2.3 Reproductive animal strategies
Reproduction is the production of a new generation of organisms from an existing
generation. It is a life process that ensures the continued survival of species.
Goal of each species:
To produce the maximum number of surviving offspring while using the least amount of
energy aka reproductive effort.
Asexual reproduction in microscopic animals is energy efficient as it involves only a
single animal however sexual reproduction is much more complex and needs a higher
energy input.
Reproductive strategies:
A. Courtship
B. External vs internal fertilization
C. Ovipary ovovivipary and vivipary
D. Amniotic egg
E. Precocial and altricial development
F. Parental care
A. Courtship
The behaviour and/or signals that are designed to attract another animal for
mating/breeding
Forms of courtship:
1. Simple strategies
- Chemical (pheromones), visual (colours) or auditory stimuli to find mates
- For example: Female moths use pheromones to attract males, Male frogs grunt to
attract females and male birds sing to attract females.
2. Complex strategies - More elaborate form of courtship that is unique to each
species
, Females usually favour males that are:
- Larger
- More elaborate physical features
- Display more energy in courtship activities
This helps females choose better males that can reinforce pair bonding, physical health
and increase survival.
Examples:
● Certain bird species have complex patterns such as Blue Cranes that:
- Use series’ of calls
- Elaborate dances by the males
● Springbok has an annual rut/ period of sexual excitement when animals are in
peak condition. To attract females, males defend territories, attach vegetation
with their horns and deposit urine or dung on display.
- Most young are born within 6 months. The timing ensures that:
- Mothers are in good condition
- Young are born when there’s enough food for them to mature
● Courtship-feeding such as with male African hoopoes that feed insects to their
mates, allowing the female to conserve her energy
How courtship maximises reproduction and increases the chance of strong healthy
offspring:
- Ensure males and females find suitable mates
- Sexual behaviour is timed so that both males and females are ready to mate at
the same
- Females are able to conserve their energy for breeding
B. External vs internal fertilisation
Fertilisation is the joining of the nucleus of an egg and a sperm. The sperm are motile
as they are able to swim but the eggs do not move.
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