Red-eyed Vireo

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 behavior Selfish behavior

(kin selection) (selected for)________________________________________________________________Individual Loses True altruistic behavior Mutually 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 InsectsHymenoptera (“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__________________________________________________________________Breeders r * Number of Cases % Cases__________________________________________________________________Father x Mother 0.5 78 44.8Father x Stepmother 0.25 17 9.8Mother x Stepfather 0.25 16 9.2Son x Nonrelative 0.25 18 10.3Brother x Nonrelative 0.25 12 6.9Grandfather x Grandmother 0.25 5 2.9Half brother x Nonrelative 0.13 3 1.7Uncle x Nonrelative 0.13 2 1.1Grandmother x Nonrelative 0.13 1 0.6Grandson x Nonrelative 0.13 1 0.6Great grandfather x Nonrelative 0.13 1 0.6Nonrelative x Nonrelative 0.0 20 11.5Total 174 100.0__________________________________________________________________* 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

Evolution of Self Deceit

Subconscious mind

Polygraph playback experiments

Evolution of Self Deceit

Subconscious mind

Polygraph playback experiments

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 + forgiveness can 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