Non-random mating in the two-spot ladybird (Adalia bipunctata): I. A reassessment of the evidence

There is contradictory evidence concerning non-random mating among melanic and non-melanic phenotypes of Adalia bipunctata. Although most studies have found a mating advantage in favour of melanic individuals, one found random mating. Furthermore, in some samples the melanic mating advantage was frequency-dependent though not in others. In one population males alone gained a frequency-dependent mating advantage, and it has been argued that this is a result of a female sexual preference. There is no direct evidence for mate choice from any other population. In any case, melanic individuals of both sexes often gain a mating advantage so if mate choice is relevant, then these populations must contain “choosy” males as well as “choosy” females. Some of these apparent contradictions are explained by insufficient sampling and/or unsatisfactory statistical analysis. Nevertheless, populations are clearly different from one another and this is important when considering the nature of the melanic mating advantage. © 1990, The Genetical Society of Great Britain.