Fisher’s Reproductive Value

Definition

The expected contribution of genes made by an individual or class to generations in the distant future

Natural selection is driven by differences in individual reproductive success, but a simple count of the number of children that individuals produce is often insufficient to describe their Darwinian fitness. For example, in a well-mixed population with a female-biased sex ratio, a mother who produces only sons will tend to have more grandchildren than will a mother who instead produces an equal number of daughters. And simply counting the number of grandchildren may also be insufficient, as these too may differ in their quality in terms of how many children they will have. R. A. Fisher’s theory of reproductive value resolves this conundrum by defining the fitness of individuals – or whole classes of individuals – in terms of their expected contribution of genes to generations in the distant future. This concept has broad application within Darwinian evolution and is...