Stage-structured populations

Stage-structured models classify individuals by biological stage rather than by chronological age. This is useful when development, size or reproductive status is more important than age itself.

Typical stages

Examples include seed, seedling and adult plant; egg, larva and adult insect; or immature and reproductive individuals.

Transitions between stages

Individuals may remain in the same stage, survive and progress to another stage, reproduce, or die. These possibilities are represented by stage-specific transition and reproduction rates or probabilities.

Age versus stage

Age structure is appropriate when biological behaviour is closely tied to age. Stage structure is preferable when individuals of the same age may occupy different biological states.