The genetics of viability selection

That's a pretty exhaustive (and exhausting) list of the ways in which selection can happen. Although we're going to focus our study of natural selection just on viability selection, it's important to remember that any or all of the other forms of selection may be operating simultaneously on the genes or the traits that we're studying, and the direction of selection due to these other components may be the same or different. We're going to focus on viability selection for two reasons:

1. The most basic properties of natural selection acting on other components of the life history are similar to those of viability selection. A good understanding of viability selection provides a solid foundation for understanding other types of selection.⁴

2. The algebra associated with understanding viability selection is a lot simpler than the algebra associated with understanding the other types of selection, and the dynamics are simpler and easier to understand.⁵