Animal reproductive strategies
Reprod strategies are genetically determined behaviours
To produce max number of offspring with min amount of energy
Which strategies ensure max reprod success in different environments?
- Courtship behaviour
- Internal / external fertilisation
- Ovipary, vivipary and ovovivipary
- Amniotic egg
- Parental care
Courtship = rituals & actions performed to attract a mate
e.g. frogs return to water for mating = males sing (croak) to attract females – each species
has own song that only attracts females; same species
How will courtship maximize reproduction?
- to find suitable mates - the strongest male
- timing: male & female are ready for mating - same time
- energy expenditure is usually by the male (female conserves energy - breeding)
Internal fertilization: egg fertilized inside body of female animal
Advantages: 1. gametes not exposed – dry conditions 2. fertilization occurs = contained environment
3. gametes not lost to predation or washed away by water environment
e.g. birds/ reptiles mate internally by the male/ female lining up their cloacae ( opening in lower
abdomen) for transfer sperm
External fertilization: gametes fuse outside parents body in a moist environment
Advantages: 1. no additional energy – parental care 2. male organisms don’t need special organs –
insert sperm into female 3. water facilitates fertilization: sperm swim + prevents desiccation
e.g. Aquatic vertebrates: like fish swim side by side when release eggs + sperm – ensure male/female
gametes close to each other
OVIPARY = Oviparous organisms – eggs develop outside of parent (internally/ externally
fertilised) ->
In aquatic organisms: Eg: catsharks lays egg cases = mermaid purses. Egg cases
contains embryo & yolk supply = embryo survives on yolk supply -> embryo well
protected, no need large num of eggs
advantages – parental care increases reproductive success, birds protect/ incubate/
feed young, shells protect from dehydration/ predation/ damage
disadvantages - energetically demanding, embryos not protected
Reprod strategies are genetically determined behaviours
To produce max number of offspring with min amount of energy
Which strategies ensure max reprod success in different environments?
- Courtship behaviour
- Internal / external fertilisation
- Ovipary, vivipary and ovovivipary
- Amniotic egg
- Parental care
Courtship = rituals & actions performed to attract a mate
e.g. frogs return to water for mating = males sing (croak) to attract females – each species
has own song that only attracts females; same species
How will courtship maximize reproduction?
- to find suitable mates - the strongest male
- timing: male & female are ready for mating - same time
- energy expenditure is usually by the male (female conserves energy - breeding)
Internal fertilization: egg fertilized inside body of female animal
Advantages: 1. gametes not exposed – dry conditions 2. fertilization occurs = contained environment
3. gametes not lost to predation or washed away by water environment
e.g. birds/ reptiles mate internally by the male/ female lining up their cloacae ( opening in lower
abdomen) for transfer sperm
External fertilization: gametes fuse outside parents body in a moist environment
Advantages: 1. no additional energy – parental care 2. male organisms don’t need special organs –
insert sperm into female 3. water facilitates fertilization: sperm swim + prevents desiccation
e.g. Aquatic vertebrates: like fish swim side by side when release eggs + sperm – ensure male/female
gametes close to each other
OVIPARY = Oviparous organisms – eggs develop outside of parent (internally/ externally
fertilised) ->
In aquatic organisms: Eg: catsharks lays egg cases = mermaid purses. Egg cases
contains embryo & yolk supply = embryo survives on yolk supply -> embryo well
protected, no need large num of eggs
advantages – parental care increases reproductive success, birds protect/ incubate/
feed young, shells protect from dehydration/ predation/ damage
disadvantages - energetically demanding, embryos not protected
