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| Species with a large adult–offspring size ratio and a preferred predator–prey mass ratio undergo ontogenetic
trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout
life, resulting in different species-level interaction motifs depending on the maximum adult sizes and population
size distributions. We explore the assembly and potential for coexistence of small communities
where all species experience ontogenetic trophic niche shifts. The life-history of each species is described
by a physiologically structured model and species identity is characterised by the trait: size at maturation.
We show that a single species can exist in two different states: a ‘resource driven state’ and a ‘cannibalistic
state’ with a large scope for emergent Allee effects and bistable states. Two species can coexist in two
different configurations: in a ‘competitive coexistence’ state when the ratio between sizes at maturation
of the two species is less than a predator–prey mass ratio and the resource level is low to intermediate, or
in a ‘trophic ladder’ state if the ratio of sizes at maturation is larger than the predator–prey mass ratio at
all resource levels. While there is a large scope for coexistence of two species, the scope for coexistence
of three species is limited and we conclude that further trait differentiation is required for coexistence of
more species-rich size-structured communities. | |
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