Chapter 8 Flashcards
Kinship
Relationship through common characteristics or common origin
Cooperation among relatives tend to be common leading to factor to social behavior
Kin selection
The process by which traits are favored because of their beneficial effects on the survival of relatives
Enhance reproductive success of relatives
Why is a trait favored?
Shared genes and behavior between kin can increase the future representation of ego’s genes
Altruism or selflessness
Some animals behave in ways that reduce their individual fitness but increase the fitness of others
Altruism
Personal sacrifice for the good of the group
Inclusive fitness
The total effect an individual has on proliferating its genes by producing offspring and helping close relatives produce offspring
Evolutionary definition of kinship
Probability that individuals share genes that they have inherited from common ancestor
Relatedness
The probability that two individuals share genes that are identical by descent
Sibling relatedness=0.5
Hamilton
Predicts when natural selection would favor altruistic acts among related individuals
(AΣ1rb)-c>0
(AΣ1rb)-c>0
B=the benefit that others receive from the trait/gene (safety when heard the call)
C=the cost accrued to the individual expressing the trait (danger of being killed)
R=probability of relatedness (closeness among group)
A=how many individuals affected by the trait
Three key variables in an altruistic act
Benefit to the recipient
Cost to the altruist
Coefficient of relatedness
High relatedness
rXb is greater than c as b> and c< the probability of rb is greater than c increases
As A increases natural selection for the trait is more favored
Brown’s offspring rule
Uses offspring as the currency of measure and provides a means to eliminate fitness and costs of assisting kin
Reciprocal Altruism
Altruistic behavior toward unrelated individuals can be adaptive if the aided individual returns the favor in the future
Steve Emlen’s theory of family
Kin selection- inclusive fitness
Ecological constraints theory- examines distribution of mature offspring
Reproductive skew theory- examines how reproduction is divided among potential breeders by predicting conditions that should favor conflict or cooperation over breeding decisions
Parent offspring conflict
A zone of conflict between how much a given offspring wants in terms of parental resources and how much a parent is willing to give
Weaning (Parent offspring conflict)
When mothers consider her life time reproduction success and reduce aid while each current brood also weigh its reproductive success (survival) more than the reproductive success of other sibling and beg for more aids
Sex ratio in social insects (parent offspring conflict)
Male insects are haploid, while females are diploid. Sisters are more related and three times related to workers
What happen if the queen dies and is replaced by one of her daughters?
Workers are equally related to the new queen’s sons and daughters and so they should favor a 1:1 sex ratio
Parent induced infanticide (abortion/miscarriage)
Occurs when mother residual reproductive value is high and a resource is scare
Factors: age of female and resource
Residual reproduction
When a female has more reproductive opportunities in her future
Rule of thumb models
In species where kin groups are segregated from one another over relatively long periods of time, a second form of kin recognition may evolve
