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26 Cards in this Set
- Front
- Back
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Define altruism. Also know: Cooperation/sharing/mutualism/reciprocity, selfishness, spite
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When actor's fitness is harmed, and recipient gains fitness
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Name/describe 4 examples of altruism:
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black backed jackals (take care of young), meerkats (sentry), scrub jay/woodpecker(young), lions (food sharing/communal suckling)
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Name 3 POSSIBLE explanations for altruism (not necessarily correct)
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Group selection
Reciprocal altruism Kin Selection (most likely) |
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Group Selection
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Natural selection which has group as unit of selection, so if a trait in individual benefits the group, it is favored (MOST LIKLEY NOT CORRECT)
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Name 4 levels of selection possible
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Species, Group, Individual (traditional), Selfish "gene" selection
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Problems with higher order selection
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Replication occurs on level of DNA - groups/species ar removed. Connection between fitness and what is passed on is weaker.
Generation time faster at lower levels |
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Why not gene level?
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Genes entirely dependent on organisms that carry them to make it to next generation. It's not all gene level selection, but genes are important.
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Problems with group selection and altruism
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Altruism for group benefit not stable - cheaters will usually do better. (Game theory and ESS)
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Game theory
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Model when benefits of behaviors depend on actions of others
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Define: ESS
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Strategy which if adopted by all members of a population, cannot be invaded by an alternative
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Prisoner's dilemma
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both quiet - 1 yr
Quiet/confess = 5 yrs Confess/quiet = 0 years both confess = 3yrs Like altruism, you gain by defecting (confessing) Always Defect is an ESS |
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Why is group selection not a good explanation?
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Theoretical arguments say it doesn't work (prisoner's dilemma)
Simlations show it doesn't work Observations find no good evidence, lots against. Cheaters would be favored by natural selection |
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Define: reciprocal altruism
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Helping another in expectation that favor is repaid later
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What are the conditions needed for evolution of reciprocal altruism (which are often not met)
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Benefit to recipient > cost to donor
Individuals will meet again Individuals can remember each other and punish cheaters (memory) |
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Define: kin selection
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Fitness in terms of genes rather than individuals. Whatever increases chances of your genes being passed on is favored - including copies in relatives. Shared genes thus favor altruism among KIN. NEPOTISM
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Inclusive fitness
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Direct + indirect fitness
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MEMORIZE "R" VALUE CHART
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Self 1
Full Sibling .5 Parent .5 Grandparent .25 Half Sibling .25 Aunt, Uncle .25 First cousin .125 |
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Hamilton's rule
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be altruistic if r*B>C
B = benefit, 0 being none, 1 being life-saving C = cost to actor from 0-1 2 brothers, 8 cousins |
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Special case of Hamilton's rule
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B/C > r(own offspring) / r(recipient's offspring)
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Example of Hamilton's rule
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Blue wrens - sons should stay, daughters shouldn't
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More altruism examples
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meerkat babysitters of own genes, lion share food from hunting, grooming is highly nepotistic
Kin selection is a good explanation |
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Indirect/direct factors on kin recognition
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Indirect: location, olfactory/auditory/visual cues, prolonged social contact (humans grow up together)
Direct: phenotypic matching immune system |
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How do paper wasps/belding ground squirrel recognize kin?
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SCENT
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Kin selection is very widespread. Where is it most extreme? Where else is it common
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Insects - hive/colony are closely related
Plants - poison to non-kin |
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Misconceptions about kin selection
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Kin selection is not different from natural selection
Does not require a great deal of intelligence Not all members of a species is altruistic Individuals do not dole out altruism necessarily exactly according to r |
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Reciprocity vs reciprocal altruism vs mutualism
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Mutualism: both benefit
Reciprocity: delay between recipient's benefit and actor's benefit Reciprocal altruism: same as reciprocity, but there is cost to actor |
