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Published byCalvin McGee Modified over 9 years ago
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Recipient/Donor Effects Non-Kin and Relatives
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Kin Selection Question: Reproductive Altruism Eusocial Insects Reproductive, Worker Castes Cooperative Brood Care Multiple Origins Hymenoptera, Isoptera
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Kin Selection Fitness: Lifetime Reproductive Success Inclusive Fitness Direct & Indirect Components Ego (Actor) & Relative(s)
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Helpers at the Nest: Feed Siblings
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Inclusive Fitness
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Direct Fitness Component of Behavior: Net Benefits to Ego Kin Altruism: Net Benefit < 0, Hence Cost to Altruistic Ego
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Inclusive Fitness Indirect Fitness Component of Behavior: Net Changes to Relatives’ Fitness, Devalued by Coefficient of Relatedness r, Caused by Ego’s Behavior Does Not Include Fitness Relatives Enjoy Outside of Interaction with Ego
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Inclusive Fitness Hamilton’s Rule for Kin Altruism B Net Benefit of Act on Relatives’ Fitness C Fitness Cost to Ego Natural Selection Favors Act r B – C > 0
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Inclusive Fitness Social Insects: Equivalent Version Hamilton’s Rule Gene for Kin Altruism: Care for Relative’s Offspring Assume Worker Has Altruism Allele Favored by Natural Selection?
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Haplo-Diploidy
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Inclusive Fitness Gene for Kin Altruism: Care for Relative’s Offspring B: Rear Extra b Offspring of Relative; r 1 Ego’s Relatedness to Offspring C: Lose c of Ego’s Offspring; r 2 Ego’s Relatedness to Offspring
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Inclusive Fitness Kin Altruism: Care for Relative’s Offspring r 1 b – r 2 c > 0 b, c Units of females
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Inclusive Fitness Haplodiploid Eusociality Worker Caste: All Females Queen = Mother to Ego Egg/Larva = Sister to Ego “Worker’s Daughter” = Cost c
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Inclusive Fitness Haplodiploid Eusociality Ego’s (Worker’s) Relatedness to “Daughter” Ego’s (Worker’s) Relatedness to “Daughter” Females Diploid, Have Father & Mother r 2 = ½ Since Daughter Would Also Have Father Cost C = r 2 c Cost C = r 2 c = 1/2
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Inclusive Fitness Haplodiploid Eusociality Ego’s (Worker’s) Relatedness to Sister, Daughter Ego’s Mother & Father Ego’s (Worker’s) Relatedness to Sister, Daughter Ego’s Mother & Father r 1 : Altruism Gene, Identical by Descent, Through Father (Haploid) or Mother = Queen (Diploid)
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Inclusive Fitness Haplodiploid Eusociality r 1 = ½ [(1/2) 0 ] + ½ [(1/2) 1 ] = ¾ Father: No Meiosis; Mother: 1 Meiosis Ego More Closely Related to Sister than Her Own Daughter
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Inclusive Fitness Haplodiploid Eusociality Reproductive Altruism Favored: r 1 b – r 2 c > 0 Let c = 1 female (daughter); (3/4)b – (1/2) > 0 b > 2/3; Reproductive Altruism Favored Via Kin Selection
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Inclusive Fitness Haplodiploid Eusociality b > 2/3; Reproductive Altruism Favored Via Kin Selection If worker can raise 2 sisters instead of raising 3 daughters, benefit of altruism = cost of altruism
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Inclusive Fitness Haplodiploid Eusociality Drones: Males Queen = Mother to Son Egg/Larva = Brother to Ego “Worker’s Son” = Cost c
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Inclusive Fitness Haplodiploid Eusociality Assume Worker Has Altruistic Allele Ego/Worker: Has Father Drone: No Father r 1 = Pr[Allele From Mother]/2 = (1/2) (1/2) 1 = 1/4
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Inclusive Fitness Haplodiploid Eusociality Worker Less Closely Related to Brother Than To (Hypothetical) Son Brother Than To (Hypothetical) Son More Workers Than Drones Workers Raise Drones
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(Haplodiploid) Eusociality Kin Selection: Focus on Within-Nest Social Behavior Nests Differ in Productivity = Rate of Forming New Colonies Focus on Between-Nest Competition Family Level Group Selection?
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(Haplodiploid) Eusociality Does Queen Manipulate Sisters (Workers) to Raise Her Offspring? Mechanism vs Function Current Areas of Research
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Kin Selection Facultative Sociality Individuals “Decide” to Breed Alone or Help Relative Altruistically Carpenter Bee Xylocopa sulcatipes Nest: Hollow Plant Stems, Excavate Cavity in Wood
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Kin Selection Females Nest Singly or in Pairs Pair: Mother & Daughter, Dominant and Subordinate Mother: Reproductive Consumes Any Eggs of Daughter Most Foraging, Provision Brood
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Kin Selection Mother & Daughter, Dominant and Subordinate Daughter: Helper, No Reproduction Guards Nest/Brood Nest Lost, New Occupant Kills Brood
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Why Daughter Altruistic? Cost: Offspring as Solitary, 1.5 Benefit: Extra Offspring Produced by Mother-Daughter Pair Pair: 5.5 Offspring Extra Offspring = 5.5 – 1.5 = 4 Weigh Cost & Benefit by Relatedness
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Why Daughter Altruistic? Altruist’s Guarding Reduces Chance of Losing Brood Allows Dominant More Time to Forage & Provision Brood Facultative Sociality: Economic Basis in Kin Selection
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Kin Selection “Inclusive Fitness Thinking” Eusociality Evolution of Family Parent-Offspring Conflict
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