Study Guide Lectures 17-23

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24 Aug 2010
Lecture 17:
Different mating system :
Monogamy t sexes pair for breeding season for life t very rare t one to one t seahorses, sexual selection
low t male and females have similar morphology
Polygyny t males mate multiple in a breeding season t elephant seals t low parental investment t
females are limiting resources t males mates multiple to maximize the fitness
Polyandry t females mate multiple in a breeding season t pipefish t male limit resource t females mate
multiple to max the fitness
Intersex conflicts t female resist mating while male tend to overcome and mate
Claspers t used to hang on females
Sex role reversal t female-female competition and male choice
Eg. Giant water bugs, pipefish (male has brood pouch, male reproductive success depends on the size of
the pouch), katydids (flexible sex roles in Katydids t low food level, female mate more than males, males
become choosy when food level is low t hard for them to produce sperms. High food level t male mate
more t less chosier), spotted sand piper, plover
Rock-paper-scissors game in nature:
Side-blotched lizards t yellow, blue and orange
If blue is high, orange will increase
If yellow is high, blue will increase
If orange is high, yellow will increase
Little is static in mating system!!!
Lecture 18:
Non-selfish behaviours t altruism and cooperation
Hypo to explain coorperative behaviour:
reciprocity altruism t the cost will be repaid in the future
kin selecion t help other closely related ones t the donor of a cooperative behaviour increase
his/her inclusive fitness by helping a relative to reproduce and leave more offspring.
Coorperative behaviours can evolve when: rb-c is greater than 0
B=benefit c=cost r=coefficient of relatedness
Group selecion t the cost of a individual is offset compare the benefit to the whole group
Kin selection model showed a perfect relationship between the degree of relatedness and
P}(}}]ÀUµP}µo]}v]Z}}ÀUoµ][s contradict the theory
of natural selection which states that fitness differ among individuals
Eusociality t individuals in this species forego production all together
Social behaviours refers to the interaction with and responses to other individuals of the same species
Altruistic t ZÀ]}µ]v}Z[}µ]ÀµÁZ]o][}Áv}µ]À
Cooperative t behaviour that if adopted by two or more individuals benefit all t }v[
necessary costly for individuals who participate.
Game theory tdeveloped in Cold War t some number of players t set of possible strategies t some pay-
off schedule for playing A against B for all A and B t eg. Card games, chess
Hawk-Dove game
Contest between two individuals over obtaining a resource (food)
Two strategies t hawk (fight affressively) or dove (resolve contest peacefully)
Suppose R >2C, always good to be a hawk t independent of the number of the hawk
Suppose R<2C, if hawk is common, good to be a dove, if dove is common, good to be hawk,
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dependent on the number of the players
Given multiple encounters perhaps it does not cost to be selfish t can be exaimed using
Best strategy t tit for tat t cooperate on the 1st encounter t copy ur opponents last move
Why is TFT good t start with cooperating t stop if partner stops t if partner cheat and once
changed can cooperate again
Predator inspection to testvexperiment on guppies
Goup selection: -- not yet fully proved
Selection on alarm calling:
Group has more non-callers do poorly, and group with more callers do well
Kin selection:
Benefit closed relatives while animals have the ability to identify their kins
C=cost of altruism to the actoe
B=benefit of altruism to the recipient
R=genetic coefficient of relatedness
bR>c greater altruism towards more related ones
ground squirrel t prove the theory
evoltion by NS:
differential reproductive success of genes
NS cannoe favour self sacrificial genes t but can favour individual t protect the allele in the group
Favoured genes always increase in frequency each generation.
Lecture 19:
Parent-offspring conflict ( when the interest of the offspring and the parents does not coincide) and
partent-parent conflict (when the interests of parents are not totally shared)
Parent-parent conflict t based on the sexes in the sizes of the gametes
1 parent -1 offspring:
Benefit t fitness of current offspring will increase
Cost t number of future offspring
Maximize the benefit-cost
Offspring maximize t B-1/2C because they are half related to their siblings, but totally related to
Parents maximize t 1/2B-1/2C because they are half related to offsrings and each offspring is half related
to each other
Parent-parent conflict:
Mammals t female cares, no male
Pipefish t male cares, no females
Bird t both
Cost and benefit of deserting t cost t reduce quality of each offspring, benefit-increased quantity of
offsprings through re-mating
Kentish plover experiment:
#1 t benefit of deserting t resoning t low re-mating rate t big benefit, high re-mating rate t small
benefit; result t high benefit for females, low benefit for males
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