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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
