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A major breakthrough in invasion biology is the consideration that range expansion brings into play a set of evolutionary forces at the front that apply differential selection on life-histories. It is critical in univoltine defoliators that typically require synchronization with their host and reaching a resistant stage before winter. Maintaining synchronizations across climatic gradients is by no means trivial in ectotherms whose growth rates directly depend on climatic variations. We will tackle this issue in the winter moth Operophtera brumata thanks to its well-documented northward expansion through Fennoscandia since the 1900s. Development of this cyclically outbreaking geometrid is constrained by phenological boundaries varying over years and along its range. Several melanic forms of larvae locally coexist, with positive density-dependence of the frequency of dark larvae, but their adaptive significance is still unknown. Camouflage advantage on defoliated trees has been rejected, while costs on survival and enemy avoidance have been demonstrated. This is hard to reconcile with the sustained polymorphism, suggesting benefits to offset the survival handicap. We suspect that melanism may alter their development rate by modulating susceptibility to solar radiation, especially under northern Fennoscandia latitudes with permanent daylight during summer. Variations in melanism have long fostered curiosity of thermal biologists, may be spatially structured to cope with phenological constraints along climatic gradients, and may yield local heterogeneity as a bet-hedging strategy to ensure phenological matching. Natural phenological and phenotype monitoring will be combined with respiratory assays and state-of-the-art metabolomics to test whether increased melanism provides increased growth rates. Untangling spatio-temporal heterogeneity of polymorphism will help assessing if it facilitates ongoing expansion and adequate phenology in a wider variety of climates.
My research interests lie in the relationship between the long-lasting success of range expanding (and/or invasive) species and their ability to cope with the dynamic nature of the selection regimes they face in recipient environments. Theory and experimental work indicate that inter-individual heterogeneity can strongly impacts eco-evolutionary dynamics during range shifts and biological invasions. Recent advances in Invasion biology show that pioneer individuals are most likely not a random subset of core populations, but rather are more successful in neo-colonized areas thanks to a suite of traits that increase the probability to (i) reach remote sites, (ii) circumvent more stringent conditions and/ or (iii) secure fitness beyond the historic range. A focus of my research was to produce insights on the phenotypic responses that occur over time and space during range expansions and lead to differentiation of populations with different residence times. Responses span from physiological to morphological and behavioral changes, encompass plastic and evolutionary processes, and trigger success and spread under the new conditions individuals are subjected to.
Renault D., Laparie M., McCauley S.J. & Bonte D., 2018. Environmental adaptations, ecological filtering, and dispersal central to insect invasions. Annual Review of Entomology 63, 345-368.
Laparie M., Vernon P., Cozic Y., Frenot Y., Renault D. & Debat V., 2016. Wing morphology of the active flyer Calliphora vicina (Diptera, Calliphoridae) during its invasion of the Kerguelen Islands, a sub-Antarctic archipelago where insect flightlessness is the rule. Biological Journal of the Linnean Society 119, 179-193.
Robinet C., Laparie M. & Rousselet J., 2015. Looking beyond the large scale effects of global change: local phenologies can result in critical heterogeneity in the pine processionary moth. Frontiers in Physiology 6, 334. Doi: 10.3389/fphys.2015.00334.
Laparie M., Renault D., Lebouvier M. & Delattre T., 2013. Is dispersal promoted during range expansion of invasive species? Morphological analysis of a ground beetle invading the Kerguelen Islands, Merizodus soledadinus (Coleoptera, Carabidae). Biological Invasions 15, 16411648.
Colinet H., Larvor V., Laparie M. & Renault D., 2012. Exploring the plastic response to cold acclimation in Drosophila melanogaster through metabolomics. Functional Ecology 26, 711-722.