Stability of physiological and behavioural determinants of performance in Arctic char (Salvelinus alpinus)

The physiological and behavioural mechanisms that confer behavioural domina nce are poorly understood. Although recent studies have shown a link betwee n metabolism and dominance, these studies relied on single measurements of both, and assumed that inter-individual variation of physiology and behavio ur were repeatable over time. This paper demonstrates that standard metabol ic rate is a repeatable trait in Arctic char (Salvelinus alpinus L.) and th at relative differences between individuals are consistent across a range o f environmental conditions. Furthermore, there were positive associations b etween metabolic rate, aggression, and competitive ability that were also r epeatable over time. However, there was no relationship between competitive ability (measured as feeding attempts) and subsequent growth. This may be due to an energetic cost of dominance: high rates of food capture were only attainable through high rates of effort. This, in addition to elevated agg ression, was thought to exert an energetic cost that could not be fully off set by the increased food intake.