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What is parental investment?
any effort that increases the offspring's survival (thus RS) in the expense of the parent's ability to invest in another offsprings
Why does monogamy happen? (state 2 hypothesis)
1. Biparental care important- due to harsh physical environment, high competition within the species...etc
2. Forced Monogamy/Failed Polygyny- males are forced into mongamy bc of lost mating opportunities
Failed Polygyny/ Forced Monogamy
- 1. uniform distribution of females (spatial)
- 2. synchronized nesting (temporal)
- 3. Aggressive behavior when boundary is invaded
What happens when biparental care isn't essential?
Extra pair paternity should be higher...
Factors that influence genetic monogamy
- 1. higher need for biparental care
- 2. genetic quality of mate (high)
Factors that influence genetic polygyny
- 1. greater food abundance
- 2. Close nesting density (close distance to other males)
- 3. Genetic variability (females will choose the best)
- 4. Genetic quality of the neighbor
Will Genetic polygamy or sex bias in mate choosiness still operate in species where biparental care is essential? (in other words, is sexual selection still important in monogamy)?
- Ex. Termites. Sexual selective preference were found. Females like males with wide heads (biting, defense). Males prefer females with big body and fat, indicator of reproductive quality.
In termites, what if Operational Sex Ratio is biased?
Usually the rarer sex becomes the choosier one.
- Unselfish regard for other's benefits and welfare at the expense of the altruist.
- *evolutionary paradox
Kin Selection, Direct fitness vs Indirect fitness
- WD Hamilton's hypothesis.
- Higher r (relatedness) leads to higher altruism .
- Direct fitness- more RS of individual
- INdirect- the RS of relative still increases the passing of the genes
Hamilton's rule that says altruism will spread if the inclusive fitness benefits are greater than the costs.
Hamilton's rule that works everytime
Rb* b - Rc (c) >0
Inclusive fitness and Hamilton's rule (math)
- If an altruist produces x offsprings and partner produces y offsprings, then indlusive fitness is x + ry.
- If a non-altruist produces z offsprings and its partner produces w offsprings, inc fit is z+ rw .
- Altruism spreads when x + ry >z + rw
Benefits and costs of the social living
- disease, easily noticed by predators, competition, time and energy to the dominant one, adultery, female egg destroyed by inteference
- better degree of protection against the predators
- improved foraging
- opportunity for males to extra pair mate
- opportunity to interfere with competitor's RS.
- Donor + (delayed)
- Recipient +
Components of Kin Recognition
- Production - development of recognition cues (environmental vs. genetic, acquired vs. endogenous)
- perception- development of template,
- Action - how does discrimnator act based on his/her assessment of the degree of familiarity between recognition template and recognition cues
Green Beard (recogntion)
production, perception, and action all encoded by the single gene or set of tightly linked genes. The recognition template is not learned.
Spatial Location (kin recognition)
Template where location is learned to compare....Does not work when relatives are from unfamiliar locations, and may benefit unrelated individuals who happened to be in that location
Association template (recognition)
highly specific where only the familiar individuals (during the early development when the template is being learned) are recognized. Might not work when there are other relatives that were born after the developmental stage (which is common in large community based species like honey bees)
Phenotype Matching (recognition)
Referent used (i.e. armpit smelling). Allows recognition of unfamiliar kin.
Eusocial paper wasp kin recognition mechanism
It is based on the nest site association- the nest's odor, not from nest mates themselves. the nests provide unique hydrocarbon in the cuticles (production component).
Optimal setting for acceptance threshold in Kin Recognition
- Based on:
- 1. benefits of accepting kins and rejecting non-kin.
- 2. fitness consequences of erroneously accepting non-kin and rejecting kin.
- 3/ relative frequency of interaction with kins and non kins.