**Midterm covers material from Feb.3 -Mar.5 th
Kin Selection occurs when natural selection favors the spread of alleles that increase the
- Possible individual interactions
Donor Recipient Evolution
Co-operation/mutualism + + Yes
Selfishness + - Yes
Spite - - No
Altruism - + ?
- Altruism evolution? Depending on the individuals involved, depending on the cost and
the benefit. It could evolve, it could not.
- How can altruism exist if the individual carrying the altruistic allele has reduced fitness?
o Because there could be increased inclusive fitness
Inclusive fitness includes both direct and indirect fitness
- What is selfless act by donor increases fitness of its kin?
- Hamilton’s rule allele for altruistic behavior will spread if:
o r > C/B where r=relatedness, C=cost, B=benefits. If r is less than the C/B ratio
then it won’t spread
o Coefficient of relatedness (r) = probability that homologous alleles in two
individuals are identical by descent (similar to inbreeding coefficient)
- Alarm calling
o 2 different types:
Trill attack of land animal
Whistle attack of air animal (hawk) o Those that call will have a higher chance of being attacked
o Expected amount of time they spend above the ground
o Why do females call more than males?
Females within the colony are also related to each other
They have a larger number of family members in the colony
The males move between colonies to mate
2% killed with whistle
28% killed without whistle
8% killed with trill
4% killed without trill
- They do adjust the alarm calls based on how related the individuals are
- Offspring help raise next generation
o In animals it occurs when resources limited
- Colonial 40-450 individuals/colony with subgroups in colony
o Non-breeders pair with members of the group
o All non-breeders help raise young in subgroup
o Who do the helpers help?
- Helpers help raise the offspring even if the offspring aren’t there’s. Helpers will help even
when there are limited resources.
- Natal those born in that same subgroup
- In-law born in another group and moved in
o More likely to help when born in the same subgroup
o More likely to help a relative
o Over 50% of offspring die before they fledge
o The more helpers, the more offspring that can be fledged
Need to be able to recognize kin, but how? - Phenotype matching imprint on parent’s traits
- “recognition” genes: ex. Major histocompatibility complex (MHC) produce odor c