Karolina Argote's thesis "Microarthropod Responses to Habitat Fragmentation: Laboratory Experiments in Artificial Landscapes".

Mrs. Karolina Argote, doctoral student at UMR IMBE, Populations, Landscapes, Communities & Conservation teamwill publicly defend his thesis on Tuesday 18 March 2025 at 2pm in the Amphi Marion, Bâtiment 5, Campus St Charles.

In front of a jury made up of :

• Marc CADOTTE, Rapporteur, University Professor, University of Toronto
• Patrick LAVELLE, Rapporteur, Professor Emeritus, Paris Sorbonne University
• Stéphanie MANEL, Examiner, HDR Research Director, CEFE Montpellier
• Thomas TULLY, Examiner, Senior Lecturer, Sorbonne University
• Virginie BALDY, Chair of the Jury University Professor, Aix-Marseille University, IMBE
• Cécile ALBERT, Thesis supervisor, HDR Research Director, CNRS
• Mathieu SANTONJA, Thesis co-supervisor, Senior Lecturer, Aix-Marseille University, IMBE
• Benoît GESLIN, Thesis co-supervisor, Senior Lecturer HDR, University of Rennes, ECOBIO

Summary of work:

This doctoral thesis studies how habitat fragmentation influences the persistence of populations of a springtail, Folsomia candidathrough an experimental approach using artificial mini-landscapes monitored in the laboratory.

First, we analyse how the quality of resources and the distance between habitat tasks influence the foraging behaviour and demography of F. candidaWe then examine how different habitat configurations and matrix qualities affect the survival and movements of springtails. We then examine how different habitat configurations and matrix qualities affect the survival and movements of springtails. The results show that the amount of accessible habitat, including the distance between habitats and the strength of the matrix, is a good predictor of population size and extinction risk. Survival during movement through the matrix proved to be a key mechanism, influencing colonisation rates and demographic stability while limiting access to distant patches.

We then evaluate the effectiveness of connectivity elements, such as corridors and stepping stones, in promoting dispersal and population persistence in highly rough matrices. We found that hostile matrices amplified the risks associated with dispersal, creating a trade-off between colonisation and population size. Although connectivity generally facilitated colonisation and increased reproduction in new patches, its effectiveness depended on the distance between patches. In particular, increased dispersal also resulted in higher mortality, leading to overall smaller populations in connected landscapes than in unconnected landscapes.

Overall, my thesis highlights the need to explicitly integrate landscape matrix resilience into conservation strategies and the effects of landscape features on population dynamics. By experimentally quantifying the combined effects of matrix strength and habitat configuration, this work emphasises the importance of incorporating these factors into connectivity models and conservation planning, offering practical solutions for managing and landscaping fragmented landscapes and restoring ecological connectivity.

Key words : configuration of the habitat, resistance of the matrix, accessibility of the habitat, Folsomia candidafragmentation, connectivity.