The Price equation can also be applied to population context dependent traits such as the evolution of sex ratios. Additionally, the Price equation is flexible enough to model second order traits such as the evolution of mutability. The Price equation also provides an extension to Founder effect which shows change in population traits in different settlements Dynamical sufficiency and the simple Price equation Sometimes the genetic model being used encodes enough information into the parameters used by the Price equation to allow the calculation of the parameters for all subsequent generations. This property is referred to as dynamical sufficiency. For simplicity, the following looks at dynamical sufficiency for the simple Price equation, but is also valid for the full Price equation. Referring to the definition in Equation (2), the simple Price equation for the character can be written: For the second generation: The simple Price equation for only gives us the value of for the first generation, but does not give us the value of and , which are needed to calculate for the second generation. The variables and can both be thought of as characteristics of the first generation, so the Price equation can be used to calculate them as well: The five 0-generation variables , , , , and must be known before proceeding to calculate the three first generation variables , , and , which are needed to calculate for the second generation. It can be seen that in general the Price equation cannot be used to propagate forward in time unless there is a way of calculating the higher moments and from the lower moments in a way that is independent of the generation. Dynamical sufficiency means that such equations can be found in the genetic model, allowing the Price equation to be used alone as a propagator of the dynamics of the model forward in time. Full Price equation The simple Price equation was based on the assumption that the characters do not change over one generation. If it is assumed that they do change, with being the value of the character in the child population, then the full Price equation must be used. A change in character can come about in a number of ways. The following two examples illustrate two such possibilities, each of which introduces new insight into the Price equation. Genotype fitness We focus on the idea of the fitness of