Summary by: Kaylin Teneal
REPRODUCTIVE ANIMAL STRATEGIES
GOAL OF EACH SPECIES DEFINITIONS:
- To produce the maximum number of surviving offspring while REPRODUCTION
using the – production
of a new generation of
least amount of energy (this is called the reproductive effort).
organisms from an existing
- Asexual reproduction is energy efficient, whereas sexual reproduction
generation.
needs a much higher energy input.
- Unique reproductive strategies have enabled the species to breed
FERTILISATION – joining of the
successfully and then survive to reproductive age. nucleus of an egg and a sperm.
A. COURTSHIP
Behaviour and/or signals that are designed to attract another animal for mating
and breeding.
Different forms of courtship:
- Simple strategies
o Chemical, visual, or auditory stimuli used for mates to find each other.
o Example – When male frogs reach the breading ground, they sing to attract females.
- Complex strategies
o Unique to each species
o Females usually favour the males that are:
▪ Larger
▪ Have more elaborate physical features
▪ Display more energy in courtship activity
o Example – Blue Cranes’ courtship display which is a elaborate dance by the males.
How well it will maximise reproduction:
- Ensure that males and females find suitable mates.
- So that males and females are ready for mating at the same time.
- Energy expenditure is usually by the male, the female conserves her energy for breeding.
Due to these factors, it is more likely that a strong healthy offspring will be produced.
B. EXTERNAL VS INTERNAL FERTILISATION
, Summary by: Kaylin Teneal
External fertilisation
- Takes place in water and occurs in most aquatic vertebrates
- Not an ideal process as:
o Wasteful as most eggs are eaten, and huge number of eggs are produced.
o Fertilisation is not certain.
- How it can maximise reproduction:
o Huge number of eggs and sperm are released into the water.
o Courtship rituals ensure the female and male gametes are near each other.
- Example – frogs release their eggs into a pond, most are lost due to predation.
Internal fertilisation
- Occurs in terrestrial invertebrates DEFINITIONS:
CLOACA – a single opening
- Most birds and reptiles mate using a cloaca, they line up their cloacae
located in the lower abdomen.
for the transfer of sperm.
- Males of virtually all mammals have a penis to introduce the sperm into
the female (process is called copulation).
- How does it maximise reproduction:
o Fertilisation is more certain as the gametes are placed as
close together as possible.
o Don’t ensure fertilisation but makes it more likely.
o Energy is saved in producing fewer gametes can be used for
other purposes to maximise reproduction.
- Example – dogs/horses
C. OVIPARY, OVOVIVIPARY AND VIVPARY
Terms for reproductive strategies that describe the moment at which the future offspring separates
from a parent.
Ovipary (oviparous – egg producing then released)
- Egg develops inside parent
- Egg yolk is the only food that the developing embryos receive until they hatch from egg.
- Does ovipary in aquatic environments maximise reproduction:
o The eggs are very vulnerable to predation
REPRODUCTIVE ANIMAL STRATEGIES
GOAL OF EACH SPECIES DEFINITIONS:
- To produce the maximum number of surviving offspring while REPRODUCTION
using the – production
of a new generation of
least amount of energy (this is called the reproductive effort).
organisms from an existing
- Asexual reproduction is energy efficient, whereas sexual reproduction
generation.
needs a much higher energy input.
- Unique reproductive strategies have enabled the species to breed
FERTILISATION – joining of the
successfully and then survive to reproductive age. nucleus of an egg and a sperm.
A. COURTSHIP
Behaviour and/or signals that are designed to attract another animal for mating
and breeding.
Different forms of courtship:
- Simple strategies
o Chemical, visual, or auditory stimuli used for mates to find each other.
o Example – When male frogs reach the breading ground, they sing to attract females.
- Complex strategies
o Unique to each species
o Females usually favour the males that are:
▪ Larger
▪ Have more elaborate physical features
▪ Display more energy in courtship activity
o Example – Blue Cranes’ courtship display which is a elaborate dance by the males.
How well it will maximise reproduction:
- Ensure that males and females find suitable mates.
- So that males and females are ready for mating at the same time.
- Energy expenditure is usually by the male, the female conserves her energy for breeding.
Due to these factors, it is more likely that a strong healthy offspring will be produced.
B. EXTERNAL VS INTERNAL FERTILISATION
, Summary by: Kaylin Teneal
External fertilisation
- Takes place in water and occurs in most aquatic vertebrates
- Not an ideal process as:
o Wasteful as most eggs are eaten, and huge number of eggs are produced.
o Fertilisation is not certain.
- How it can maximise reproduction:
o Huge number of eggs and sperm are released into the water.
o Courtship rituals ensure the female and male gametes are near each other.
- Example – frogs release their eggs into a pond, most are lost due to predation.
Internal fertilisation
- Occurs in terrestrial invertebrates DEFINITIONS:
CLOACA – a single opening
- Most birds and reptiles mate using a cloaca, they line up their cloacae
located in the lower abdomen.
for the transfer of sperm.
- Males of virtually all mammals have a penis to introduce the sperm into
the female (process is called copulation).
- How does it maximise reproduction:
o Fertilisation is more certain as the gametes are placed as
close together as possible.
o Don’t ensure fertilisation but makes it more likely.
o Energy is saved in producing fewer gametes can be used for
other purposes to maximise reproduction.
- Example – dogs/horses
C. OVIPARY, OVOVIVIPARY AND VIVPARY
Terms for reproductive strategies that describe the moment at which the future offspring separates
from a parent.
Ovipary (oviparous – egg producing then released)
- Egg develops inside parent
- Egg yolk is the only food that the developing embryos receive until they hatch from egg.
- Does ovipary in aquatic environments maximise reproduction:
o The eggs are very vulnerable to predation
