In depth, colour coded summarised notes on the entirety of reproductive animal strategies with diagrams included according to the IEB syllabus for Grade 12 (matric) students.
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REPRODUCTIVE ANIMAL - simple strategies such as
STRATEGIES chemical (pheromones), visual
(brightly coloured body parts)
- reproduction = production of a or auditory stimuli are used
new gen of organisms from an for mates to find each other,
existing gen – ensures can be used alone or in
continued survival of a species combination
- ultimate goal of each animal
species = to produce
maximum number of surviving - examples:
offspring while using least females of some insect
amount of energy, called species produce species
reproductive effort specific pheromones that
- asexual reproduction = guide males towards them
energy efficient (low most frogs have to return
reproductive effort) because to water for mating and
only involves a single animal breeding, once males
- sexual reproduction = much reach breeding ground
more complex, needing a they sing (croak) to
much higher energy input attracts females
(high reproductive effort) male birds advertise when
- unique reproductive strategies they are ready to mate by
developed to ensure singing a species specific
maximum reproductive song that attracts the
success in diff environments – female, once they meet,
enables species to breed male must then impress +
successfully and survive to stimulate female sexually,
reproductive age often by special plumage
- strategy = genetically 2. Complex strategies
determined behaviour - more elaborate forms of
- reproductive strategies are: courtship = unique to each
A. Courtship species
B. External versus internal - females usually favour males
fertilisation that are:
C. Ovipary, ovovivipary and
vivipary
larger
D. Amniotic egg have more elaborate
E. Precocial and altricial physical features
development display more energy in
F. Parental care courtship activity than
other males
A. Courtship - helps female choose better
- = behaviour and/or signals male which can reinforce pair
designed to attract another bonding (NB for parental care)
animal for mating and and promises healthier
breeding offspring (more will survive)
What are the different forms Blue Crane
of courtship? - displays include:
1. Simple strategies a complex and extended
series of calls
, elaborate dances by males - vertebrate species have
Springbok various ways of ensuring
- have an annual rut (a period sperm reach eggs for
of sexual excitement) when fertilisation
animals are in peak condition External fertilisation
- males defend territories w/ - takes place in water, occurs in
loud grunts, attack vegetation most aquatic vertebrates
w/ horns and deposit urine + - not an ideal process as:
dung in a ritualised display is wasteful as huge
- most young born six months numbers of eggs are
later in spring, shortly before produced, most are eaten
rainy season begins fertilisation is not certain.
- timing of this display ensures How can external fertilisation
that: maximise reproduction?
mothers are in good - huge numbers of eggs/sperm
condition are released into water,
young are born when there increases probability of
will be enough food to fertilisation – reproductive
enable them to reach energy expenditure goes
reproductive age almost totally into producing
- rutting strategy results in large number of eggs
breeding only taking place if - courtship rituals are used, e.g.
conditions are favourable many fish swim side by side
African hoopoes when releasing eggs/sperm
- male African hoopoes feed which ensures that male and
insects to mates female gametes are close to
- allows female to save energy each other
for incubating and brooding Internal fertilisation
How will courtship maximise - occurs in terrestrial
reproduction? vertebrates
- courtship ensures males and - male gametes are released
females find suitable mates directly into body of female
- sexual behaviour in courtship (during mating/copulation)
is timed so male and female and fertilise eggs inside the
are ready for mating at same body
time Birds and reptiles
- energy expenditure is usually - mate using a cloaca, a single
by male, female conserves opening located in lower
energy for breeding abdomen
- more likely that strong healthy - during mating, males and
offspring will be produced females line up cloacae for the
transfer of sperm
B. External vs internal Mammals
fertilisation - males of mammals have a
- fertilisation = the joining of penis to introduce sperm into
nucleus of egg and sperm female – known as copulation
- sperm are motile, eggs do not - penis ensures that sperm is
move transferred successfully
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