4a: Sex and Behaviour Flashcards
Comparison of sperm and egg production in relation to number and energy store
Eggs
- finite
- large energy store
Sperm
- infinite
- no energy store
how do females show greater investment in reproduction
Female investment in the egg structure in non-mammals or in the uterus and
during gestation in mammals.
Parental investment is costly but increases theā¦
Probability of production and survival of young
Classification of r-selected (r-strategists) and K-selected (K-strategists) organisms is based onā¦
level of parental investment in offspring and number of offspring produced
Characteristics of r-selected species:
- smaller;
- have a shorter generation time; mature more rapidly;
- reproduce earlier in their lifetime,
- often only once;
- produce a larger number of smaller offspring, each of which receives only a smaller energy input; limited - - - parental care;
- most offspring will not reach adulthood.
Characteristics of K-selected species:
- 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.
r-selection tends to occur inā¦
unstable environments where the species has not reached its reproductive capacity
(K-selection tends to occur in stable environments)
Benefits of external reproduction
very large numbers of offspring can be produced
Costs of external fertilisation
many gametes predated or not fertilised; no or limited parental care; few offspring survive
Benefits of internal fertilisation
increased chance of successful fertilisation; fewer eggs needed; offspring can be retained internally for protection and/or development; higher offspring survival rate
Costs of internal fertilisation
a mate must be located, which requires energy expenditure; requires direct transfer of gametes from one partner to another
