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Parental Investment Theory & Sexual Selection - Coggle Diagram
Parental Investment Theory
& Sexual Selection
Parental Investment Theory
Trivers (1972)
Bateman - focused on anisogamy (differential investment in sperm/egg)
Trivers - investment in gamete
and
PI
Main principles
The greater-investing sex is more selective
The less-investing sex will compete for access to the greater-investing sex
Sex-role reversed species
NA shorebirds - males more choosy/investing; females larger, more aggressive, and ornamented
Seahorses - high male investment, but females still choosier; better explained by monogamous mating
Optimal strategies to maximise inclusive fitness
F --> quality over quantity, RS doesn't increase with partners
M --> quantity over quality, RS increases with partners
Sexual Selection
NS VS SS
Intersexual selection VS intrasexual selection
Intersexual selection
Honest signalling
Trade off, signalling genetic quality
Bateman's principle
Variability in RS is greater in males than females
Males have greater variance in reproductive success (number of offspring)
Males have greater variance in mating success (number of sexual partners)
Stronger RS-MS relationship for males
Polygyny advantage
Bateman-Williams-Trivers Theory of SS
'Eager' males, 'discriminating' females
Polygamy appeals more to males
Reproductive variability (RV)
Differences in RS within a sex of a species
Polygynous mating systems
High RV --> greater sexual dimorphism
Occurence in primates - gibbons VS humans VS gorillas
Sperm competition
4 methods - CTAM
Testes mass to body mass ratio
Soay sheep; gorillas/humans/chimps
Monogamous mating systems
Less RV difference --> less intrasexual competition --> less sexual dimorphism
Gibbons, owl monkeys, tamarins
Human mating systems
High monogamy, high male PI
Polygyny still persists despite culture - optimal choice
Females sexually mature before males - typical of polygynous species
Nuptial gifts and female sexuality as a precious commodity
Biparental care
Human children more costly; PC helps to boost direct fitness
Male choosiness for the best investor
Intrasexual selection
Secondary male sexual characteristics - intrasexual selection or intersexual selection?
Vocal and facial masculinity - hypermasculinity aversion
Mate-choice copying
Mate preferences
Male preferences -
RFAC YASFVW
2 hypotheses about female beauty standards
The Beauty Myth - Naomi Wolf
Evolved beauty standards
Universality of preferences
Infant preferences
Female preferences -
RASA FAVS
Social Structural Hypothesis - Structural Powerlessness Hypothesis
Persistence, sufficiency/satisfaction, cultural inertia
Mate-choice copying
Jones et al. (2007)
Short-term mating
Sex diffs in preferences
Predictions based off PIT - proven by Buss
Men seek ST relationships more
Men more willing with shorter time
Men more interested in more partners
Lowering standards
Homosexual couples not constrained by compromise
Pornography VS romance novels
Commitment
Chatbots - gullibility, etc.
Extramarital affairs
Dissatisfaction, sexual variety
Prostitution
The problem with socio-cultural interpretations
Female ST mating
Risky! Less desirable, pregnancy w/o mate
Adaptive benefits - ROPGSM
Resource hypothesis
Obtaining/evaluating LT mate
Paternity confusion
Genetic benefits
Sexy Son hypothesis
Mixed reproductive strategy
M and F differ in preferences based on adaptive problems in evo history - RMPT
Preferences can also be fickle
Runaway Selection Hypothesis - Fisher (1930)