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Rost-Komiya, Beatrice

University of British Columbia

Little is known about how variation in functional traits affects the performance and ecological success of a population. Here, I investigate the importance of intraspecific variation and plasticity in two traits related to coping with environmental change: the cortisol-mediated stress response and whole-organism upper thermal tolerance. Using the Atlantic killifish (Fundulus heteroclitus) as an experimental model, I quantified variation between populations, between individuals, and within individuals in these traits. By analyzing video footage of northern and southern killifish after exposure to handling stress, I found evidence of differences in boldness and exploratory behaviour between populations, but no evidence for population differences in the behavioural response to stress. Behavioural differences between populations were associated with variation in the expression of a glucocorticoid receptor, GR1, in the liver between the two populations. Next, I used a repeated measures experiment to assess the extent of inter-individual variation in critical thermal maximum (CTmax) and determine whether it is a repeatable trait across different acclimation temperatures. I found significant inter-individual variation, and in accordance with other studies of repeatability in CTmax, I found high repeatability at a moderate acclimation temperature; however, acclimation to temperatures these fish experience in mid-summer in their natural environment resulted in a significant decrease in repeatability. Moreover, I found that CTmax was not repeatable across acclimation temperatures, which suggests that measures of the heritability of upper thermal tolerance are only relevant to the temperature at which they are determined. There was substantial inter-individual and intra-individual variation in plasticity of thermal tolerance, which could provide opportunities for adaptation in this trait. Taken together, these studies demonstrate that there is substantial intraspecific variation and plasticity in traits involved in responses to the environment, which has implications for how this species may respond to climate change.

Text

2022-03-09

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/80932

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/