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Participants: Prof William A. Buttemer (PI), Dr Katherine L Buchanan, Dr BriAnne Addison
Aims and background: Successful environmental adaptation involves not only selection on the genotype, but physiological priming through epigenetic effects. Birds represent excellent organisms to test such effects as their reproductive investment can be quantified in terms of egg quality, prior to hatching. There is ample evidence of maternal condition at the time of egg laying significantly affects the phenotypic traits of offspring. This can arise through variations in the amount of yolk allocated to eggs, but more subtly through variation in maternal hormones that, in turn, become incorporated into the yolks and albumen of eggs. Because maternal steroids are lipophilic, they are easily transferred to yolking follicles prior to ovulation. Studies have shown that breeding females experiencing raised levels of corticosterone during exposure to adverse conditions will form eggs with elevated corticosterone content, through passive transfer. There is increasing evidence that chicks hatched under such conditions are phenotypically distinct from chicks from less-stressed mothers, often showing reduced immunoreactivity and long-term behavioural modification that makes them more shy and tentative when encountering novel situations. This has prompted suggestion that elevated corticosterone levels in stressed mothers pre-condition their offspring to better cope with hostile environments. While such attributes might be beneficial in the short term, questions remain as to how long such traits persist and how they affect subsequent generations of progeny. This project will explore these questions by experimentally manipulating maternal corticosterone levels during egg laying and examining a battery of physiological, endocrinological, immunological, and behavioural consequences of chicks and their consequent progeny over multiple generations.
Scientific significance and innovation: This is the first study to test the hypothesis that environmental stress primes offspring phenotype in an adaptive manner through corticosterone deposition in the egg. Further, this study will apply a wide-range of pertinent measurements to assess the consequences of avian maternal stress across multiple generations. This has fundamental importance for quantifying the fitness consequences of short-term stress in breeding birds and, thus, to gain insight into the costs and benefits of maternal transfer of glucocorticoid hormones into eggs.
Potential national benefit and strategic alignment with the aims of the CIE: This research complements the CIE's objective of using integrative approaches in addressing questions of ecological and evolutionary relevance. National benefits include: advancing intellectual and scientific development of the PhD candidate; gaining insight into maternal stress effects on offspring quality which is highly pertinent to evolutionary and conservation biology.