A unifying approach to discrete single-species populations models

Abstract

In this article, we write the recruitment function \begin{document}$f$\end{document} for the discrete-time density-dependent population model \begin{document}$p_{n+1} =f(p_n)$ \end{document} as \begin{document}$f(p) =p+r(p)p$\end{document} where \begin{document}$r$\end{document} is the per capita growth rate. Making reasonable assumptions about the intraspecies relationships for the population, we develop four conditions that the function \begin{document}$r$\end{document} should satisfy. We then analyze the implications of these conditions for the recruitment function \begin{document}$f$\end{document} . In particular, we compare our conditions to those of Cull [2007], finding that the Cull model, with two additional conditions, is equivalent to our model. Studying the per capita growth rate when satisfying our four conditions gives insight into contest and scramble competition. In particular, depending on the properties of \begin{document}$r$\end{document} and \begin{document}$f$\end{document} , we have two different types of contest and scramble competitions, depending on the size of the population. We finally extend our approach to develop new models for discontinuous recruitment functions and for populations exhibiting Allee effects.