Unit 2: KA4 - Sex and Behaviour Flashcards
Define the term: parental investment
Parental investment is all of the energy costs that parents incur during their reproduction strategy and care of offspring.
Why is parental investment important?
It increases the probability of production and survival of young.
Which parent invests more energy?
The female.
Compare egg cells and sperm cells.
Egg: - 1 at a time - large - large energy store Sperm: - 300 million at a time - small - no energy store
Describe female investment in mammals and non-mammals
Mammals: Uterus and during gestation
Non-mammals: Investment in egg structure
Which two factors are organisms classified as ‘r’ or ‘k’ selected based upon?
- level of parental investment
- number of offspring
What are the differences between ‘r-selected’ and ‘k-selected’ organisms.
r-selected: small level of parental investment, large number of offspring, small size
k-selected: large level of parental investment, small number of offspring, large size
Describe internal and external ferilisation
Internal: egg fertilised inside female’s body
External: egg fertilised outside of female’s body
Describes the costs of External fertilisation
- Many gametes unfertilised/predated
- No or limited parental care
- Few offspring survive
Describe the benefit of external fertilisation
- Very large number of offspring can be produced
Describe the cost of internal fertilisation
- mate must be located, expending energy
- Gametes must be directly transferred to the other partner
Describe the benefits of internal fertilisation
- Increased chance of fertilisation
- fewer eggs needed
- offspring retained internally for protection and development
- Higher offspring survival rate
What are mating systems based on?
How many mates an individual has during one breeding season.
Describe monogamy
The mating of a pair of animals to the exclusion of all others.
Describe Polygamy and its two types.
Individuals of one sex have more than one mate
Polygyny: one male mates exclusively with a group of females
Polyandry: One female mates with a number of males in the same breeding season
Define the term: courtship ritual
A specialised behaviour in animals that attracts a member of the opposite sex and leads to mating
What two factors can successful courtship behaviour be a result of in birds and fish.
- species-specific sign stimuli
- fixed action pattern response
Describe what sexual selection selects for.
characteristics that have little survival benefit for the individual but increases their chances of mating.
Describe sexual dimorphism.
Any physical differences between males and females as a result of sexual selection.
Females becoming inconspicuous, males becoming more conspicuous
Describe reverse sexual dimorphism
When the normally inconspicuous female is larger or more ornate than the male
Describe ‘honest signals’.
Signals revealed by males that indicate:
- favourable alleles
- low parasite burden
Allowing the females to assess genetic quality
Describe lekking
Males will gather to carry out a communal display, encouraging female choice
Define the term ‘satellite males’
subordinate and juvenile males who are found at the fringes of a lek
What does success in male-male rivalry do?
It increases access to females for mating.
What will males fight for?
- Dominance
- Access to females
What will males use to fight?
Weapons eg.
- horns
- antlers
- tusks
