Intraspecific resource partitioning due to ontogenetic niche shifts occurs in many species. This is probably most obvious when age groups live in different habitats and use different types of food. Examples of such ontogenetic niche shifts include particle-feeding amphibian larvae that turn into carnivorous adult amphibians, immature stages ofaquatic insects that turn into adult terrestrial insects, and planktonic marine invertebrate larvae that settle down to be sessile adults. Other species live in the same general habitat but use distinct food types depending on size or age class, as for example fish, where the young are gape-limited planktivores or herbivores and the adults are predators. There might also be large onto-genetic changes in diet within the same general food type as for example for predators that start to feed on small prey species but as they grow they can and will include larger prey types in their diet.
Differences in diet over the ontogeny of an animal can have different reasons. Search and handling efficiencies can change as animals grow and gape-limitation eases. Other animals change their diet with growth because predation risk declines with size, allowing them to use previously risky habitats. Still other species exhibit a fundamental change in habitat use as a result of life-history changes or dispersal (e.g., marine invertebrates with planktonic larvae that settle to become sessile adults).
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