Animal Behaviour: Psychology 3750

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Animal BehaviourPsychology 3750

• Lecture 23 November 13, 2009

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Alternative Reproductive Strategies in Male
Atlantic Salmon (Fleming Reynolds, 2004)

• Note change from (a) at sea to
• (b) on spawning grounds

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Alternate strategies in male salmon hooknose
versus jack
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What determines monogamy/polygynous?

• 1. Can males monopolize?
• 2. Second female success?
• 3. How important is biparental care?

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1. Resource defense polygyny depends on resource
distribution
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2. Polygyny female reproductive perspective
Lark Buntings
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• Female lark bunting choices over successive days
  at
• Onset of breeding season (Pleszcynska Hansell
  1980

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Why do females mate with polygynous males?

• If resources (territories) vary in quality,
  females may do better as second females (e.g.,
  lark buntings)
• Polygyny threshold model

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PTM Kenyan Kipsigis (Borgerhoff-Mulder)

• Resettling Kenyans after European colonization
• Larger territories, more additional wives
• More wives, lower female reproductive success

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3. Importance of biparental care
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Warbler mating systems (Fig 710)

• Left can trace evolution of degree of paternal
  care
• Right Males invest more when food supply is low

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Parental Care

• What does parental care include?
• Direct
• Feeding, brooding, defence
• Indirect
• Territorial defence, feeding female?

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Two Models of Parental Care

• 1. Provisioning (ethologist)
• 2. Parental investment versus conflict
  (behavioral ecologist)

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Parent-young contact maintained by

• Contact maintained by
• Early parents (1)
• Middle both
• Late young, (weaning conflict) (2)

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Investment theory (Trivers)

• Weaning occurs when cost to parent(s) exceeds
  benefit to offspring measured by
• survival of current offspring
• Production of future offspring

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Extra-pair copulations (EPCs) males

• Advantages
• Increase RS?
• Disadvantages
• Decrease RS?

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Advantages of EPCs for females (note p246 males
go to females?)

• Solicit paternal care/reduce infanticide
• Choose good genes/Increase genetic diversity
• Involved in mate switch/mate choice
• Fertility insurance

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Should males rear extra-pair young? (a
disadvantage for females?)

• Traditional theory says not!
• Paternal certainty ---gt paternal care
• Less support than predicted Dunnocks fit
  prediction
• Alpha males feed gt Beta males

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Certainty of Paternity

• Why would non-sires provide care?
• Failure to recognize/ cost of error
• Also keep mate, territory, or sire next
  brood/litter

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EPC, paternal care paternal certainty an
interspecific relationship
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Extra-pair copulations seabirds e.g., Common
Murre

• Paradox extensive paternal care single murre
  cant raise chick
• Apparently forced by male
• Actually female controlled (Walsh, 2001)
• Only one extra-pair chick in established pairs

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EPF variation 40 of species 0-5 EPFs 30
species lt 25 EPFs
Seabirds (murres)
Passerines (RWB), IB, warblers
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Is there a relationship between amount of
paternal care and EPF rate?

• Murres vs Passerines (indigo buntings, RWB,
  warblers, dunnocks)
• Species differences in importance of paternal
  care
• But not at individual level costs are high?