Measuring mating preferences: The use of manly’s beta

Abstract

The use of Manly’s (1985) statistic β, in mate choice experiments is discussed. Beta is a measure of the homogamic mating preference of one sex (usually females) of a strain. Beta has several advantages over previously proposed measures of deviation from random mating: (a) its sampling distribution is known and hence it can be used in establishing confidence intervals and in hypothesis testing; (b) this distribution is continuous and unimodal, even when fairly small numbers of individuals are used; (c) beta is not aifected by changes in the numbers of individuals used (provided the preference remains constant); (d) it is not aifected by changes in the ratios of the two strains, and (e) it is not aifected by the proportions of females mated. Several properties of β and its estimate from an experiment, β, are derived and have been verified for a wide range of conditions using computer simulations. Their consequences for experiments attempting to quantify sexual isolation are discussed. Finally, statistics to measure the significance of β values are given. © The Genetical Society of Great Britain.