UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Ecology and evolutionary biology of phenotypic plasticity in the threespine stickleback (Gasterosteus SPP.) Day, Troy Michael Charles


This work addresses questions concerning the evolution of diet-induced plasticity of trophic morphology in two species of freshwater threespine stickleback (Gasterosteus pp.). In chapter one I describe an experiment designed to answer the following questions about diet-induced morphological plasticity in these fish: (1) do the study species exhibit diet-induced morphological plasticity, and is this plasticity likely to be adaptive, (2) are different selective regimes associated with different degrees of plasticity, and (3) is there genetic variation for phenotypic plasticity in contemporary populations. The experiment revealed that these species exhibit plasticity that appears to be adaptive, and that an association exists between diet variability and the degree of diet-induced morphological plasticity as predicted by theory. It also revealed that genetic variation for morphological plasticity exists in both species. Chapter two presents a second experiment designed to further explore the possibility that diet variability can drive the evolution of morphological plasticity. This experiment also had three objectives: (1) to quantify the time scale of morphological change to determine if it is compatible with that of natural diet variability, (2) to explicitly examine the adaptive significance of diet-induced morphological plasticity by measuring its effect on foraging efficiency, and (3) to examine the effect that short-term learning (behavioural plasticity) has on foraging efficiency and compare its importance to that of morphological plasticity. This second experiment revealed that the time scale of plastic change is roughly compatible with that of diet variability and that diet-induced morphological changes result in changes in foraging efficiency. It also revealed that behavioural plasticity affects foraging efficiency but that it affects a different component of the prey ingestion process than does morphological plasticity.

Item Media

Item Citations and Data


For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.