Courtship behaviour as a necessary precursor to successful mating.

The idea

Courtship is a sequence of behaviours performed before mating, and each action by one animal is the stimulus for the next response by its partner, so the pair works through a chain of stimulus and response. The chain has to be completed before mating takes place, which is what makes it a necessary precursor. It does several jobs at once. It allows an animal to recognise a member of its own species, so that gametes are not wasted on a mating which could not produce fertile offspring. It allows an individual to recognise the opposite sex, and to judge whether a partner is sexually mature, fertile and receptive, because an animal that does not give the correct response is not ready to breed. It synchronises mating so that sperm and egg are released at the same time, raising the probability of fertilisation, and in many species the display itself triggers ovulation or sperm release.

What earns the marks

• Describing courtship as a chain of stimulus and response in which each action triggers the partner's next behaviour.
• Recognition of a member of the same species, so that mating can produce fertile offspring.
• Identifying a mate that is sexually mature, fertile or receptive.
• Synchronising mating or triggering the release of gametes so that fertilisation is more likely.
• Forming a pair bond that supports the rearing of the young.

Common mistakes and how to put them right

• Describing what the animal does, such as dancing or singing, without saying what the behaviour achieves.

• Writing that courtship 'attracts a mate' and stopping there, which does not name a benefit the mark scheme lists.

• Claiming courtship guarantees fertilisation rather than raising its probability.

• Giving the same benefit twice in different words, such as species recognition and avoiding the wrong species.

• Writing about the survival of the individual when the marks are for reproduction and offspring.

Exam tips

• Turn every behaviour you describe into a consequence, using the words 'so that' to force the benefit out.
• Treat courtship as a self-contained paragraph you can deploy in any essay on reproduction or on interactions between organisms, rather than relying on a published topic list.
• Two- and three-mark courtship questions want separate benefits, not one benefit explained three ways; count distinct ideas before you write.