Abstract. This paper investigates a discrete-time model of a structured, density-limited population. It is assumed that at the beginning of each reproductive season, the population consists of two groups: a juvenile (immature) class and an adult (reproductive) class. Population dynamics are governed by birth and death processes, as well as by density-dependent limitations affecting the survival of both juveniles and adults. Notably, this formulation, which combines two mechanisms of density-dependent regulation, has not been considered previously. The analysis reveals the existence of two fixed points: a trivial equilibrium corresponding to population extinction and a nontrivial one. Stability analysis with parameter portraits show that the expansion of the stability area of the nontrivial fixed point is associated with increased survival of the adult class, whereas increased juvenile survival leads to its contraction. It is also shown that increases in both the growth rate and the strength of density dependence can either suppress or induce population oscillations. The resulting dynamics modes and bifurcation scenarios are examined in detail. In addition, a comparative analysis with a model that accounts only for density-dependent juvenile survival is performed. The key difference lies in a substantial reduction of the stability region of the nontrivial equilibrium and the emergence of quasiperiodic oscillations at lower growth rates, which makes the proposed model more consistent with the dynamics of natural populations where oscillations may arise at lower birth rates.

 

Key words: population dynamics, dynamic modes, stability, bifurcations, density-dependent regulation of survival