Problem 4 Flashcards Preview

Genetics & Evolution for Psychology > Problem 4 > Flashcards

Flashcards in Problem 4 Deck (44)
Loading 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



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 ?

1. A behavior will not evolve, if C is too large in absolute terms

2. 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



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


Indirect reciprocity

Refers to the idea that it might be advantageous to help individuals who we have seen helping others in the past, even if that help wasn't specifically directed to us



Providing punishment is a form of cooperation

--> can make cooperation stable even in the absence of direct reciprocity


Humans are notable for the extent of their cooperation. Why is that ?

1. They have direct reciprocal one-on-one relationships

ex.: friendships, marriages

2. Collective actions/Contribution to joint ventures

--> the costs are potentially very large, but are sustained by a combination of danger of ostracism or punishment

ex.: going to war


Ultimate explanations

Are concerned with why a behavior exists

--> respectively the fitness consequences of a trait or behavior and whether it is (or is not) selected


Proximate explanations

Are concerned with how a certain behavior works

--> respectively the mechanisms that underpin the trait or behavior


Tit for tat

Cooperate in the first round, and then do what the other just did to you



Is a strategy where one first always co-operates unless the other defects – then he only defects 


Stay-loose shift

Keeping the strategy if you win, but changing it when you loose



Strategy that is basically tit for that, but sometimes tries defecting



Is a strategy which starts of cooperating and then defects to see what the opponent does and to find out their strategy


Indirect fitness

Refer to the genes that contribute to the next generation by an individual indirectly via helping relatives

--> offsprings produced by relatives


Direct fitness

Refer to the genes that contribute to the next generation by an individual directly via reproduction

--> direct offsprings


Parochial altruism

Altruism within a group has co-evolved with hostile behaviour towards the other group, factors combined result in fitness benefit

--> reduces fitness