|Wolters, William - Bill|
Submitted to: Experimental Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/2/2012
Publication Date: 3/1/2013
Citation: Anttila, K., Dhillon, R., Boulding, E., Farrell, A., Glebe, B., Elliott, J., Wolters, W.R., Schulte, P. 2013. Variation in temperature tolerance among families of Atlantic salmon (Salmo salar L.) is associated with hypoxia tolerance, ventricle size and myoglobin level. Experimental Biology. 216: 1183-1190. Interpretive Summary: Temperature tolerance and low oxygen tolerance of Atlantic salmon is highly variable at the family level. These traits appear to have a significant genetic component, which means that these individuals possess the raw material on which natural and artificial selection can act. As a result, Atlantic salmon may possess at least some capacity to adapt to environmental changes such as global warming. In addition, individuals or populations with a larger heart and specific higher myocardial protein levels might be selected under such conditions.
Technical Abstract: In fishes, performance failure at high temperature is thought to be due to a limitation on oxygen delivery (the theory of oxygen and capacity limited thermal tolerance, OCLTT), which suggests that thermal tolerance and hypoxia tolerance might be functionally associated. Here we examined variation in temperature and hypoxia tolerance among 41 families of Atlantic salmon (Salmo salar L.), which allowed us to evaluate the association between these two traits. Both temperature and hypoxia tolerance varied significantly among families and there was a significant positive correlation between critical maximum temperature (CTmax) and hypoxia tolerance, supporting the OCLTT concept. At the organ and cellular level, we also discovered support for the OCLTT concept since relative ventricle mass (RVM) and cardiac myoglobin (Mb) levels both correlated positively with CTmax (R2 = 0.21; P < 0.001 and R2 = 0.17; P = 0.003, respectively). A large RVM has previously been shown to be associated with high cardiac output, which might facilitate tissue oxygen supply during elevated oxygen demand at high temperatures, while Mb facilitates the oxygen transfer from the blood to tissues especially during hypoxia. The data presented here demonstrate for the first time that RVM and Mb were correlated with increased upper temperature tolerance in fish. High phenotypic variation between families and greater similarity among full- and half-siblings suggests that there is substantial standing genetic variation for thermal and hypoxia tolerance, which could respond to selection either in aquaculture or in response to anthropogenic stressors such as global climate change.