BIOL3046 Lecture Notes - Lecture 5: Kin Selection, Evolutionarily Stable Strategy, Selfishness
5 Jul 2018
School
Department
Course
Professor
Animal Behaviour BIOL3046 460381099
Lecture 5: Kin selection and evolution of social behaviour.
Cooperation: Both parties benefit. Example: Foraging in social insects allow the sharing of
information.
Selfishness: Actor benefits, receiver is harmed.
Altruism: Receiver benefits, actor suffers costs. Example: Sterility in social insects as
workers do not breed, but still help the queen.
Spite: Both parties pay a cost, relatives benefit. Example: Worker bees lay eggs,
others eat the eggs, punishing behaviour that is bad for the group.
Altruism In regards to forgoing personal reproduction, to help others reproduce.
• Impossible to explain in Darwinian terms, as any genes that contribute to altruism
should not be passed on. Thus other hypothesis for the presence of altruism are needed.
• Group selection hypothesis: It evolves for the good of the species, however it is not
evolutionarily stable as there will always be some selfish genes so you will always have a
balance between altruistic and selfish genes. Example: Populations regulate their size
because it prevents extinction of the group, thus outcompeting unregulated groups;
Reproduction when resources are limited.
• Kin selection hypothesis: Help sibling (of close kin) reproduce, still benefits you as your
genes are in the offspring. When the costs high, more likely to show altruism to highly
related individuals. Example: Haplo-diploid insects. Workers are ¾ related to their
sisters, which means they are more related to their sisters than offspring. Thus, it is
better to not personally reproduce but rather help mother reproduce.
Calculating relatedness (r)
• Probability of two alleles being related by decent. Calculated by
where n is the
number of steps from the individual through all common ancestors, back to the other
individual being considered.
Hamilton’s rule
• An allele promoting altruism can spread whenever
.
• Individual advantage if
Document Summary
Lecture 5: kin selection and evolution of social behaviour. Example: foraging in social insects allow the sharing of information. Example: sterility in social insects as workers do not breed, but still help the queen. Example: worker bees lay eggs, others eat the eggs, punishing behaviour that is bad for the group. In regards to forgoing personal reproduction, to help others reproduce. Impossible to explain in darwinian terms, as any genes that contribute to altruism should not be passed on. Example: populations regulate their size because it prevents extinction of the group, thus outcompeting unregulated groups; Reproduction when resources are limited: kin selection hypothesis: help sibling (of close kin) reproduce, still benefits you as your genes are in the offspring. When the costs high, more likely to show altruism to highly related individuals. Workers are related to their sisters, which means they are more related to their sisters than offspring.
