Sources of variation in phenotypic plasticity across ectoterms

Abstract

Anthropogenic changes including pollution, artificial light-at-night, and climate change can influence physiological and ecological functions at all levels of organisation. The aim of this thesis was to investigate the consequences of these anthropogenic drivers on ectotherms and understand the factors that undermine compensatory responses. A fully factorial experiment was conducted to determine the interactive effects of chemical pollution and artificial light-at-night on physiological performance. Meta-analyses were also conducted to determine the difference in phenotypic traits and their plastic responses between constant and fluctuating thermal environments, and the extent of population-level differences in the capacity for phenotypic plasticity. Here, we found that BPS exposure, but not photoperiod, had an inhibitory effect on metabolism and swimming performance in zebrafish (Danio rerio). However, there was no interactive effect between plastic pollution and artificial light. The thesis also shows that phenotypic responses of ectotherms to thermal change is mostly driven by long-term mean temperatures, and only in certain contexts by temperature fluctuations particularly at high amplitudes. Negative consequences of extreme fluctuations did not affect plastic responses, and the capacity for phenotypic plasticity was not different in constant and fluctuating thermal environments. Lastly, it was found that there are differences in the capacity for phenotypic plasticity among populations of the same species. The disparity between populations was particularly evident in physiological responses, and in the developmental plasticity of morphological traits. The work presented in this thesis advances our understanding of the impacts of anthropogenic changes and the factors that influence the compensatory responses of ectotherms, which can have implications for conservation and management of natural resources.