Date of Award


Degree Type


Degree Name



Earth and Environmental Sciences

First Advisor

Semeniuk, Christina

Second Advisor

Heath, Daniel


behaviour; gene transcription; invasive; range expansion; round goby




Range expansion of an invasive species can be influenced by intrinsic mechanisms such as behaviours described as being highly flexible and/or of specific behavioural types that are associated with dispersal ability. In addition, related gene transcription can also be influential in invasion success, promoting acclimation to novel environments. My study species, the round goby (Neogobius melanostomus), is an invasive fish continuously expanding its range in the Laurentian Great Lakes and its tributaries. This thesis aims to examine: 1) the behavioural repertoire of the round goby 2) differential gene transcription for gobies “natural” and environmental captive “treatment” using brain candidate genes associated with behavioural traits specific to aggression, boldness, stress response, learning, and activity; and 3) how behaviour and gene transcription vary between residents and dispersers and detection time since North American invasion. I found that round goby possess an “invasion behavioural phenotype” consisting of boldness, exploration, sociality and predator habituation. In addition, I found juveniles were bolder, explored more, were social and habituated to predation more compared to adults, but more so at established sites than recently invaded ones, contrary to predictions. Adults did not show any overall invasion stage differences, possibly due to conspecific densities, habitat-feature differences, and/or time-since-first detection. I showed evidence that there could be a genetic mechanism driving these behaviours, genes expressed for the “natural” group (aggression, stress-response, learning). My natural gene transcription results support that detection time can result in differences most likely driven by density, but round gobies are most likely able to produce “alternative ontogenies” due to plasticity, where individuals acclimatize to novel stressors over time, resulting in shifts in phenotypes. By examining all the facets that could drive range expansion one can gain a deeper insight underlying “invasiveness”.