Unit 2 - Topic 4 - Sex and Behaviour - Section A - Parental Investment Flashcards
What is the difference between sperm and egg production in terms of number and energy
Sperm= High number low energy, Egg= low number high engery
Describe greater reproductive investment in females
Female investment in the egg structure in non-mammals or in the uterus and during gestation in mammals.
What does parental investment do
It is costly but increases the probability of production and survival of young
What are the 2 classifications of organisms based on parental investment and number of offspring
R-selected and K-selected
What are the 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.
What are the 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.
When do R and K selection most often occur
R-selection tends to occur in unstable environments where the species has not reached its reproductive capacity, whereas K-selection tends to occur in stable environments
What are the costs and benefits of external fertilisation
Benefits: very large numbers of offspring
can be produced. Costs: many gametes predated or not fertilised; no or limited parental care; few
offspring survive
What are the costs and benefits on internal fertilisation
Benefits: increased chance of successful fertilisation; fewer eggs needed; offspring can be retained internally for protection and/or development; higher offspring survival rate. Costs: a mate must be located, which requires energy expenditure; requires direct transfer of gametes from one partner to another
