Theory (L4-5) Flashcards
What is greater adult longevity associated with
- Litter size
- Post weaning immature period
- Lactation period
what is the r2 value
if R= 0.65 then body size explains 65% of the total variation in lifespans
what is high juvenile mortality a selection pressure for
lower age reach maturity
larger little sizes
define sexual selection
Increased individual fitness through:
- obtaining a larger number of mates or
- better quality mates.
two processes from which sexual selection can result (a trade off exists)
inter sex (traits that opposite sex prefers) intra sex (traits that enables more mates through elimination comp of same sex)
definitions of male and females
o Females: individuals of species that produce the larger gamete
o Males: individuals that produce the smaller gamete
what circumstance results in large ratio of sexual dimporphism
male/male competition
polygyny
why do males reach adult body size later (delayed maturity)
o Allocate more to growth (as end up larger) = time
o Polygamy vs maturity age
• Male-male competition= selectively advantageous to look immature for longer
• Reduces early comp + better understand social system
• // monogamous species, sexes mature at same age
why is the female gamete larger (anisogamy)
o Therefore internal fertilization and gestation bc makes sense to house embryo and fertilize in sex and location where bigger risk is being made, the bigger investment
• Difference= sea horses where male holds embryos
• Internal fertilization ensures female knows its hers
• Females not reproductively available/fertile during pregnancy and most lactation
o More males compared to available females // male-male competition= risk
what causes the undifferentiated gonads to form testes
sry on y chromo
examples of quantitative variation in humans
muscle mass, fat distribution, facial hair, mortality
general female mammalian case in investment of offspring
o females invest more in offspring (gestation and lactation) = usually increase their fitness more by obtaining better quality mates
general male mammalian case in investment of offspring
o males invest less in offspring and so usually increase their fitness more by obtaining a greater number of mates.
when are sexual selection not natural seelction
ss just due to getting many/quality mates
what are human males attracted to
• Males attracted to things that Indicated of fertility (wait to hip ratio, fat)
