markers; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population genetics; Population structure; prueba de asignación; Rats; Rattus norvegicus; Rodents; unidad de erradicación
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1111/j.1523-1739.2005.00206.x

Determining the inter-island migration abilities of pest species and delimiting eradication units enable more viable long-term eradication campaigns because recurrent colonization from neighboring islands is avoided. We examined the genetic structure of the invasive Norway rat (Rattus norvegicus) to identify gene flow between islands and delimit population units at different geographical scales. We investigated variation in eight microsatellite loci in rat populations from 18 islands, representing five archipelagos off the Brittany coast (France). Although most of the islands are isolated from each other, short genetic distances, weak FST values between close islands, and a high level of cross-assignment showed that individuals collected on different islands could represent a single population unit. A Bayesian clustering method also supported the existence of high levels of gene flow between some neighboring islands. Thus, the statement "one island equals one population" can be false when inter-island distances are less than a few hundred meters. Genetic studies enable the definition of island clusters among which migration may occur that should be considered eradication units. To avoid reinvasion and to minimize ecological and economic costs, rats on all islands in an eradication unit should be eradicated simultaneously. We suggest that the genetic monitoring we performed here can be applied for management of any pest.