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Game theory & ESS (Alternative reproductive strategies (Conditional…

- - - - Sex Ratio - Producing exclusively male offspring may provide benefits if the rest of the population are female. But this would be counterproductive if the rest of the population are also males. = FREQUENCY DEPENDENT.
        If a tactic or strategy is thus immune to invasion of another strategy so long as most individuals of that population follow it is called an Evolutionarily Stable Strategy.
      - Foraging strategies (Patches) - if we want to predict the point when it is worth an animal leaving a certain patch to forage elsewhere.
        Currency assumption = goal is to optimise long-term average rate of energy intake.
        Constraint assumptions = Expected energy gain within the patches.
        Biological assumptions = assume the animal has complete information. only cost is travel time towards a patch, so doesnt pick up further costs or use additional info as it travels.
      - Group huntings - African lions (Panthera leo) - female lions hunt in groups - although paradoxically, little evidence for hunting in large groups enhances food return to individuals. So, Housten et al 1988 and clark 1987 used a dynamic model where the state of animal depends on hunger or kg of food in stomach.
        
        The optimum group size depends on the animals current state as well as the prey type and habitat. if prey is large and lion has a ful belly, larger groups provide higher 30 day survival probabilities than small groups due to the low kill probabilities and inability of small groups to use all meat on a zebra eg before it rots. .
        Hungrier lions should hunt in smaller groups. When prey is scarce, prides may break up
        
        One advantage of group living is joint defence of infanticide by males. another is maintenance of a territory appears to be vital for reproductive success - a single lion foraging on another territor is more likely to get killed.
      - Hawk-dove game - Winner of any contest haoms benefit. Loser suffers a cost. When doves meet, they share the benefit.
        So costs < Benefits
- - - - Decade long fitness studies and game theory demonstrated that 2 throat colour morphs (lizards maybe?) were refined by selection in which the strength of natural selection varied with density.
        
        R strategies produced many eggs, and favoured at low densities.
        K strategies produced large eggs and were favoured at high densities.
        progeny size should also be under negative frequency-dependent selection in that large progeny will have a survival advantage when rare, but the advantage disappears when they become common.
        
        Intrinsic causes of frequency and density dependent selection promotes an evolutionary game with 2-generation oscillation. every other generation, the cycle alternatively favours large progeny (crash year) or large clutches of small progeny (boom years). so progeny size under negative frequency-dependent selection. (large hatchlings are selected for when rare).
        
        The alternative throat-colour morph in side-blotched lizards therefore may have arisen as a mutation in an endocrine gene, given the effect of hromones on the expression of orange vs yellow throat. So the locus had pleiotropic effecrs on physiology and behaviour.
        
        UNLIKELY that all variation in clutch size and egg mass of morphs is due to pleiotropic effect of a single throat-colour locus. Many loci undoubtedly affect clutch size and egg mass.
  - - - Evidence does suggest that alternative tactics may be regulated by relatively minor hormone differences. so proximate mechanisms may be minor constraints to alternative strategy evolution.
        
        Social interactions generate frequency and state-dependent selection that drive evolution of alternative reproductive strategies. Ecology & demography are also important through their infleunce on pay-offs or fitness of the frequency and status dependent fitness functions.
  - - - Helpers get inclusive fitness (depends on time of year). IN june there is a bigger penalty for breeders, yet you have a period where breeding is better and then helping is better. some birds switch from breeders to helpers and vice versa.