Le lundi 2 juin 2014 de 11h à 12h, Gabriel E. García-Peña (MIVEGEC – Centre IRD de Montpellier) présentera à la Tour du Valat (en grande salle) et en anglais un séminaire intitulé : “When species assemble rules a pathogen“. L’accès à ce séminaire est libre et sans incription.
Résumé
Amid rapid rates of environmental change and biodiversity loss, preserving human welfare requires understanding how ecosystems function. This endeavor calls for integration between ecology and health sciences to investigate the effects that eroding biodiversity may have on the emergence of zoonotic diseases. In the BIODIS project, we investigate the relationships between the presence of pathogens and diversity and assemble of species in communities. Current evidence suggests that assemble of species in a community may determine the number of individuals infected by a pathogen –i.e. prevalence. However, communities disassemble and assemble simultaneously by processes that are contingent on ecosystem type, taxonomic groups, life history strategies, and environmental and geographical contexts. Furthermore, most epidemiological studies neglect that communities are connected with other communities and may be influenced by processes at a higher level of organization as a metacommunity. Here, we investigate whether the relationships between diversity of species in aquatic communities and prevalence of the pathogenic bacteria (Mycobacterium ulcerans) are explained by processes of community assemble. We focus on three processes: (1) dispersal (connectivity between communities), (2) deforestation, and (3) nestedness and exchange of species at metacommunity level (Beta Diversity). M. ulcerarns exhibits both, symbiotic and free living stages in aquatic communities of Akonolinga in Cameroon, and produces a cutaneous necrotizing infection (Buruli ulcer) in humans that inhabit tropical rural areas prone to deforestation. Our analysis suggests that each aquatic community represents a random set of regional diversity and some include taxa not represented in the other communities. At this scale of study (75 km) connectivity in the hydric system plays a minor role driving prevalence of bacteria and diversity of species in the communities of rivers (lotic systems) and swamps and ponds (lentic systems). Furthermore, prevalence correlates positively to diversity in lotic systems, and negatively in lentic systems, buffering the effect of deforestation increasing prevalence. Together, our results support that the relationship between diversity and prevalence is contingent on the underlying processes driving diversity and species assembly in the communities, adding importance to researching the role of ecosystem function on pathogen ecology.
Quand la structure des communautés gouverne la dynamique d’un pathogène
Gabriel García-Peña, post-doctorant au sein de l’unité MIVEGEC de Montpellier, viendra nous présenter ses travaux concernant l’influence de la structuration des communautés aquatiques (incluant vertébrés et invertébrés) sur la dynamique de la bactérie Mycobacterium ulcerans au Cameroun. Ce pathogène est à l’origine de l’ulcère de Buruli, une maladie chronique débilitante de la peau pouvant entraîner des incapacités permanentes, qui touche principalement les enfants en Afrique subsaharienne. Cet exemple permettra d’illustrer l’approche générale qui pourrait être appliquée par la suite pour tenter de comprendre les éventuels liens entre l’évolution des communautés d’oiseaux en Méditerranée et les épidémies recensées aux abords des zones humides méditerranéennes depuis les années 1980.
