BehaviourOxford AQA IGCSE Biology: Revision notes

Sexual reproduction requires an animal to find and select a suitable mate. This often involves courtship behaviours — displays or actions that advertise an individual's quality to a potential mate (for example, its strength, health or genetic fitness), increasing the chance of a successful pairing.

Different species use different mating strategies:

The strategy an animal uses affects how much time and energy it invests in courtship and in caring for its offspring.

Some animals have developed special behaviours for rearing their young, known as parental care. Parental care can be a successful evolutionary strategy because it:

• Increases the chance of survival of the offspring (by protecting them from predators, feeding them, or teaching them skills)
• Increases the chance of the parents' genes being passed on, since offspring that survive to reproduce carry copies of the parents' genes into the next generation

However, parental care can involve risks to the parents:

• Parents may face increased predation risk while defending or feeding their young, as this can make them more visible or leave them less able to flee
• Parents may use up energy and body reserves caring for offspring, which can reduce their own chance of survival or ability to reproduce again
• Parents may be injured while directly defending offspring against predators or rivals

So although parental care improves the chances of offspring surviving, it comes at a cost to the parent's own survival and future reproduction.

Animals show several different types of behaviour, including innate behaviour and imprinting.

Innate behaviour is behaviour that an animal performs without having to learn it — it is inherited and present from birth (or hatching), and is triggered automatically by a particular stimulus. Innate behaviours are typically the same in all members of a species. An example is a newly hatched turtle automatically moving towards the sea.

Imprinting is a type of learning that occurs during a specific, early critical period in an animal's life, in which a young animal forms a strong, rapid attachment to the first moving object it sees (normally a parent), and afterwards follows and copies it. Unlike innate behaviour, imprinting depends on early experience and can only happen during a narrow window of time early in life.

Three further named types of behaviour involve learning through experience:

• Habituation: an animal learns to ignore a repeated stimulus that has no important consequence for it. For example, an animal may initially be startled by a loud but harmless repeated noise, but stops reacting to it once it learns the noise is not a threat.
• Classical conditioning: an animal learns to associate two stimuli together, so that a response originally triggered by one stimulus becomes triggered by a second, previously unrelated stimulus. A classic example is a dog learning to associate the sound of a bell with the arrival of food, eventually salivating at the sound of the bell alone.
• Operant conditioning: an animal learns to associate a behaviour with a reward or punishment, making it more or less likely to repeat that behaviour. For example, an animal that receives a food reward after performing an action becomes more likely to repeat that action.

Humans make use of conditioning (mainly operant conditioning) when training captive animals for specific purposes. Two named examples are:

• Sniffer dogs: trained using rewards to associate detecting a particular scent (such as drugs or explosives) with a reward, so they repeatedly and reliably indicate when they detect that scent.
• Police horses: trained using conditioning to remain calm in situations that would normally be alarming, such as loud crowds or noises, by gradually exposing them to these stimuli alongside a reward or reassurance, so they learn not to react with fear.

In both cases, repeated training strengthens the learned association between a behaviour (or lack of a fear response) and the outcome (a reward), making the desired behaviour reliable.

Animals use a variety of types of signal to communicate within the animal kingdom. Three named types are:

These signals allow animals to convey information — such as their location, identity, readiness to mate, or the presence of danger — to other members of their species (or sometimes to other species) without needing direct contact.