#16-A Ch. 12
What is relatedness, r, in Hamilton's model?
r is a measure of the genetic similarity between individuals
What did Darwin say about altruism?
"special difficulty, which at first appeared to me insuperable, and actually fatal to my whole theory."
Why is altruism a central paradox of Darwinism.
Altruism is a central paradox of Darwinism because an allele that results in behavior benefiting other individuals at the expense of the allele's bearer would seem destined for elimination by natural selection
According to Hamilton's rule, when is altruism more likely to spread?
Altruism is more likely to spread when the benefits to the recipient are great, the cost to the actor is low, and the participants are closely related
According to Freeman, what is a mutually beneficial interaction?
An interaction where both the actor and recipient enjoy increased reproductive success
Inclusive fitness consists of what two components?
Inclusive fitness consists of the sum of its direct and indirect fitness Direct fitness = results from reproduction an individual achieves on its own, without help from related individuals Indirect fitness = results from additional reproduction by relatives that is made possible by the individual's actions
How does indirect fitness benefit an individual?
Indirect fitness results from additional reproduction by relatives that is made possible by the individual's actions. By benefiting their relatives through indirect fitness, the individual in turn receives a long-range benefit of helping their race, instead of immediate offspring
What is kin selection?
Natural selection leading to the spread of alleles that increase the indirect component of fitness
How do evolutionists resolve the paradox of altruism?
Selection could favor traits that result in decreased direct fitness if they increase the survival and reproductive success of close relatives
Why did research on Belding's ground squirrels conclude that whistles are selfish, but trills are altruistic? Give specific data.
Sherman's data show that when squirrels spot an attacking hawk and whistle, the whistling squirrel is captured only 2% of the time while non-whistling squirrels are captured 28% of the time. When squirrels spot a stalking mammal and trill, however, the trilling squirrel is killed 8% of the time while non-trilling squirrels are killed just 4% of the time. The squirrel raising the alarm increases its own peril to the benefit of other squirrels nearby.
Explain how young, nonbreeding birds gain benefits for indirect fitness by helping their parents raise their siblings.
When maternal siblings in a nest are more closely related to each other, the investments older offspring make in helping their parents breed yield greater gains in indirect fitness.
What is a selfish interaction?
the actor benefits at the expense of the recipient
What is an altruistic interaction?
the actor makes a sacrifice on behalf of the recipient
What is a spiteful interaction?
the actor suffers a loss in order to impose a penalty on the recipient