Evolutionary dynamics of structured populations with density-dependent limitation of juvenile survival

Abstract

The paper considers evolutionary dynamics of a structured population with density-dependent regulation of juvenile survival. Such a type of density limitation is not unusual for natural populations. It occurs as either competition for food resources or sibling aggression, and, moreover, cannibalism or infanticide. Birth rate is assumed to change during the process of microevolution. The stability loss of non-trivial fixed points was shown to realize according to both the Neimark–Sacker​ scenario and the Feigenbaum one. The stability loss scenario is shown to be determined by both the mature individuals’ contribution to limiting juvenile survival and birth rate level. The bifurcations, dynamic modes and a possibility of their shifting are studied for the model proposed. The model reveals bistability and multistability both the population number and gene frequencies dynamics. There are bifurcations leading to fluctuations of gene frequencies in the proposed model. Thus, both monomorphic equilibriums and oscillation modes of the population genetic composition are simultaneously possible in the system. With the same values of population parameters in the case of variations in its current stage and/or genetic composition, such multistability can lead not only to a change in the dynamic mode due to an evolutionary growth of individual fitness, but also to a change in the evolution direction. As a result, different mechanisms of fluctuation emergence can be realized in a population at the same values of demographic parameters.