parental care patterns why provide care? when should care be terminated? who should receive care?

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  • Parental CarePatternsWhy provide care?When should care be terminated?Who should receive care?

  • Insect parental care

  • Distribution of parental care in vertebratesTeleost fishes = 21% of families show PC61% have male parental careAmphibians = 71% show PC50:50 maternal:paternalBirds = 100% show PCUsually biparental, sometimes one sexMammals = 100% show PCUsually maternal, sometimes biparental

  • Why male parental care?Randalls jawfish

  • Alternative hypotheses for providing careConfidence of paternityExpect parent with highest certainty to be parentalOrder of gamete releaseFirst to deposit gametes can desertAssociationSex nearest to offspring when care is needed

  • Parental care in fishes and frogs

  • Parental care can cost females more than malesMouthbrooding results in weight loss due to reduction in feeding,and the cost of brood care is higher in females than males

  • Alternative hypotheses for providing care: evidenceConfidence of paternity (fish and herps)Internal fertilization - 86% maternal careExternal fertilization - 70% paternal careOrder of gamete releaseSimultaneous fertilization (most species) - 78% paternalOther species - male deposits first, but doesnt leaveAssociationTerritorial males have external fertilization

  • How much care to invest?Parental investment: any investment by the parent in an individual offspring that increases the offsprings chance of surviving at the cost of the parents ability to invest in other offspring (Trivers 1972)Costs of parental care includeReduced future survivalReduced mating opportunities

  • Parental investment changes

  • Parental care detracts from future survival in willow tits

  • Sex ratio influences male parental careA female-biased sex ratio increases the cost of brood care for malesbecause parental care detracts from mating

  • Parent-offspring conflict

  • Parent-offspring conflictAssume fixed total resource that can be used to feed offspringParents want to distribute resource equitably to all n offspringOffspring want more than 1/n but not all since they are related to siblingsDifference between parent and offspring optimum increases as relatedness decreases Wallaby conflict

  • Parent-offspring conflict: how much care to provideParent is equally relatedto all offspring, butoffspring are less relatedto sibs than themselves.Assuming full siblings,i.e. r = 1/2Level of parental investmentBenefit or cost to parentBCB - measured in +units of RS of current offspringC - measured in - units of RS of future offspring

  • Begging loudness increases as relatedness within nest decreasesBrown-headed cowbird

  • Parent-offspring conflict: time of weaning(Full-sibs)

  • Parental investment and maternal ageIf reproductive value declineswith maternal age, then olderfemales should be willing toexpend more on parental care

  • Who should receive care?Concorde fallacy: past investment should not determine future investment - only prospects for future successExpect parents to use honest indicators of offspring quality to allocate care

  • Chick color affects parental feeding in mixed broods of cootsControl broods were unaltered(orange) or had orange featherstrimmed (black)Experimental broods had1/2 orange, 1/2 black chicksChick color likely indicatesoffspring health

  • Parent intervention in siblicideMB = masked booby, BFB = blue-footed booby Masked boobies tolerate higher rates of siblicideA chick excludes B chick


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