The polygynandrous mating system of the alpine accentor, Prunella collaris. II. Multiple paternity and parental effort

Hartley, I. R. and Davies, N. B. and Hatchwell, B. J. and Desrochers, A. and Nebel, D. and Burke, T. (1995) The polygynandrous mating system of the alpine accentor, Prunella collaris. II. Multiple paternity and parental effort. Animal Behaviour, 49 (3). pp. 789-803. ISSN 0003-3472

Abstract

Parentage was determined by DNA fingerprinting for 110 young from 38 broods. There was no intraspecific brood parasitism and no young were fathered by males from outside the polygynandrous group. Nineteen (50%) broods were fathered by one male (15 by alpha, four by beta), 17 by two males (14 alpha and beta, two alpha and gamma, one beta and gamma) and two by three males (alpha, beta and gamma). A male's paternity share of a brood increased with his share of the matings, measured as the proportion of time he gained exclusive access to the female. This relationship was the same for alpha and beta males, which suggests that their copulations were of equal potency. Alpha males gained a larger share of the paternity by guarding fertile females and their overall paternity within the group tended to increase with female nesting asynchrony, although not significantly so, and to decrease with more competing subordinate males. Males were more likely to help feed nestlings if they gained a greater share of the matings with the mother. There was no difference between alpha and beta males in the relationship between the probability of helping and mating share. Given a choice between two synchronous broods, males preferred to help where their mating share was greatest. When alpha and beta males helped at the same nest their share of the feeds reflected their share of matings, not their dominance rank. When only one male helped at a nest, alpha males decreased their amount of help with decreased mating share, whereas beta males did not. This difference may arise because alpha males have greater chances of mating with other females in the group, so opportunity costs of helping are greater for them. How these different helping responses influence female preference for alpha versus beta males is discussed.