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Utilisationdel'espaceparleratonlaveuret Lamoufetterayée,Deuxprincipauxhôtes D'unvariantduvirusdelarage

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Utilisationdel'espaceparleratonlaveuret Lamoufetterayée,Deuxprincipauxhôtes D'unvariantduvirusdelarage Utilisation de l’espace par le raton laveur et la moufette rayée, deux principaux hôtes d’un variant du virus de la rage Thèse Olivia Tardy Doctorat en biologie Philosophiae Doctor (Ph.D.) Québec, Canada © Olivia Tardy, 2016 Résumé Comprendre les mécanismes comportementaux qui régissent la transmission et la propagation de pathogènes est critique pour les programmes de contrôle et de prévention des maladies infectieuses. Ma thèse explore le lien entre l’hétérogénéité des paysages agroforestiers et la répartition spatio-temporelle du raton laveur (Procyon lotor) et de la moufette rayée (Mephitis mephitis), deux principaux hôtes du variant de la rage du raton laveur. Pour cela, j’ai étudié les processus de sélection densité-dépendante de l’habitat à large et fine échelles spatiales, ainsi que les mécanismes de connectivité fonctionnelle chez ces deux espèces. Le chapitre 1 a révélé qu’à faibles abondances de congénères, les ratons laveurs sélectionnaient les secteurs avec une forte proportion de forêts, tandis que les moufettes rayées préféraient les zones avec une large proportion de milieux anthropiques. À fortes abondances, cependant, les deux espèces sélectionnaient plutôt les secteurs composés d’une forte densité de bordures maïs-forêts et forte proportion de champs de maïs. Le chapitre 2 a montré que la sélection des champs de maïs par les ratons laveurs dépendait à la fois de la densité de congénères et de l’abondance des champs de maïs. Dans le chapitre 3, j’ai développé un modèle spatialement explicite basé sur l’individu pour évaluer comment des règles empiriques de déplacement font émerger des patrons de contacts chez des individus hôtes. Les simulations ont révélé trois patrons généraux dans les taux de contacts. Premièrement, une petite portion de ratons laveurs simulés était responsable de la majorité des contacts dans les paysages virtuels. Deuxièmement, les taux de contacts des ratons laveurs simulés augmentaient linéairement avec la densité de congénères plutôt qu’avec la proportion de congénères dans la plupart des paysages. Troisièmement, l’effet de la connectivité fonctionnelle sur les taux de contacts variait fortement en fonction des types de milieux et de leur disponibilité dans le paysage. Les modèles développés dans cette thèse procurent une base solide au développement de programmes de contrôle et de prévention des maladies infectieuses, en permettant d’identifier les zones à hautes densités d’individus et de taux de contacts entre eux, et donc où le risque de transmission de pathogènes est relativement élevé. iii Abstract Understanding behavioral mechanisms that determine the transmission and spread of pathogens is critical for control and prevention programs of infectious diseases. My thesis investigates the interplay between the heterogeneity of agriculturally fragmented landscapes and spatio-temporal distribution patterns of raccoons (Procyon lotor) and striped skunks (Mephitis mephitis), two main hosts of the raccoon rabies virus variant. To do this, I studied the processes of density-dependent habitat selection at large and fine spatial scales, together with the mechanisms determining functional connectivity for these two species. The first chapter revealed that at low conspecific abundances in the landscape, raccoons selected areas with a high proportion of forests, whereas striped skunks preferred areas with a large proportion of anthropogenic features. At high conspecific abundances, however, both species rather selected areas composed of a high density of corn-forest edges and a large proportion of corn fields. The second chapter showed that raccoons altered their selection of corn fields depending upon both conspecific density and abundance of corn fields. In the third chapter, I built a spatially explicit individual-based model to assess how empirical movement rules translate into spatial patterns of contact rates among individual hosts. The simulations revealed three general patterns in contact rates. First, a small number of simulated raccoons were responsible for the majority of contacts in virtual landscapes. Second, contact rates of simulated raccoons increased linearly with conspecific density rather than with the proportion of conspecifics in most of the virtual landscapes. Third, the influence of functional connectivity on contact rates varied strongly among land cover types and with their availability in the landscape. The models developed in this thesis provide a strong basis upon which to build control and prevention programs for infectious diseases, as they identify areas where animal density and contact rates should be relatively high and, hence, where the risk of pathogen transmission should also be high. v Table des matières Résumé .................................................................................................................................. iii Abstract .................................................................................................................................. v Table des matières .............................................................................................................. vii Liste des tableaux ................................................................................................................. xi Liste des figures .................................................................................................................. xiii Remerciements .................................................................................................................. xvii Avant-propos ...................................................................................................................... xix INTRODUCTION GÉNÉRALE ......................................................................................... 1 1. Relation entre la densité de populations hôtes et la transmission d’agents pathogènes . 2 2. Impact des perturbations anthropiques sur la transmission et la propagation d’agents pathogènes .............................................................................................................................. 5 3. Composition, structure, connectivité du paysage et relations hôtes-pathogènes ............ 7 3.1. Composition et structure du paysage ....................................................................... 7 3.2. Connectivité du paysage .......................................................................................... 8 3.2.1. Théorie des métapopulations ............................................................................ 9 3.2.2. Connectivité structurelle ................................................................................. 10 3.2.3. Connectivité fonctionnelle .............................................................................. 11 4. Répartition spatio-temporelle des populations hôtes .................................................... 12 4.1. Sélection de l’habitat .............................................................................................. 12 4.1.1. Sélection de l’habitat dépendante de la densité de congénères ...................... 13 4.1.2. Sélection de l’habitat dépendante des ressources ........................................... 17 4.2. Déplacements entre des parcelles d’habitat ........................................................... 19 5. Modélisation de la transmission et de la propagation d’agents pathogènes ................. 20 6. Objectif et organisation de la thèse ............................................................................... 22 7. Modèles d’étude: le raton laveur et la moufette rayée .................................................. 23 CHAPITRE 1 ...................................................................................................................... 27 Résumé .................................................................................................................................. 29 Abstract ................................................................................................................................. 31 1. Introduction ................................................................................................................... 33 2. Materials and Methods.................................................................................................. 35 2.1. Random resampling across the survey area ........................................................... 35 2.2. Replication ............................................................................................................. 39 2.3. Isodar theory ........................................................................................................... 39 2.4. Case study .............................................................................................................. 41 2.4.1. Ethics Statement ............................................................................................. 41 2.4.2. Survey areas and captures of raccoons and striped skunks ............................ 41 2.4.3. Resampling procedure .................................................................................... 42 2.4.4. Measures of landscape composition and structure ......................................... 43 2.4.5. Statistical analysis ........................................................................................... 44 3. Results ........................................................................................................................... 46 4. Discussion
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