title: Generalist niche, specialist strategy: the diet of an Australian percichthyid.
abstract: Dietary analysis revealed that an impoundment population of Australian bass Macquaria novemaculeata holds a generalist niche, but one arising from persistent individual specialization and interindividual variation. This 'individual specialist' strategy appeared adaptive, but the strength of individual specialization was largely independent of variation in diet composition, except during blooms of Daphnia sp. Diet composition and dietary overlap showed only moderate ontogenetic variation, and niche breadth showed no relationship with ontogeny. Macquaria novemaculeata showed an asymmetric predator and prey size distribution, consistent with many aquatic predators, with positive relationships between fish size and average, maximum and minimum prey size. There was no asymmetry in the relative size-based niche breadths of individuals, however, which indicates that the niche is a fixed 'window' of relative prey sizes. The difference in the dietary niche and prey-size relationships of M. novemaculeata at the population and individual levels highlights the necessity of assessing the niche at both these levels.
authors.affiliation: Evolution and Ecology Research Centre, and School of Biological, Earth and Environmental Science, University of New South Wales, Sydney 2052, Australia. james.smith@unsw.edu.au
authors.forename: J A
authors.initials: JA
authors.lastname: Smith
authors.forename: L J
authors.initials: LJ
authors.lastname: Baumgartner
authors.forename: I M
authors.initials: IM
authors.lastname: Suthers
authors.forename: M D
authors.initials: MD
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001315:Australia; D049628:Body Size; D004032:Diet; D005766:Gastrointestinal Contents; D016018:Least-Squares Analysis; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior