Ana MORAN – PhD defense

PhD defense in english

Zoom link coming soon

Team : IVEP

Supervisor : Jacques Gautrais (CRCA-CBI)

Committee members :

• Dr. Simon Benhamou – CEFE, Montpellier – Reviewer
• Dr. Carmen Bessa-Gomes – AgroParisTech, Paris – Reviewer
• Pr. Richard Fournier – LaPlace, Toulouse – Examiner
• Pr. Frederic Bartumeus – ICREA, Spain – Examiner
• Dr. Jacques Gautrais – Research Center on Animal Cognition, Toulouse – Thesis supervisor
• Dr. Alfonso Pérez-Escudero – Research Center on Animal Cognition, Toulouse – Guest
• Dr. Mathieu Lihoreau – Research Center on Animal Cognition, Toulouse – Guest

Abstract :

Understanding how pollinators move across space is key to understanding plant mating patterns. Bees are usually assumed to search for flowers randomly or using simple movement rules so that the probability of discovering a flower depends primarily on its distance to the nest. However, experimental work shows this is not always the case.

Until now, no one has successfully enunciated a realistic model of bee movement that considers the fact that they are Central Place Foragers and thus they start and end all their movements in the same place: the nest.

To further our knowledge of the exploratory movement of central place foraging bees, I propose a model of central place foraging that produces realistic bee trajectories by accounting for the autocorrelation of the bee’s angular speed, the attraction to the nest (homing), and Gaussian noise.

The four parameters of this model have been tuned based on experimental trajectories collected on bumblebees (Bombus terrestris) in the field. The model not only has the potential to describe the movement patterns of bees but also those of other central place forager animals.

The proposed model paves the way to compute theoretical predictions about pollination in the field. Here, I explored the statistics of flower discovery, depending on flower patch sizes and densities.

Simulations of bumblebee trajectories highlight two effects that were previously overlooked: a masking effect that reduces the detection of flowers close to another and a scale effect that modulates this first effect as a function of the distance between flowers.

At the plant level, flowers distant from the nest were more often discovered by bees in low-density environments. At the colony level, foragers found the most flowers when they were small and at medium densities. These results suggest that pollination would be optimized in a range of intermediate flower densities: when the density is too low, few flowers are discovered; when the density is too high, flowers distant from the nest become masked by closer ones (due to the masking effect).

These results indicate that the processes of search and discovery of resources are potentially more complex than usually assumed, and question the importance of resource distribution and abundance on bee foraging success and plant pollination.

© Crédit photo: Romain Hacquet – @aker.romain