Intrasexual vs. intersexual (epigamic) sexual selection Mating preferences in Drosophila and pigeons Certainty of Maternity, Uncertainty of Paternity “Battle of the sexes” Cuckoldry —> jealousy Desertion —> Mating Rituals, Complex Courtship Sex that invests most in most choosy about mates Natural selection produces a correlation between male genetic quality and female preference “Sexy son” phenomenon (females cannot afford to mate with males that are not attractive to other females) Mating systems, monogamy, polygamy, polygyny threshold Marsh nesting (wrens, blackbirds, jacanas) Pinniped harems and sexual size dimorphisms Floating populations of non-breeding males Handout 5

Red-eyed Vireo Ecological sexual dimorphisms

A. J. Marshall

Four Possible Situations Involving an Individual ’ s Behavior and Its Influence on a Neighbor ________________________________________________________________ Neighbor(s) Gain Neighbor(s) Lose ________________________________________________________________ Individual Gains Pseudo-altruistic behaviorSelfish behavior (kin selection) (selected for) ________________________________________________________________ Individual Loses True altruistic behaviorMutually disadvanta- (counterselected) geous behavior (counterselected) _________________________________________________________________

W. D. Hamilton (1964) Kin Selection Inclusive Fitness Hamilton’s rule: r n b – c > 0 r = coefficient of relatedness n = number of relatives that benefit b = benefit received by each recipient c = cost suffered by donor r n b > c “ Adaptive Geometry of a Selfish Herd ”

“ Adaptive Geometry of a Selfish Herd ”

Eusocial Insects Hymenoptera (“thin wings”) Ants, bees, wasps, hornets Workers are all females Haplodiploidly Isoptera (“same wings”) Termites (castes consist of both sexes) Endosymbionts Parental manipulation Cyclic inbreeding

Kin selection, inclusive fitness Hamilton’s rule: r n b > c (coefficient of relatedness) Pseudo-altruistic behavior Eusocial Insects Hymenoptera (“thin wings”) Ants, bees, wasps, hornets—all workers are females Haplodiploidly Isoptera (“same wings”) Termites (castes consist of both sexes) Endosymbionts Parental manipulation Cyclic inbreeding “Adaptive Geometry of a Selfish Herd”

White-Fronted Bee Eater, Kenya

White-Fronted Bee Eater Colony Female tossing out an egg

Helpers at the Nest in White-Fronted Bee Eaters in Kenya __________________________________________________________________ Breedersr * Number of Cases% Cases __________________________________________________________________ Father x Mother Father x Stepmother Mother x Stepfather Son x Nonrelative Brother x Nonrelative Grandfather x Grandmother Half brother x Nonrelative Uncle x Nonrelative Grandmother x Nonrelative Grandson x Nonrelative Great grandfather x Nonrelative Nonrelative x Nonrelative Total __________________________________________________________________ * r = coefficient of relatedness.

Reciprocal Altruism (Trivers 1971) Donor ––> Recipient Small costs, large gains, reciprocated Sentinels Robert Trivers Biological basis for our sense of justice? Friendship, gratitude, sympathy, loyalty, betrayal, guilt, dislike, revenge, trust, suspicion, dishonesty, hypocrisy

Game Theoretic Approaches Costs versus benefits of behaviors “ tit for tat ” strategy can lead to cooperation ( “ the future casts a long shadow back on the present ” ) Evolutionarily stable strategies = ESS (a tactic that when present in a population, cannot be beaten) Tit for Tat with Forgiveness John Maynard Smith

Evolution of Self Deceit Subconscious mind Polygraph playback experiments

Helpers at the Nest in White-Fronted Bee Eaters in Kenya Reciprocal Altruism (Trivers) Donor ––> Recipient Small costs, large gains, reciprocated Sentinels, selfish callers Biological basis for our sense of justice? Friendship, gratitude, sympathy, loyalty, betrayal, guilt, dislike, revenge, trust, suspicion, dishonesty, hypocrisy Game Theoretic Approaches Costs versus benefits of behaviors “tit for tat” strategy + forgivenesscan lead to cooperation (“the future casts a long shadow back on the present”) Evolutionarily stable strategies = ESS Evolution of self deceit makes for better liars Subconscious mind Polygraph playback experiments