Unit 2 - Sex and Behaviour Flashcards
Why are eggs much larger and fewer in number than sperm?
Due to the presence of an energy store.
Do males or female make a greater investment in reproduction?
Females.
Why is the investment in reproduction greater in females than in males?
They produce a lower number of larger gametes so their chance of reproductive success is lower and the chance of passing on genes is reduced.
What is the benefit of parental investment?
Increases the probability of production and survival of young.
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;
Many 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.
What kind of environment does r-selection tend to occur in?
Unstable environments.
What kind of environment does K-selection tend to occur in?
Stable environments.
What is the benefit of external fertilisation?
Very large numbers of offspring can be produced.
What are the costs of external fertilisation?
Many gametes are predated or not fertilised
There is no or limited parental care
Few offspring survive
What are the 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
What are the costs of internal fertilisation?
A mate must be located which requires energy expenditure
Requires direct transfer of gametes from one partner to another
What are mating systems based on?
How many mates an individual has during one breeding system.
What is monogamy?
The mating of a pair of animals to the exclusion of all others.
What is polygamy?
Individuals of one sex have more than one mate.
