Signals of Survival: The Genetics and Ecology of Looking Dangerous

The seminar will take place on 12th of March, 11am at the SETE laboratory at Moulis.

ZOOM link : in preparation

Abstract

Warning signals provide a powerful system for understanding how phenotypic diversity arises—and why it persists—under natural selection. Because these traits advertise prey unprofitability to predators, theory predicts strong stabilizing selection for uniformity. Yet in many species, striking variation and stable polymorphism are maintained.

In my research, I use the wood tiger moth (Arctia plantaginis) as a model to explore this paradox. This chemically defended species produces volatile pyrazines to deter birds, displays warning coloration in both larval and adult stages, and exhibits substantial variation in signal appearance. In many populations, male hindwing colour is a discrete white–yellow polymorphism. Recent genomic work shows that this difference is associated with a duplication of a yellow-family gene, valkea, which is present and highly expressed in white morphs.

In this seminar, I will discuss how genetic architecture, predator communities, and sexual selection interact to shape the evolutionary trajectories of warning signals. Long-term field experiments and comparative data reveal that spatial variation in predator communities alters both the strength and direction of selection, consistent with a geographic mosaic of selection. Importantly, the genetic architecture underlying colour variation does not appear to impose strong pleiotropic constraints, suggesting that ecological context—rather than intrinsic genetic trade-offs—plays a central role in maintaining polymorphism.

Together, these results illustrate how integrating genetics and ecology allows us to move beyond the expectation of uniformity and toward a more nuanced understanding of how conspicuous signals evolve and persist in heterogeneous landscapes.

Biography

Johanna Mappes is Professor of Evolutionary Ecology at the University of Helsinki, Finland. Her research integrates behavioral ecology, evolutionary genetics, and field experimentation to understand how natural and sexual selection shape phenotypic variation in animal interactions.

She focuses particularly on predator–prey dynamics and the maintenance of color polymorphisms within and among populations. Using long-term field studies—most prominently in the wood tiger moth—combined with experimental and genomic approaches, her work examines how genetic architecture and spatially varying selection interact to maintain diversity in warning signals.

She has twice been appointed Academy Professor by the Academy of Finland. She is a member of the Finnish Society of Sciences and Letters and a Fellow of the American Academy of Arts and Sciences. She currently serves as Vice Dean for Academic Affairs in the Faculty of Biological and Environmental Sciences at the University of Helsinki and previously held a professorship at the University of Jyväskylä.

https://www.helsinki.fi/en/about-us/people/people-finder/johanna-mappes-9063368

Contact

If you would like to meet Johanna during her visit, please contact alexis.chaine@sete.cnrs.fr

antoine.chehere@inrae.fr