Maternal effects and fitness consequences of individual variation in bottlenose dolphins' ecological niche.

The niche describes the ecological and social environment that an organism lives in, as well as the behavioural tactics used to interact with its environment. A species niche is key to both ecological and evolutionary processes, including speciation, and has therefore been a central focus in ecology. Recent evidence, however, points to considerable individual variation in a species' or population's niche use, although how this variation evolves or is maintained remains unclear. We used a large longitudinal dataset to investigate the drivers and maintenance of individual variation in bottlenose dolphins' Tursiops aduncus niche. Specifically, we (a) characterised the extent of individual differences in habitat use, (b) identified whether there were maternal effects associated with this variation and (c) investigated the relationship between habitat use and calving success, a component of reproductive fitness. By examining patterns of habitat use, we provide evidence that individual dolphins vary consistently between one another in their niche. We further show that such individual variation is driven by a strong maternal effect. Finally, habitat use and calving success were not related, suggesting that use of different habitats results in similar fitness outcomes. Niche partitioning, maintained by maternal effects, likely facilitates the coexistence of multiple ecotypes within this population.