Ontogenetic niche shift

Ontogenetic niche shift (abbreviated ONS)[1] is an ecological phenomenon where an organism (usually an animal) changes its diet or habitat during its ontogeny (development).

[3] The best known representatives of taxa that exhibit some kind of the ontogenetic niche shift are fish (e.g. migration of so-called diadromous fish between saltwater and freshwater for purpose of breeding[2]), insects (e.g. metamorphosis between different life stages; such as larva, pupa and imago[2]) and amphibians (e.g. metamorphosis from tadpole to adult frog[2]).

[5] In complex natural systems the ONS happens multiple times in lifetime of an individual (in some examples the ontogenetic niche shifting can occur continuously).

The ONS, which is responsible for causing a noticeable phenotypic variation among individuals of the same species, plays important role in structuring communities and influencing their inside dynamics.

[4] In some cases individuals undergoing the ONS, in which they change their habitat, become a (mobile) link between two different communities (for example via flow of energy, matter and nutrients).

Researchers noticed that many species exhibit the ontogenetic niche shifting at different times and in a lot of examples the ONS occurred as a response to various abiotic and biotic environmental factors.

[2] Understanding the ontogenetic niche shifting in different species and its impact on the whole community is important when studying a biodiversity and ecosystem functioning.

[15] The ONS similar to that among insects happens in amphibian taxa,[2] the best known being frogs, which start as an egg and then hatch into a larval stage called the tadpole.

Diadromous fish species drastically change their habitat, when they set out on a journey from sea (saltwater) to rivers (freshwater) and vice versa.

The study has shown that riverine systems were populated primarily with adults and subadults of both sexes, that used the area as a non-nesting habitat.

Researchers noticed that young birds progressively direct towards lower trophic positions when they are coming closer to sexual maturity.

It is thought such ontogenetic niche shift was mainly a consequence of herbivory, the depth of the litter layer and presence of other plants (especially adult trees and shrubs).