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Clutch size evolution under sexual conflict enhances the stability of mating systems

  • Henrik Smith
  • Roger Härdling
Publishing year: 2000
Language: English
Pages: 2163-2170
Publication/Series: Royal Society of London. Proceedings B. Biological Sciences
Volume: 267
Issue: 1458
Document type: Journal article
Publisher: Royal Society

Abstract english

Models of optimal clutch size often implicitly assume a situation with uniparental care. However, the evolutionary conflict between males and females over the division of parental care will have a major influence on the evolution of clutch size. Since clutch size is a female trait, a male has little possibility of directly influencing it. However, the optimal clutch size from a female's perspective will depend on the amount of paternal care her mate is expected to provide. The sexual conflict over parental care well in its turn be affected by clutch size, since a larger clutch makes male care more valuable. Hence, there will be joint evolution of mating system and clutch size. In this paper, we demonstrate that this joint evolution will tend to stabilize the mating system. In a situation with conventional sex roles, this joint evolution might result in either increased clutch size and biparental care or reduced clutch size and uniparental female care. Under some circumstances the initial conditions might determine which will be the outcome. These results demonstrate that it may be difficult to deduce whether biparental care evolved because of few opportunities for breeding males increasing their fitness by attracting additional mates or because of the importance of their care for offspring fitness by studying prevailing mating systems using, for example, male removals or manipulation of males' opportunities for fielding additional mates. In general terms, we demonstrate that models of life-history evolution have to consider the social contest in which they evolve.


  • Ecology


  • ISSN: 1471-2954
Henrik Smith
E-mail: henrik [dot] smith [at] biol [dot] lu [dot] se



+46 46 222 93 79

+46 70 978 20 56




Centre for Environmental and Climate Research (CEC)

+46 46 222 93 79

+46 70 978 20 56


Sölvegatan 37, Lund


Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden