number of common ancestors (or pathways) x 0.5^ number of generational links

e.g., Grandparent to grandchild: 1 ancestor, 2 generational links --> 1(0.5)^2=0.25=r

First cousins: 2 common ancestors (grandparents), 4 generational links (one from child to parent, two from parent to aunt, one from aunt to cousin)--> 2(0.5)^4=0.125=r

Based on the premis that individuals reproduce with unconscious goal of propagating alleles more successfully than other individuals

Altruism toward kin is advantageous when r_bB>r_cC

or: B (the additional offspring that the recipient gains from being helped) x r (r of donor to those offspring) 

>

C (number of offspring lost/unborn by donor) x r(0.5)

e.g. help sister produce 3 extra offspring instead of 1 of your own:

3 x 0.25 > 1 x 0.5 --> yes

1) Directly, through production of own offspring

2) Indirectly, through positive effects on reproductive success of their relatives

Primaries help mom and younger sibs

Secondaries help unrelated nesting pairs

Primaries demonstrate altruism can be adaptive (deliver almost as much food to young as does father)

Secondaries show helping need not be altruistic but may generate direct fitness benefits to helpers  (don't deliver much food, so gains in first season are minimal compared to primaries, but in second season, benefit from increased chance of finding a mate and increased chance of survival to second season, so benefits outweigh those of primaries in second season)

1) Preferences that develop as a result of association during ontogeny

2) "Mediated recognition" through a third individual

3) Phenotypic matching --> depends on strong correlation between phenotypic similarity and genotypic similarity

Chick have more individually distinctive calls

Adults learn their chicks' calls faster and more accurately

Genetic mechanisms for kin recognition?

Learned mechanisms for kin recognition?

Phenotypic matching

Location (in nest/territory), Olfactory, auditory, or visual cues, prolonged social contact

Tendencies of Belding's ground squirrels to call in response to predators?

What does this suggest?

Females w/ offspring or w/ only nondescendant kin as neighbors are more likely to call in response to predator than are females w/o relatives in neighborhood

This suggests both direct and indirect selection contribute to maintenance of alarm calling behavior in this species (supports parental care and altruism hypotheses respectively)

Major Histocompatibility complex: large genomic region that plays a major role in immune system, autoimmunity

Highly polymorphic (variable)

Proteins encoded by MHC expressed on surface of cell and display self and non-self antigens

MHC plays a role in mate selection, kin recognition via olfaction

Research on congenic mice suggests that individuals with same MHC treat each other as kin

Similar egg appearance and begging behavior in female and baby widowbirds to finches that they parasitize

Larger birds nesting as parasites at feeding advantage because parents tend to feed larger offspring better

Inability to distinguish own eggs or babies from parasites (similar looking widowbird eggs, similar sounding cuckoo calls)

Cost of abandoning nest, eggs already laid (If abandon own eggs by mistake or treat as froeign eggs, it is costly

Extortion by parasite

If the similar sounding horsfield's bronze-cuckoo:

1) Lays egg before fairy wren clutch...?

2) Laid after wrens have begun to incubate a complete clutch...?

3) Laid in the midst of partial clutch...?

1) host will build new nest over parasitized egg

2) host will abandon nest

3) Will often incubate all eggs

Even though warblers are severely harmed by having baby cowbirds in nests, females w/0 several nest holes in territory often tolerate cowbird for lack of suitable alternative nest site

Tend to accept parasitized eggs near end of breeding season for fear of cost of difficulty to rear new breed

Parasitic cuckoo mother would come back and kill magpie eggs if mother magpie ejects cuckoo egg

Reproductive success in terms of # of fledgelings is often higher in those that accept parasitic egg

Best option is to remove egg and block off nest (experiment) so cowbirds cannot prey on nestlings

Cooperation

Inbreeding avoidance 

Types of "kin" recognition:

Which are not favored by kin selection?

1) kin vs. non-kin

2) within kin class, different degrees of r

3) other individuals' kin (or close associates)

4) abstract kin classes (e.g. "uncle", "sister")

(3 and 4 not favored by kin selection)