PhD defense of samantha Aguillon on December 15th 2023

Samantha AGUILLON defended her PhD thesis on Friday, December 15, 2023, at 4 p.m. in the Elie amphitheater at the University of Reunion Island.

The role of ecology and population dynamics of the Reunion Free-tailed bat in the circulation of infectious agents.

Abstract: Bats are fascinating mammals because of their great specific and morphological diversity, as well as for their ability to harbour and tolerate viruses that can cause epidemics in humans. Nowadays, an increasing number of diseases are emerging around the world and the ecological processes influencing the circulation of infectious agents in natural hosts, like bats, remain poorly understood. Using the Reunion free-tailed bat (Mormopterus francoismoutoui) and three of its infectious agents (paramyxovirus, herpesvirus and Leptospira bacteria) as a study model, we analysed how the ecology and population dynamics of bats influence the transmission of infectious agents. Based on field monitoring of bat populations, we first characterized the phenology of the Reunion free-tailed bat and highlighted marked seasonal variations of roost size and of composition according to age, sex and reproductive status. These results allowed us to propose a new reproductive cycle for this species endemic to Reunion Island. Using phylogeny and population genetics based on wing punch samples, we studied and dated the colonization events of the island, and also showed the in situ diversification of this species with the evolution of ancestral lineages, co-existing nowadays in sympatry within a metapopulation. Finally, the spatio-temporal analysis of the infection at the scale of the population (roosts) and individuals (via bat recaptures) suggests that paramyxoviruses and Leptospira bacteria (excreted in urine), and herpesviruses (excreted in saliva), all establish persistent infections with intermittent excretion. Our analyses highlight that reproduction in females (gestation), but also in males (mating), as well as age and the interactions between infectious agents, are major determinants of seasonal excretion dynamics. Thus, the eco-epidemiological approach used here provides valuable information to better predict, in the future, how bats respond to ecosystem disturbances and the cascading consequences on infections and the risks of emerging zoonoses.

Keywords: bats, tropical island, phenology, genetic structure, infection dynamic

Members of the jury
Pr. Christophe Thébaud (Université de Toulouse)
Pr. Jordi Serra-Cobo (Université de Barcelone)
Dr. Carine Brouat (IRD, Montpellier)
Dr. Emmanuelle Robardet (ANSES, Nancy)
Dr. Patrick Mavingui (CNRS, La Réunion)
Dr. Muriel Dietrich (IRD, La Réunion)