Pre- Versus Post-Breeding Population Projection Models? A Simple Fix to a Common Parametrization Error.

Population Projection Matrices (PPM) are discrete mathematical formulations of population growth that are key tools in demographic population studies, enabling the prediction of growth for populations structured with age, size, or other life stages. However, several studies have identified errors stemming from misconceptions related to survival and reproduction parameters, as well as confusion between post-breeding and pre-breeding in the case of Leslie matrices. The present work aims to propose a simple and robust method called Matrices Alternated Products (MAP) for reliably constructing PPM directly from life tables and empirical data. The MAP approach provides a systematic framework for defining both survival and reproductive parameters and producing pre-breeding and post-breeding matrices. The method we propose allows reducing errors and improving the accuracy of demographic population models, and the code we provide will allow population ecologists and wildlife managers to apply this method to any case study in practice.