The analysis of a two age-class single species, discrete-time climax population model

A difference equation model of a single climax species with two age classes (juvenile and adult) is studied. In a single species climax population model with no age structure, high population densities lead to extinction. It is shown that age structure makes it possible for a density that has extinction as its ultimate life history to have persistence as its ultimate fate with juvenile-adult competition. This suggests that juvenile-adult competition is key to species diversity. Finally, the results of the analysis are applied to several population models which are or are not capable of generating chaotic dynamics such as a period doubling bifurcation route to chaos or chaotic attractors. The results of the analysis are also applied to population data of the purse-seine anchovy, Engraulis capensis, that is located off the West Cape coast of South Africa.