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Which sex cares? Sexual conflict Parent-offspring conflict Parental investment.

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Presentation on theme: "Which sex cares? Sexual conflict Parent-offspring conflict Parental investment."— Presentation transcript:

1 Which sex cares? Sexual conflict Parent-offspring conflict Parental investment

2 What is parental care? building of nests or burrows production of large, yolked eggs care of eggs inside or outside parent provisioning and defense of young care after independence

3 Parental investment Benefit Cost Fitness benefit or cost Days of care

4 e.g., trade-off between caring for self versus offspring Visits per nestling Nectar LowMediumHigh Parental investment = how much parental care reduces parents future fitness Palestine sunbird Markman, S., B. Pinshow, and J. Wright The manipulation of food resources reveals sex-specific trade-offs between parental self-feeding and offspring care. Proc. R. Soc. Lond. B (2002) 269, 1931–1938

5 Which sex cares?

6 Marsh Wren Mean Number of Offspring Females: Without male help 2.95 With male help3.53 Males: 1 female (helping) females (no help) females (no help)12.80 Leonard, M.L Polygyny in marsh wrens: asynchronous settlement as an alternative to the Polygyny Threshold Model. Am. Nat. 136: Sexual Conflict

7 Best strategy may differ for males versus females Valera F, Hoi H & Schleicher B (1997) Egg burial in penduline tits, Remit pendulinus: Its role in mate desertion and female polyandry. Behav Ecol 8: = ESS problem

8 Parent-offspring conflict Benefit (to parent) Cost Fitness benefit or cost Days of care Benefit (to self)

9 Parent-offspring conflict Comparative evidence from begging displays

10 Get-away pens Confined pens (farrowing crates) P-O Conflict in Pigs Pajor, E.A Parent-offspring conflict and its implications for maternal housing systems in domestic pigs. PhD thesis, McGill University.

11 Confined: piglets do better 1) nurse more 2) heavier 3) grow faster Get-away: mother does better 1) nurses less frequently 2) interval to oestrus shorter 3) lower weight loss


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