This document provides an in depth explanation on the specific strategies used by animals to reproduce. It is subdivided into categories, explaining courtship, fertilization techniques, reproductive strategies in terms of the development of the foetus, and more.
,GOAL OF EACH SPECIES
• Reproductive effort: produce the maximum number of surviving offspring while
using the least amount of energy
• Asexual reproduction is energy-efficient but limited to lower organisms
• Sexual reproduction in vertebrates is energy-intensive
• Species develop diverse reproductive strategies for success in breeding and
survival to reproductive age
• Strategies: courtship; external vs internal fertilisation; ovipary, ovovivipary and
vivipary; amniotic egg; precocial and altricial development; parental care
COURTSHIP
• The behaviour and/or signals that are designed to attract another animal for
mating and breeding
• Courtship maximises reproduction by:
- Ensures males find suitable females (strongest)
- Sexual behaviour is timed (male and female are ready for mating at same
time)
- Energy expenditure is by the male; female converses energy for brooding
1. Simple strategies
• Chemical (pheromones)
• Visual (brightly coloured body parts)
• Auditory stimuli
> Females of insect species (moths) produce species specific pheromones that
guides males towards them
> Frogs return to water for mating and breeding. Males sing (grunt and croak) to
attract females. Each species has its own song that attracts same-species
females
> Male birds sing species-specific songs that attracts the female. The male
must then impress and stimulate the female sexually (special plumag)
, 2. Complex strategies
• Unique to each species
• Females favour males that are usually:
- Larger; elaborate physical features; display more energy in courtship activity
than other males
- This helps females choose males which can reinforce pair bonding (for
parental care) and promises healthier offspring
• Blue cranes: complex & extended series of calls and elaborate dances by
males
• Springbok: annual rut (period of sexual excitement) when in peak condition.
Males defend territories with loud grunts, attack vegetation with their horns,
and deposit urine and dung in a ritualised display to attract females
- Born in spring before the rainy season because:
- Mothers are in good condition
- Young are born when there is food that enables them to reach
reproductive age
• African hoopoes: males feed insects to their mates (female can save energy
for incubating and brooding)
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