Animal Behaviour: Psychology 3750

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Animal BehaviourPsychology 3750

• Lecture 26 November 20, 2009

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Emlen three theories for cooperative breeding
chapter 8 - Kinship

• Inclusive fitness help relatives
• Skew Theory control of breeding/too good to
  leave
• Ecological constraints too difficult to disperse

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Helping/not harming Relatives

• More alarm initiated by female ground squirrels
  (Fig 8.3 8.4)
• Higher murder rate Lower murder rates with kin as
  victims (Table 8.1)
• Coefficient of relationship (r) shows the
  proportion of genes shared (Fig 8.6

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Why is parental care the most common form of
helping?

• R 0.5
• Young typically benefit more from care than other
  o.5 relatives

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Emlen (1995) predictions about family dynamics

• First two predictions why/when colonial
  breeding?
• 1. Families will break up if new territory
  becomes available (habitat too difficult to leave
  home)
• How to test? Provide extra territories (Fig 8.10)

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Effect of rainfall on dispersal in bee-eaters
(Emlen 1982)
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Prediction 2 higher family stability with good
resources (too good to leave)

• Acorn woodpeckers (Fig 811)
• Larger territory (more holes) ? longer survival
  (Fig 812)

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Higher RS with more helpers in Jackels and
bee-eaters
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Do helpers actually help?

• Problem with previous analysis?
• Correlation more stay because territory is good?

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Experimental removals

• What if more young just stay on really good
  territories?
• 2/3 experimental studies show that helpers do
  increase reproducitve success

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Results of experimental removals - number of young

• RS control RS Exper Reference
• Babblers 2.4 0.8 Brown
  (Fig 8.7)
• Scrub jays 1.6 0.6 Mumme
• Moorhens 2.2 2.5 Leonard

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Prediction 4 helping should be directed towards
the closest relatives

• Bee-eater helpers differentially provision
  closest kin ( Figure 815)
• Eusocial insects restricted breeding caste,
  overlapping generations

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Prediction 4 helping should be directed towards
the closest relatives

• Bee-eater helpers differentially provision
  closest kin ( Figure 815)
• Eusocial insects restricted breeding caste,
  overlapping generations