The Optimal Balance between Size and Number of Offspring Christopher C. Smith, Stephen D. Fretwell, American Naturalist, Vol. 108, No. 962 (Jul. - Aug., 1974) , pp. 499-506
The relationship between the energy expended per offspring, fitness of offspring, and parental fitness is presented in a two-dimensional graphical model. The validity of the model in determining an optimal parental strategy is demonstrated analytically. The model applies under various conditions of parental care and sibling care for the offspring but is most useful for species that produce numerous small offspring which are given no parental care.
Lack D. 1947. The significance of clutch size. Ibis 89: 302-352