Meeting Abstract
The causation of variation in avian timing of reproduction is ultimately rooted in its underlying physiology, as, after transduction and integration of cues, reproductive timing results from a cascade of neuro-endocrine processes. Current knowledge on the physiology underlying avian breeding time is still limited despite its importance as a key trait involved in how species adapt to climate change. This study assesses whether (individual) differences in egg-laying date can be explained by differences in candidate gene expression in a number of tissues and if so, whether these differences occur in the upstream (i.e. hypothalamus), or the downstream (ovary and liver) part of the neuroendocrine system. We used 72 female great tits from lines artificially selected for early and late laying, which were subjected to two contrasting temperature environments in climate controlled aviaries and sacrificed at three time points throughout the breeding season. For each organ for a set of candidate genes, known to be important or potentially important mediators of reproductive biology, individual gene expression levels were assessed using qPCR methods. Instead of analyzing candidate genes separately, we first conducted a Principal Component Analyses (PCA) per organ and subsequently analysed whether gene expression patterns differed in relation to egg-laying date, time point of sacrifice, and temperature treatment. A better understanding of individual gene expression patterns can contribute greatly to understanding the molecular evolutionary processes in natural populations, and the adaptive potential of species to adapt to environmental change.
