Vivien Louppe soutenance de thèse intitulée "Dispersion et adaptation de deux carnivores sauvages envahissants aux Antilles, le raton laveur et la petite mangouste indienne"
Vendredi 17 Juillet à 14h00, à l'Amphi Rouelle.
En raison du nombre limité de personnes dans la salle, nous enverrons bientôt un lien pour suivre la soutenance en vidéo.
Composition du jury
M. Daniel Simberloff, Professor, University of Tennessee, Knoxville, USA - Rapporteur
M. James Russell, Associate Professor University of Auckland, Auckland, NZ - Rapporteur
Mme. Elsa Bonnaud, Maitre de Conférence, Université Paris-Sud, Orsay - Examinatrice
M. Anthony Herrel, Directeur de Recherche, Muséum National d’Histoire Naturelle, Paris - Examinateur
Mme Géraldine Veron, Professeur, Muséum National d’Histoire Naturelle, Paris - Directrice de thèse
Ecosystem disruption through the introduction of exotic species is a major driver of the erosion of global biodiversity. Insular ecosystems, including many biodiversity hotspots, are particularly threatened by biological invasions. Illustrating this global trend, the Caribbean region has experienced a major decline in
biodiversity as a consequence of the different waves of human colonisation and the concomitant increase of non-native species introductions. Notably, two wild carnivores have been introduced in the Caribbean during the 17th and the 19th century: the northern raccoon, Procyon lotor, and the small Indian mongoose, Urva auropunctata. However, the understanding of the introduction history, as well as the environmental factors that may influence their distribution, remain largely incomplete. In this thesis, DNA analyses shed light on the geographical origins of the introduced populations of northern raccoon and small Indian mongoose in the Caribbean. While Bahamas populations of northern raccoon originated from two different sources in Florida, the Lesser Antilles populations were most probably introduced from the north-eastern regions of the species’ native range. Our genetic analyses of invasive populations of small Indian mongoose confirmed several introduction events reported in historical records, but also shed new light on the dispersal of the species in the Caribbean
region, suggesting new introduction scenarios for populations whose historical records were missing or incomplete. Furthermore, microsatellite data revealed a strong structuration of the populations within the West Indian islands, highlighting that expansion between nearby islands appears highly dependent on human
intervention. Influence of environmental factors on the distribution of both species was investigated at the global and the Caribbean scale. Environmental niche modellings revealed broad geographical areas climatically favourable for the northern raccoon and the small Indian mongoose at a global scale. Moreover, predictions for 2050 showed wide newly favourable areas north of their current favourable regions, particularly in Europe, where populations of both species are currently expanding. At a more local scale, our survey and modelling highlighted the capacity of the northern raccoon and the small Indian mongoose to cope with a high diversity of habitats in the Caribbean islands. Moreover, spatiotemporal co-occurrence with other bird and mammal species revealed that both species face few or no competitors in these insular ecosystems. Finally, our investigation of the variation in head morphology in the small Indian mongoose revealed significant differences in size and shape, of both cranium and mandible, between the continental native and the insular invasive populations. Native individuals showed smaller crania and mandibles, and crania appeared thinner and more elongated. Our statistical analyses revealed that, rather than being related to changes driven by ecosystem structure, morphological variations in introduced populations may reflect the introduction history of the species.
This research project represents an important step toward a better understanding of the biological and ecological mechanisms underpinning the successful introduction, establishment and spread of the northern raccoon and the small Indian mongoose outside their natural boundaries.