Competition in Populations Consisting of One Age Group

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Abstract
Based on the rather voluminous literature the following mathematical models and descriptions are given: (1) When larval cannibalism is not involved, the fraction surviving to the imaginal stage is often linearly related to the initial number of larvae. (2) In the case of larval cannibalism the logarithm of the surviving fraction is linearly related to the initial number of larvae. (3) In the case of differential mortality of two genotypes composing a population, the mathematical model is graphed as a straight line for the total surviving fraction, and two parabolas concave towards it for the surviving fraction of the two genotypes, the abcissa being the initial number of larvae. Also the ratio between the surviving number of one genotype and the surviving total forms a straight line against this abcissa. (4) In the case of competition between larvae, the number of eggs per female (and the female weight) is linearly related to the reciprocal of the initial number of larvae, and (5) in the case of competition between adults the fecundity is often linearly related to the reciprocal of the number of adults, but (6) in some grain and seed pests the equation is complicated by the intro-duction of a linear term for mutual interference. (7) In some rare cases the sex ratio is influenced by the density. It is linearly related to the density (a)in Tineola with chromosomal and random determination of the sex, (b) in a hymenopterous parasite with chromosomal, but non-random determination of the sex, (c) in Moina (Cladocera) with phenotypical determination of the sex.