| Abstract: |
| Leslie matrix projection models have long served as powerful tools for tracking populations and their age structure over time. One of their main appeals is the simplicity that arises from grouping individuals into age classes in which all individuals have the same vital rates. Nevertheless, in natural populations many traits influence survival and reproduction and so real-world age groups are composed of a heterogeneous mix of individuals with different vital rates. This heterogeneity is sometimes accounted for in models by expanding the Leslie matrix to include multiple phenotypic classes within each age category; however, it becomes increasingly difficult to analyze these matrices as the dimension increases. Here, we present 3 theorems about when and how projection matrices for populations structured by both age and phenotypic classes can be collapsed to smaller and more easily evaluated matrices while preserving the general solution of the original model. |
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