  After an introduction to the general topic of models for a given locus of a
diploid population whose quadratic dynamics is determined by a fitness
landscape, we consider more specifically the models that can be treated using
genetic (or train) algebras. In this setup, any quadratic offspring interaction
can produce any type of offspring and after the use of specific changes of
basis, we study the evolution and possible stability of some examples. We also
consider some examples that cannot be treated using the framework of genetic
algebras. Among these are bistochastic matrices.
