Biochemical determination of parental uncertainty in white-fronted bee-eaters

Summary

Maternity and paternity uncertainty represent important costs to breeders among white-fronted bee-eaters (Merops bullockoides) in Kenya. Analysis of enzyme polymorphisms reveals that between 9% and 12% of all offspring are genetically unrelated to one or both of their putative parents. These ‘bastards’ are the result of three different sources of parental uncertainty: Extrapair copulation, intraspecific egg parasitism, and quasi-parasitism (parasitism by a female who was fertilized by the male attending the parasitized nest). The first two represent costs to males, who rear offspring that are not genetically their own; the latter two produce the same costs for females. Genetic relatedness plays an important role in defining the social structure of M. bullockoides populations. In order to predict patterns of parental investment and the choice of recipients for helping behavior, one would like to know the relative frequency of maternity vs paternity uncertainty. The possible use of maximum likelihood techniques to separate the sources of non-kin is discussed. Unfortunately, the sample size of detected non-kin in the present study was not large enough to allow constructive use of the technique for bee-eaters. A comparison of estimates from biochemical and behavioral analyses indicates that both methods can produce misleading results. Behavioral data can be used to test underlying assumptions of biochemical analyses, and vice-versa. Used together, the two approaches reinforce one another and strengthen the reliability of conclusions drawn from either one alone.