KA 4: sex and behaviour: parental investment Flashcards
from which parent is there greater investment?
females
compare the sperm production to egg production in relation to number and energy store
sperm: produced in much larger numbers than eggs
eggs: larger energy store than sperm
describe female investment
in the egg structure in non-mammals or in the uterus and during gestation in mammals.
pro and con of parental investment
-costly
-increases the probability of production and survival of young
what is the classification of r-selected (r-strategists) and K-selected (k-strategists) organisms based on?
level of parental care in offspring and number of offspring produced
describe the characteristics of r-selected species (6)
-smaller
-have a shorter generation time
-mature more rapidly
-produce a larger number of smaller offspring, each of which receives only a smaller energy input
-limited parental care
-most offspring dont reach adulthood
list the characteristics of k-selected species (6)
-larger and live longer
-mature more slowly
-can reproduce many times in their lifetime
-produce relatively few, larger offspring
-high level of parental care
-many offspring have a high probability of surviving to adulthood
when does r selection occur?
in unstable environments where the species has not reached its reproductive capacity
when does k-selection occur?
in stable environments
benefit (1) and cost (3) of external fertilisation
benefit:
-very large numbers of offspring
cost:
-many gametes predated or not fertilised
-no or limited parental care
-few offspring survive
benefit (4) and cost (2) of internal fertilisation
benefit:
-increased chance of successful fertilisation
-fewer eggs needed
-offspring can be retained internally for protection and/or development
-higher offspring survival rate
cost:
-a mate must be located, which requires energy expenditure
-requires direct transfer of gametes from one partner to another