Neglected aspects of hormone mediated maternal effects: Studies on early embryonic modulation of maternal hormonal signals in avian eggs and related methodological aspects

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Vertebrate embryos are exposed to maternal hormones, possibly mediating maternal effects (hormone mediated maternal effects), which can have consequences for the offspring phenotype. Egg laying species have been used extensively to study such effects as the embryo develops inside the egg, where the mother deposits her hormones, facilitating experimental manipulations of this exposure without interfering with the mother. Bird species are a particularly suitable model since bird ecology is often well-known and can easily be studied in the field, facilitating studies of the adaptive significance of maternal effects.
Several studies have injected hormones into bird eggs, mimicking hormonal variation in egg yolk, and found a wide array of effects on morphology, physiology and behaviour of the offspring. This suggests that the mother is able to adjust the offspring phenotype (adaptively) to the current environment via her hormones, but the underlying mechanisms are unknown, importantly (i) the maternal hormone allocation is often not determined correctly, and (ii) the embryo is often seen as a passive responder and assumed to be a ‘slave’ to the maternal signals, but its actual role in translating maternal hormonal signals in proximate and ultimate manners is poorly understood.
In this thesis I report the findings on some of these neglected aspects and discuss their potential implications in eco-evolutionary explanations of hormone mediated maternal effects. This work is thought to stimulate further research for integrating proximate and ultimate approaches towards understanding the functions of maternal hormones.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
  • Groothuis, Ton, Supervisor
  • Gahr, M., Supervisor, External person
Award date2-Dec-2019
Place of Publication[Groningen]
Print ISBNs978-94-034-2162-9
Electronic ISBNs978-94-034-2161-2
Publication statusPublished - 2019

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