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Inclusive Fitness. Psychology 3107. Introduction. Darwin was troubled by the preponderance of behaviour that seemed to be of no benefit to the actor Examples Sterile insect castes Bee stings Alarm calling Reproductive restraint. Reproductive restraint.
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Inclusive Fitness Psychology 3107
Introduction • Darwin was troubled by the preponderance of behaviour that seemed to be of no benefit to the actor • Examples • Sterile insect castes • Bee stings • Alarm calling • Reproductive restraint
Reproductive restraint • Birds can produce many more eggs than they actually do! • Wynne-Edwards beleied that selection also acted on the species level to stop massive overpopulation
Reproductive Restraint? • Lack argued that animals are doing what is best for the INDIVIDUAL • Big clutch means possible exhaustion, death • LIFETIME fitness, not just this season
Lack • Well, if clutch size depends on the environment, then clutch size should vary with quality of resources
Hamilton figured it out • Hamilton’s Response was theoretical • Look at behaviour from the gene’s point of view • Inclusive fitness = direct fitness + effect on fitness of others
Hamilton • C < rb • Or r > c / b • Remember, r is relatedness, c is cost b is benefit • Would you give your life for a brother? • No, but maybe 2 brothers, or 8 cousins • Two uncles and one mother….
Mechanism • For this to work there must be some sort of proximate mechanism • Easy for mother/father and child • How about everyone else? • ‘Green Beard’ hypothesis • Allele produces some phenotype • Also allows for recognition • Tough for a single gene….
The elusive mechanism • Proximity • Families • Little dispersal • So if close by, you are related • Example: • Leaf eating ants • Far nests more hostile • Different plants more hostile
More on mechanism • Those crazy ants • Split colony and put on different plants • Hostile, but non injurious! • Gene environment interaction baby! • Vervet monkeys • 2 year olds scream • Mother comes • Others watch the mother!
Mechanisms, pheremones and bees • Greenberg looked at bee relatedness and allowing bees in or not • Probably genetically determined odour
Conclusions • Group selection is silly • Individual selection is cool • Gene level selection is VERY cool • Hamilton is a genius • Don’t over use this • Gives us some insight into some nasty human behaviour