a) Parental Investment
Look at the following statements. For each, decide whether you agree or disagree and justify your response.
Parental Investment
Compare the differences between different parenting styles and how these affect survival chances
Success Criteria
Describe the differences between male and female gametes
Describe the differences and explain the benefits of r and k selected species
Explain the differences between internal and external fertilisation
Comparison of parents
Comparison of parents
Parent | Number of gametes produced | Size of energy store |
Male | | |
Female | | |
Large
Small
Small
Large
Gamete production
Females - 1 egg per month
Males
Parental investment
When it comes to parental investment, in most species, it is the female who invests the most.
Females also have an investment in the egg structure in non-mammals or in the uterus and during gestation in mammals.
Parental investment is costly but increases the probability of production and survival of young.
Classification of parenting
Parental behaviour can be classified in one of two groups: r-selected or K-selected.
Classification of parenting
What do you think are the features of each type of species?
Classification of parenting
What do you think are the features of each type of species?
Size
Generation time
Maturation rate
Amount of reproduction
Number of offspring produced
Level of parental care
Energy input by parents
Offspring survival probability
Classification of parenting
Feature | R-selected species | k-selected species |
Size |
|
|
Generation time |
|
|
Maturation speed |
|
|
Amount of reproduction |
|
|
Small with short lifespan
Large with long lifespan
Short
Long
Quick
Slow
Often only once
Multiple times
Classification of parenting
Feature | R-selected species | k-selected species |
Number of offspring produced |
|
|
Level of parental care |
|
|
Energy input by parents |
|
|
Offspring survival probability |
|
|
Large amount of small offspring
Small amount of large offspring
Limited
High
Small
Large
Low
High
Classification of parenting
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.
Internal Fertilisation
The process by which the sperm and egg nuclei fuse inside the female.
External Fertilisation
The process by which the sperm and egg nuclei fuse outside the female.
Internal vs External Fertilisation
| Benefits | Costs |
Internal fertilisation |
|
|
Internal vs External Fertilisation
| Benefits | Costs |
External fertilisation |
|
|