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Parental correlates of offspring sex ratio in Eurasian Oystercatchers

Heg, D. and Dingemanse, N.J. and Lessells, C.M. and Mateman, A.C. (2000) Parental correlates of offspring sex ratio in Eurasian Oystercatchers. The Auk, 117, 980-986. ISSN 0004-8038.

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We investigated hatchling and fledgling sex ratios in Eurasian Oystercatchers (Haematopus ostralegus) using random amplified polymorphic DNA markers. The overall hatchling (53% males, n = 374 hatchlings from 177 broods) and fledgling (49% males, n = 51) sex ratio did not differ significantly from unity. Hatchling and fledgling sex ratios were not correlated with laying date, clutch size, brood size, egg-laying sequence, territory quality male age, or male breeding experience, but hatchling sex ratio was positively correlated with age and breeding experience of females (0.05 < P < 0.075, n = 71). Older females produced more sons irrespective of the position of the offspring in the egg-laying sequence. Fledging mass was not correlated with female age, so the Trivers and Willard (1973) hypothesis is unlikely to explain our results. Sons dispersed less than daughters, so the local resource competition hypothesis of Clark (1978) might apply. The adaptive significance of a male-biased sex ratio in clutches produced by older females is speculative because the costs and benefits of dispersing versus philopatric offspring to parents and offspring are largely unknown. [KEYWORDS: Local resource competition; haematopus-ostralegus; monogamous oystercatcher; reproductive success; territory quality; paternal age; birds; selection; population; helpers]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:10867
Deposited On:24 Nov 2011 01:00
Last Modified:15 Jan 2014 09:33

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