Dr. Lucie Froissart

Research interests

I am interested in behavioural ecology and animal cognition. More precisely, I study how animals perceive, process and use information, including past information, in an evolutionary perspective.
During my PhD in Lyon (France), I focused on past information use, learning and memory.
First, we studied how, in the context of host patch exploitation, the parasitoid wasp Venturia canescens manages successive past information sources and redundant ones. We showed that the wasps seemed to weight equally information pieces coming from older and more recent host patches successively foraged. Given the pace of host density variations in the environment, such a process should allow the wasps to estimate more accurately the current environment profitability. Moreover, among three interdependant cues of patch richness (the time invested, the level of host odour concentration and the number of eggs laid on former patches), all being perceived by the wasps, only the number of eggs laid appeared to be used by the wasps as a past information source. This result could indicate that the number of eggs laid on previously exploited patches is a more reliable cue of environment profitability than both other cues.
Second, we tested the hypothesis that features of learning and memory evolved in response to ecological constraints. We conducted a comparative study with arrhenotokous and thelytokous* V. canescens, each reproductive mode thriving in a specific habitat. Results obtained through olfactory conditioning partially matched our initial predictions; this supports the idea of a link between resource distribution and learning features. We also tested this hypothesis through a modelling work: the question was to know if the length of the different phases that compound memory could be shaped by environmental constraints. Indeed, great differences in the duration of the different memory phases are observed, even in closely related species. We found that an optimal length of a short-term-memory (STM) like module could rise, relatively short in most of the cases, and that this optimum depended on the resource spatial distribution and on the precise functional roles given to each memory module. Moreover, the rise of an optimal STM length was not attributable to physiological constraints, what emphasises the fact that ecological constraints may play a major role in the evolution of memory phases, and that the understanding of the precise role of each memory phase should shed light on the understanding of that evolutionary process.

The aim of the project at the DEE is to seek how cognitive abilities, from perception to learning, could have evolved in larvae of Drosophila melanogaster under an experimental evolution process. Since more than 150 generations, these flies are indeed submitted to malnutrition (diluted food but no crowding) at the larval stage. The work already done on those larvae have shown that some of their life history traits as well as some features of their behaviour have evolved. The idea is here to study how changes in information processing can allow the fly larvae to cope with this chronic nutritional stress.

*in arrhenotokous wasps, males arise from unfertilised eggs and females from fertilised eggs; thelytokous wasps only produce females through parthenogenesis.

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lucie.froissart[@]unil.ch 

Member of Kawecki group

Biophore - CH-1015 Lausanne
Switzerland
Tel. +41 21 692 41 60
Fax +41 21 692 41 65