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inclusive fitnessGesamtfitness (ger.)

  • (a measure of) genetic fitness determined by the relative capacity of a kinship group to reproduce successfully, and usu. calculated by adding the reproductive success of an individual to the reproductive successes of the individual's relatives, each multiplied by their degree of relatedness. (OED 2011)

    Here then we have discovered a quantity, inclusive fitness, which under the conditions of the model tends to maximize in much the same way that fitness tends to maximize in the simpler classical model. For an important class of genetic effects where the individual is supposed to dispense benefits to his neighbours, we have formally proved that the average inclusive fitness in the population will always increase. For cases where individuals may dispense harm to their neighbours we merely know, roughly speaking, that the change in gene frequency in each generation is aimed somewhere in the direction of a local maximum of average inclusive fitness, but may, for all the present analysis has told us, overshoot it in such away as to produce a lower value. As to the nature of inclusive fitness it may perhaps help to clarify the notion if we now give a slightly different verbal presentation. Inclusive fitness may be imagined as 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. It is stripped of all components which can be considered as due to the individual’s social environment, leaving the fitness which he would express if not exposed to any of the harms or benefits of that environment. This quantity is then augmented by certain fractions of the quantities of harm and benefit which the individual himself causes to the fitnesses of his neighbours. The fractions in question are simply the coefficients of relationship appropriate to the neighbours whom he affects: unity for clonal individuals, one-half for sibs, one-quarter for half-sibs, one-eighth for cousins, ... andfinally zero for all neighbours whose relationship can be considered negligibly small.

    Hamilton, W.H. (1964). The genetical evolution of social behaviour, I; II. J. theor. Biol. 7, 1-52: 8. 


    inclusive fitness The sum of an individual's fitness, quantified as the reproductive success of the individual and its relatives, with the relatives devalued in proportion to their genetic distance. 

    Lincoln, R.J., Boxshall, G.A. & Clark, P.F. (1982). A Dictionary of Ecology, Evolution and Systematics: 126.