Grant: Discovery Grants Program - Individual

Climate change is threatening global biodiversity as weather becomes warmer and more variable. Warming temperatures are now accompanied by large daily and seasonal temperature fluctuations exacerbating natural thermal variability. Ectothermic animals, like most fishes, are particularly vulnerable to increasing temperatures because all aspects of their biology are intimately controlled by their surrounding thermal environment. Both abiotic (e.g., oxygen) and biotic (e.g., sex, social context) factors influence this susceptibility to warming but we lack robust empirical data on the effects of many of these factors and/or their combination on thermal responses. In this proposal, the focus is on understanding the interaction between rising environmental temperatures and social behaviour in fishes. We recently demonstrated that a fish's social context influences how they respond to a sudden increase in temperature through changes in a thermal sensing ion channel. There is remarkable variation in social behaviour among and between species, including fishes and we do not know if the nature of social behaviour influences thermal sensitivity. Is social modulation of temperature sensation a broad phenomenon in fishes? To address this knowledge gap, my first objective will investigate these responses using a range of social behaviours (e.g., aggression, schooling) in three species of fish with distinct social lives. Modulation of a thermal sensing ion channel with sociality is novel and we do not yet know the underlying mechanism; however, there are compelling hormonal candidates. Thus, my second objective will test the hypothesis that the stress hormone, cortisol, is involved in thermal sensor modulation. It is likely that the increasing frequency of unpredictable and more extreme temperatures, as opposed to gradual temperature increases, will drive evolutionary responses to climate change. We know that temperature strongly influences social behaviour in fishes; yet we know relatively little about how key social traits will be affected by this unpredictable, natural variation. We will investigate the effects of warm, diel thermal fluctuation on social behaviour and temperature resilience in my third objective. We will use creative approaches and techniques to address these objectives ranging from the whole animal to the molecular. The funding requested will allow me to train students who will gain technical and transferable skills, invaluable for diverse scientific careers. Given predicted climate change scenarios, we need to understand factors influencing species' capacity to respond to thermal heterogeneity and what tools they possess to overcome (or not) these thermal challenges. This novel research is expected to have broad and fundamental impact by significantly advancing our mechanistic understanding on how ubiquitous animal interactions affect responses to ecologically relevant warming.