Environmental stressors have important influences on the ecological and evolutionary trajectory of populations through their effects on individual physiology, behaviour, and survival. Stress exposure can additionally have significant effects on offspring via "maternal effects", where the environment of the mother influences the traits and success of her offspring. For example, maternal stress exposes offspring to elevated maternal glucocorticoids (hormones released in response to stress). Elevated glucocorticoids during development can impact the offspring’s own endocrine physiology, with profound consequences for offspring behaviour, metabolism, and other processes. Ecologists have only recently begun to explore the effects of maternal stress in wild animals, but few studies have explored how these outcomes may vary across ecological contexts (for example, across different ecosystems, or in solitary versus group-living animals). A factor that is likely to be important in determining the outcome of maternal stress, is the post-natal social environment – whether offspring remain with their mother/parents, or not. This is because the social environment during early life can itself have substantial effects on offspring traits, with the potential to mitigate the outcomes of prenatal stress/exposure to glucocorticoids. However, the importance of the post-natal social environment in determining the outcomes of maternal stress remains unknown - this question forms the basis of project EGERNIALIZARDS.
How environmental stressors affect animal populations is an increasingly important question for society. Urbanisation, habitat loss, and human-induced climate change all pose significant stressors to wildlife. Better understanding how such stressors affect individuals, and what factors influence the outcomes of stress-exposure across generations, will aid us in better implementing and targeting effective conservation strategies. A better understanding of the outcomes of maternal effects across generations is also a key goal for evolutionary biologists in determining the relative role of genes versus the environment. We are currently ill-equipped to judge the extent to which these cross-generational effects can contribute to evolution (by influencing phenotypic diversity and/or differential survival in the offspring generation), as well as how environmental stressors (such as climate change and other anthropogenic effects) will influence species persistence. The extent of post-natal association with parents is a key source of variation between species; so, testing this question has the potential to reveal important large-scale patterns in the evolutionary importance of maternal effects, and species resilience in a changing world.
The overall objectives of the project EGERNIALIZARDS were to:
• experimentally test how the post-natal social environment influence the consequences of maternal stress for offspring, and identity potential physiological mechanisms;
• test the generality of maternal stress effects across species using a meta-analytical framework.
