REPRODUCTIVE ANIMAL STRATEGIES
Reproduction is the production of new generation of organisms from an existing
generation, ensures the continued survival of a species
What is the goal of each species?
1. Maximum number of surviving offspring while using least amount of energy =
reproductive effort
2. Asexual reproduction is energy efficient because involves only single animal
3. Sexual reproduction much more complex and needs much higher energy
input
4. Unique reproductive strategies have developed = breed successfully and then
survive to reproductive age
A- COURTSHIP
Courtship in animals is behaviour and signals that designed to attract another animal
for mating and breeding
What are the different forms of courtship?
1. SIMPLE STRATEGIES
• Chemical (pheromones), visual (brightly coloured body parts) or auditory
stimuli
E.g.
5. Moths produce species- specific pheromones that guide male towards them
6. Male birds sing species- specific song to impress and stimulate the female
7. Most frogs have return to water for mating, once male reach breeding ground
they sing (grunt, croak) to attract females
2. COMPLEX STRATEGIES
• The more elaborate forms of courtship are unique to each species
The females usually favour males that are:
- Larger
- More elaborate physical features
- Display more energy in courtship activity
, REPRODUCTIVE ANIMAL STRATEGIES
This helps female to choose the better male = reinforce pair bonding and promises
healthier offspring
e.g.
8. Certain birds (blue crane) courtship display
9. Springboks have annual rut (period of sexual excitement)
Timing of display = mothers in good condition & young are born when there enough
food to enable them to reach reproductive age
How will courtship maximise reproduction?
• Courtship mechanisms ensure that males and females will find suitable males
e.g. strongest male
• Sexual behaviour in courtship is timed so that male and female are ready for
mating at same time
• Energy expenditure is usually by the male, female conserves her energy for
breeding
= more liking that strong healthy offspring produced
B. EXTERNAL VS INTERAL FERTILISATION
Fertilisation is the joining of the nucleus of an egg and
sperm.
External fertilisation:
Takes place in water & occurs in most aquatic vertebrates
Not an ideal process as:
• Wasteful as huge numbers of eggs are produced, most are eaten
• Fertilisation is not certain
How can external fertilisation maximise reproduction?
Ø Huge numbers of eggs and sperm are released into the water à sperm in
water à female sheds 2000 to 3000 eggs into water à increases chance of
fertilisation
Ø Courtship rules à e.g. many fish swim side by side when releasing their eggs
and sperm
Reproduction is the production of new generation of organisms from an existing
generation, ensures the continued survival of a species
What is the goal of each species?
1. Maximum number of surviving offspring while using least amount of energy =
reproductive effort
2. Asexual reproduction is energy efficient because involves only single animal
3. Sexual reproduction much more complex and needs much higher energy
input
4. Unique reproductive strategies have developed = breed successfully and then
survive to reproductive age
A- COURTSHIP
Courtship in animals is behaviour and signals that designed to attract another animal
for mating and breeding
What are the different forms of courtship?
1. SIMPLE STRATEGIES
• Chemical (pheromones), visual (brightly coloured body parts) or auditory
stimuli
E.g.
5. Moths produce species- specific pheromones that guide male towards them
6. Male birds sing species- specific song to impress and stimulate the female
7. Most frogs have return to water for mating, once male reach breeding ground
they sing (grunt, croak) to attract females
2. COMPLEX STRATEGIES
• The more elaborate forms of courtship are unique to each species
The females usually favour males that are:
- Larger
- More elaborate physical features
- Display more energy in courtship activity
, REPRODUCTIVE ANIMAL STRATEGIES
This helps female to choose the better male = reinforce pair bonding and promises
healthier offspring
e.g.
8. Certain birds (blue crane) courtship display
9. Springboks have annual rut (period of sexual excitement)
Timing of display = mothers in good condition & young are born when there enough
food to enable them to reach reproductive age
How will courtship maximise reproduction?
• Courtship mechanisms ensure that males and females will find suitable males
e.g. strongest male
• Sexual behaviour in courtship is timed so that male and female are ready for
mating at same time
• Energy expenditure is usually by the male, female conserves her energy for
breeding
= more liking that strong healthy offspring produced
B. EXTERNAL VS INTERAL FERTILISATION
Fertilisation is the joining of the nucleus of an egg and
sperm.
External fertilisation:
Takes place in water & occurs in most aquatic vertebrates
Not an ideal process as:
• Wasteful as huge numbers of eggs are produced, most are eaten
• Fertilisation is not certain
How can external fertilisation maximise reproduction?
Ø Huge numbers of eggs and sperm are released into the water à sperm in
water à female sheds 2000 to 3000 eggs into water à increases chance of
fertilisation
Ø Courtship rules à e.g. many fish swim side by side when releasing their eggs
and sperm
