Problem 4 Flashcards
Levels of selection debate
Refers to a debate concerning which level of biological organization, natural selection is best seen as acting at
e.g.: genes, individuals, populations
Wynne Edwards explanation for reproductive restraint in birds
According to him, birds hatch less eggs during a scarce period so that the whole population will survive
–> altruism has to be able to outcompete selfishness, for the theory to work
Why is Wynne-Edwards explanation wrong ?
Altruism will not outcompete selfishness as it will eventually go extinct
–> as altruists only lay one egg as opposed to selfish ones, they will be disadvantaged relative to their competitors within the group
Evolutionary stable strategy (ESS)
Refers to a behavioral policy that, once common in a population, cannot be outcompeted by any alternative behavioral policy
ex.: selfishness
Why are altruistic alleles disadvantaged as opposed to selfish alleles ? Why do they go extinct ?
Because the average fitness of the selfish allele is higher than that of the altruistic allele
–> this means it will eventually go into fixation
Kin selection (Hamilton)
Refers to natural selection in which an apparently disadvantageous characteristic increases in the population due to increased survival of individuals genetically related to those possessing the characteristic
–> central component is the coefficient of relatedness
ex.: altruistic traits
Hamiltons rule
States that kin selection causes specific genes to increase in frequency when the genetic relatedness of a recipient to an actor multiplied by the benefit to the recipient is greater than the reproductive cost to the actor
Formula for Hamiltons rule
C < 1/2 x b
c= reduction in the actors reproductive success/cost
b= increase in the recipients reproductive success/benefit
r=1/2 –> coefficient of relatedness
Inclusive fitness
Refers to an individual’s direct fitness + any other additional fitness of its relatives resulting from helping him, adjusted by the coefficient of relatedness
–> sum of direct + indirect fitness
Alloparenting
Investing in or providing parental care to any non-direct offspring
–> kin selection plays a strong role
What are the constraints on hamilton’s rule ?
- A behavior will not evolve, if C is too large in absolute terms
- R is not sufficient to predict which behaviors will evolve
–> b + c are variable depending on the future prospects of the recipient + actor
Why can behaviors that benefit relatives at the expense of the actor evolve according to Hamilton ?
Because of allelic relatedness between kin
True altruism
Develops if a cooperation behavior, negatively affects the actors lifetime reproductive success
–> evolves + is maintained through kin selection
ex.: parental care
Mutual-benefit behaviors
Develops if a cooperation behavior, positively affects the lifetime reproductive success of both the recipient + actor
–> can only be maintained if cheating strategies can be prevented from prospering
Cheating
Taking the benefits of joint ventures without paying the cost
By-product benefit
Occurs when the benefits to others arise simply as a side effect of the benefit to the actor
–> no cooperation, therefore no cheating
Direct reciprocity
Refers to the idea that we help individuals who have helped us in the past
–> possible mechanism for the evolution of mutual-benefit behavior
ex.: Prisoners dilemma