Staff members: Kamiel Spoelstra (NIOO), Serge Daan (U Groningen), Andrew Loudon (U Manchester), Martin Wikelski (Max Planck Institute of Animal Behaviour).
Hormones are powerful interal signals. They have pleiotropic effects on behavior, physiology and morphology and regulate major transitions between phases of the annual cycle in animals. These actions make hormones ideal candidates for mediating life history trade-offs. Are these trade-offs present, and regulated by similar physiological pathways in different populations, or have there been evolutionary changes in the linkage between hormones and traits such that hormones might mediate trade-offs in different ways in different populations? Using descriptive and experimental approaches we are exploring the linkage between the hormones testosterone and corticosterone with behavior and physiology in various bird species that differ in crucial aspects of their life history. We are conducting these studies in the context of several theories on the evolutionary linkage between hormones and traits (for example see Fig below).
In egg-laying species, mothers deposit hormones like androgen, glucocorticoid and thyroid in their eggs. It is widely assumed that they adjust the concentration in response to environmental and social cues to optimize their own fitness and/or that of their offspring. In a comprehensive meta-study of 19 different bird species, it has now been shown that these assumptions are statistically unfounded. There is no discernible effect of androgens, glucocorticoids and thyroid hormones on either maternal or offspring fitness. This challenges previous assumptions and is an important theoretical contribution to the field.
Mentesana L, Hau M, D'Amelio PB, Adreani NM, Sánchez-Tójar A. 2025. Do Egg Hormones Have Fitness Consequences in Wild Birds? A Systematic Review and Meta-Analysis. Ecology Letters 28: e70100.
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In this paper, we explore how mitochondrial aerobic metabolism influences different aspects of organismal performance, such as through changing adenosine triphosphate (ATP) and reactive oxygen species (ROS) production. We consider how such insights have advanced our understanding of the mechanisms underpinning key ecological and evolutionary processes, from variation in life-history traits to adaptation to changing thermal conditions, and we highlight key areas for future research.
Kasja Malkoc, Lucia Mentesana, Stefania Casagrande, and Michaela Hau, “Quantifying glucocorticoid plasticity using reaction norm approaches: There still is so much to discover!," Integrative and Comparative Biology 62 (1), 58-70 (2022).
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