Investment and relatedness: A cost/benefit analysis of breeding and helping in the pied kingfisher (Ceryle rudis)
- 1 November 1984
- journal article
- research article
- Published by Elsevier BV in Animal Behaviour
- Vol. 32 (4), 1163-1178
- https://doi.org/10.1016/s0003-3472(84)80233-x
Abstract
Helping at the nest in birds is often termed altruism. However, so far, no study has ever demonstrated high costs to a helper's own lifetime reproductive success (=direct fitness), nor its compensation through benefits from relatives other than its own offspring (=indirect fitness). In this paper on pied kingfishers (Ceryle rudis) the relationship between investment, relatedness and inclusive fitness (expressed in terms of genetic equivalents) is investigated for breeding males, and males that help either relatives (=primary helpers) or strangers (=secondary helpers). With respect to guarding nests against predators and feeding young, primary helpers invest as much as breeders, but secondary helpers contribute significantly less. These differences in status and investment (measured in energy expenditure) affect the birds' future to such an extent that primary helpers have a lower chance of surviving and mating than secondary helpers. However, their costs in direct fitness are compensated by pronounced benefits to indirect fitness, resulting from improved survival of siblings and parents. An attempt is made to calculate the inclusive fitness of birds following different strategies over a 2-year period. It is concluded that (a) breeding is superior to helping and helping superior to doing nothing and (b) that kin-selection must be invoked to explain why surplus males choose the more costly primary helper strategy instead of the cheaper secondary helper strategy. Alternative explanations, including group selection, parental manipulation and reciprocity, are discussed.This publication has 45 references indexed in Scilit:
- The Distribution of Altruism Among Kin: A Mathematical ModelThe American Naturalist, 1981
- The Evolution of CooperationScience, 1981
- On Wasting Parental InvestmentThe American Naturalist, 1977
- Parental investment: A prospective analysisAnimal Behaviour, 1977
- Parental investment, mate desertion and a fallacyNature, 1976
- Alternate Routes to Sociality in Jays—With a Theory for the Evolution of Altruism and Communal BreedingAmerican Zoologist, 1974
- The Evolution of Reciprocal AltruismThe Quarterly Review of Biology, 1971
- Theory of use of the turnover rates of body water for measuring energy and material balanceJournal of Theoretical Biology, 1966
- The genetical evolution of social behaviour. IJournal of Theoretical Biology, 1964
- A study of blood-relationship in the natural society of the Japanese macaquePrimates, 1963