Stage-structured evolutionary demography: Linking life histories, population genetics, and ecological dynamics

Demographic processes and ecological interactions are central to understanding evolution, and vice versa. We present a novel framework that combines basic Mendelian genetics with
the powerful demographic approach of matrix population models. The demographic component of the model may be stage-classied or age-classied, linear or nonlinear, time-invariant
or time varying, deterministic or stochastic, and may include dependence on environmental resources or interactions among species. Genotypes may affect, in fully pleiotropic fashion,
any mixture of demographic traits (viability, fertility, development) at any points in the life cycle. The dynamics of the stagegenotype structure of the population are given by a
nonlinear population projection matrix. We show how to construct this matrix and use it to derive sucient conditions for a protected genetic polymorphism for the case of linear,
time-independent demography. These conditions demonstrate that genotype-specic population growth rates (lambda) do not determine the outcome of selection. Except in
restrictive special cases, heterozygote superiority in lambda is neither necessary nor sufficient for a genetic polymorphism. As a consequence, population growth rate does not always increase
and populations can be driven to extinction due to evolutionary suicide. We demonstrate the construction and analysis of the model using data on a color polymorphism in the common
buzzard, Buteo buteo. The model exhibits a stable genetic polymorphism and declining growth rate, consistent with eld data and previous models.