The Genetical Evolution of Social Behaviour 1 on Superphysics

Inclusive Fitness

Tue, 27 Feb 2024 00:00:00 +0000

This describes a genetic mathematical model which allows for interactions between relatives on one another’s fitness.

The Model

Tue, 27 Feb 2024 00:00:00 +0000

The model is restricted to the case of an organism which reproduces once and for all at the end of a fixed period.

Survivorship and reproduction can both vary but it is only the consequent variations in their product, net reproduction, that are of concern here. All genotypic effects are conceived as increments and decrements to a basic unit of reproduction which, if possessed by all the individuals alike, would render the population both stationary and non-evolutionary.

Mon, 01 Jan 0001 00:00:00 +0000

An alternative approach, however, shows that the arrays (Sa,>, are sufficient to define the selective effects. Every effect on reproduction which is due to A can be thought of as made up of two parts: an effect on the reproduction of genes i.b.d. with genes in A, and an effect on the reproduction of unrelated genes. Since the coefficient I measures the expected fraction of genes i.b.d. in a relative, for any particular degree of relationship this breakdown may be written quantitatively: (~aredA = r(hel.L + Cl- r)(JaredA. The total of effects on reproduction which are due to A may be treated similarly : IX, WreJA = IX, @adA + z, Cl- r) @areA or F (h), = F r@& + C Cl- r>(WA, r which we rewrite briefly as 6T; = 6Rf4 + 6S,, where 6Rz is accordingly the total effect on genes i.b.d. in relatives of A, and SS, is the total effect on their other genes.

Mon, 01 Jan 0001 00:00:00 +0000

Inclusive fitness is the personal fitness which an individual actually expresses in its production of adult offspring as it becomes after it has been first stripped and then augmented in a certain way.