Evolution of endocrine systems
Individual variation in endocrine traits
Understanding the mechanisms underlying life-history diversity is a major goal in evolutionary biology. Hormones participate in organizing life-stage transitions and can provide the mechanistic basis of individual
differences in reproductive behavior. Studying the magnitude and patterns of endocrine variation can uncover the mechanisms regulating the evolution of complex traits. We hope to characterize intra- and inter- individual variation in hormone levels, behavior, reproductive success, and survival in relation to the external environment for a detailed investigation of the endocrine traits that underlie life-history evolution.
We currently have 6 field sites along an urbanized gradient for a long-term field study on how hormonal regulation contributes to robustness and evolutionary persistence.
Plascity and adaptation
Glucocorticoids and life-history evolution
Animals live in changing environments. Phenotypic plasticity allows for rapid organismal adaptation to these environmental shifts. Thus, we investigate if intra-individual hormonal plasticity limit or promote evolutionary change.
We use common garden experiments to obtain individual reaction norms in response to changing conditions. We have a current breeding population of sparrows to examine whether physiological plasticity facilities or slows adaptation to novel environments.
Stress and urbanization
Physiological costs of living in an urbanized world
Animals and plants have evolved under a natural, daily light/dark cycle for millions of years. These cycles have been disturbed as nighttime darkness is increasingly replaced by artificial illumination on a large part of the planet, especially in industrialized and densely populated areas. In urbanized environments, we observe rapid, directional selection on certain physiological traits unlike fluctuating selection in natural environments. We study how organismal stress physiology relates to the degree and rate of urbanization. We use both field sites in the Netherlands and indoor aviaries to test the physiological response to artificial light. Our goal is to provide government agencies with management plans, such as using alternative lighting spectra, to combat large-scale ecological disruptions due to urbanization.
We are broadly interested in parental investment, especially with respect to sex and diet allocation. Avian parents sometimes show preferential treatment toward offspring of one sex. They may, for example, feed offspring of one sex more, or even selectively evict offspring of a certain sex from their nest. We have worked in the lab on zebra finches and in the field on nest selection in black noddies, to try and understand the dynamics of parental effort and parent/offspring conflict.