Issues with individual selection Flashcards
What is altruism?
Behaviour that increases survival and reproduction of other individuals at a cost to one’s own survival and reproduction
What are 4 theories into how altruism evolved?
- Kin Selection
- Mutualism
- Manipulation
- Reciprocal altruism
What is kin selection?
Relatives (or kin) also have copies of an individual’s genes
Gene proliferation can occur through care for relatives [when they reproduce]
Acts may be phenotypically altruistic but geno-typically selfish
What is a diploid species?
Species which have two sets of chromosomes—one set inherited from each parent.
What does a coefficient of relatedness describe?
Probability of any one gene being shared by two individuals
Name the coefficients of relatedness for each family relation
r = 1.0 for identical twins
r = 0.5 for siblings
r= 0.5 for parents and children
r = 0.25 for grandparents +grandchildren
r =0.125 for grandparents + great-grandchildren
What are direct fitness and indirect fitness?
Direct Fitness- Component from personal reproduction
2. Indirect Fitness- Component from reproduction of kin
What is inclusive fitness?
An individual’s total fitness (direct + indirect)
What does an individuals ‘fitness’ refer to?
The measure of genes contributed to the next generation
How do you work out the costs of an altruistic act using the concept of kin selection?
C = number of offspring [forgone] in next generation x r
Since these are your offspring, r = 0.5
Gives a value for C in ‘genetic units’
How do you work out the benefits of an altruistic act using the concept of kin selection?
B = number of kin’s offspring in next generation [as a result of altruism] x r
Value of r is variable [depends how genetically close helped kin are to you]
Gives a value for B in ‘genetic units’
Frequency of an altruistic gene within a population will increase if…..
(Nk x r) genetic units > (Ns x 0.5) genetic units
Nk = number of kin’s offspring resulting
Ns = number of own offspring forgone
Give an example of kin selection
Hoogland (1983) studied alarm calls elicited by a (stuffed) badger [natural predator] on praire dogs
Alarm calls were more frequent when kin were present
Offspring and non-descendent kin were just as effective
What is mutualism?
Cooperation may occur because each participant gains [net] survival/reproductive benefit
Give an example of mutualism
Pied wigtails
Strongly territorial but share its territory with satellite bird which reduces food availability but also decreases defence time
What is manipulation?
Donors may be ‘tricked’ into behaving altruistically
Give an example of manipulation?
Cuckoo
Parasitises host nest during host’s laying period [one egg per nest]
Takes egg from host nest and replaces it with one of own; young eject rest
What is reciprocal alturism?
When animals display altruistic behaviour to another individual under the assumption that the altruistic behaviour will be reciprocated in the future
Give an example of reciprocal altruism
Wilkinson (1984) Regurgitation of blood by vampire bats
What is Darwinian fitness?
Measure of genes contributed to the next generation
What is Hamilton’s rule?
Frequency of an altruistic gene will increase in a population if the fitness benefit to altruist is greater than the fitness cost
B > C
