Behavioural Constraints to Home Range Allometries in Aquatic Organisms.

Home range is the spatial evolutionary arena where an individual can succeed or fail. Its size reflects the balance between individual energy requirements and acquisitions. Since various behavioural traits can affect individual energy demand, we investigated how these traits affect individual space-use behavior and resulting home range size of aquatic organisms. We compiled data for 172 freshwater and marine species, ranging from invertebrates to marine mammals, spanning 8 orders of magnitude in body size and 13 in home range size. Across all taxa, home range size scaled allometrically with body size (  = 0.78, exponent = 1.68 ± 0.07). Behavioural traits explained an additional 27.15% of the variance beyond that explained by body size alone. In particular, carnivorous and pelagic species exhibited significantly larger home ranges than herbivorous and benthic ones, whereas migration and sociality were not retained as significant predictors beyond body size, despite migration affecting the intercept of the scaling relationship. We show that while body size is a strong predictor of home range, behavioural categories significantly modulate the allometric relationship. Our findings provide new insights into the behavioural constraints shaping spatial ecology in aquatic environments. These results underscore the role of energy-demanding behaviours in shaping spatial ecology, with implications for individual density, the intensity of intra-specific interactions, and patterns of interspecific coexistence.