2.4a Parental Investment

Question 1

Where is there greater investment: sperm or egg? and why?

Answer 1

• greater investment by female
• Female investment in the egg structure in non-mammals or in the uterus and during gestation in mammals.

Question 2

benefit and downside of parental investment?

Answer 2

• benefit - increases the probability of production and survival of young
• downside - costly

Question 3

What are characteristics of r-selected species?

Answer 3

• smaller
• shorter generation time
• mature more rapidly
• reproduce earlier in their lifetime, often only once
• larger number of smaller offspring
• small energy input into offspring
• limited parental care
• most will not reach adulthood

Question 4

What are characteristics of k-selected species?

Answer 4

• larger
• live longer
• mature more slowly
• can reproduce many times in their lifetime
• produce few, larger offspring
• high level parental are
• many offspring have a high probability of surviving to adulthood

Question 5

When does r-selection occur?

Answer 5

• unstable environment where the species has not reached its respoductibve capacity

Question 6

When does k-selection occur?

Answer 6

stable environments

Question 7

What are the benefits and costs of external fertilisation?

Answer 7

Benefits:
- very large numbers of offspring can be produced

Costs:
- many gametes predated of not fertilised
- no or limited parental care
- few offspring survive

Question 8

What are the benefits and costs of internal fertilisation?

Answer 8

Benefits:
- 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 energy expenditure
- requires direct transfer of gametes from one partner to another