Unit 10 Behaviour and response in mammals
Key unit competence: Apply acquired knowledge in interpreting behaviour and responses in animals.
Key ideas
- Behaviour is the response of an organism to stimuli from its environment. It helps animals find food, avoid danger, find mates and survive. Behaviour can be innate (inborn, inherited, the same in all members of a species, needs no learning) or learned (acquired through experience, can change).
- Innate behaviours: simple reflex (rapid, automatic response through a reflex arc, e.g. knee jerk, withdrawal from heat); fight-or-flight (adrenaline raises heart rate, breathing rate, blood glucose, dilates pupils and diverts blood to muscles); taxis (directional movement of a whole organism towards (+) or away from (−) a stimulus, e.g. positive phototaxis of moths, negative phototaxis of woodlice); kinesis (non-directional change in the rate of movement or turning depending on stimulus intensity, e.g. woodlice move faster in dry areas and slow down in humid ones).
- Instincts are complex innate behaviour patterns triggered by a sign stimulus (e.g. the red belly of a male stickleback triggers attack; web building by spiders; nest building in weaver birds).
- Learned behaviours: habituation — reduced response to a repeated harmless stimulus (birds ignoring a scarecrow); imprinting — young animals learn to follow the first moving object seen during a short critical period (Lorenz's goslings); classical conditioning — a neutral stimulus becomes linked to a natural one (Pavlov's dogs salivating to a bell); operant conditioning — trial and error with reward or punishment (Skinner's rat pressing a lever); latent learning — learning without immediate reward that is used later (rats exploring a maze); insight learning — solving a new problem by reasoning (chimpanzees stacking boxes).
- Social behaviour occurs in animals living in organised groups (bees, termites, ants, baboons, chimpanzees, wolves). Benefits: protection from predators, cooperative hunting, care of young, division of labour. Costs: competition, spread of disease.
- Communication uses signals: visual (displays, colours), auditory (calls, songs), chemical (pheromones, e.g. ant trails, queen substance in bees) and tactile (grooming). Honeybees use the round dance (food near) and the waggle dance (direction and distance of food far away).
- Altruism: behaviour that benefits others at a cost to the individual (worker bees, alarm calls of vervet monkeys); explained by kin selection (helping relatives who share genes). Courtship: behaviour that ensures mating with the right species, synchronises readiness and reduces aggression. Territoriality: defending an area for food, mates or breeding; spaces individuals and limits population. Dominance hierarchy (pecking order): ranking that reduces fighting; top-ranking animals get first access to food and mates.
- Biological rhythms: circadian (about 24 h, e.g. sleep–wake cycle, controlled by the suprachiasmatic nucleus and melatonin from the pineal gland), lunar/tidal and annual/circannual (breeding, hibernation, migration). An internal biological clock is reset by external cues (zeitgebers) such as light.
- Migration is regular seasonal movement between areas, e.g. wildebeest in the Serengeti–Mara, birds flying from Europe to Africa in winter. Animals navigate using the sun, stars, Earth's magnetic field and landmarks. Benefits: food, breeding sites, avoidance of harsh conditions; costs: energy and risk of death.
Common misconceptions
- "Learned behaviour is passed from parents in genes." No: innate behaviour is inherited; learned behaviour is acquired by experience, though it may be copied.
- "Taxis and kinesis are the same." No: taxis is directional; kinesis changes only the rate of movement or turning.
- "Habituation means the animal is tired." No: it is a learned loss of response to a repeated harmless stimulus; the animal still responds to other stimuli.
- "Altruism cannot evolve." It can, by kin selection: helping relatives passes on shared genes.
Worked examples
Example 1. Woodlice were placed in a choice chamber with dry and humid halves. After 10 minutes, 16 of 20 were in the humid side. Explain the result.
Solution
Woodlice lose water easily. In dry air they move faster and turn more (kinesis), so they spend less time there; in humid air they slow down. Over time most collect in the humid side: 16 ÷ 20 = 80%. This helps them avoid desiccation.
Example 2. A bird flies off when a person approaches, but after many visits it stays near people. Explain.
Solution
The repeated stimulus is harmless, so the response declines: habituation. This saves energy and time for feeding, while the bird still responds to new dangers.
Practice questions
Distinguish between innate and learned behaviour.
Show answer
Innate: inherited, present at birth, same in all members, rigid, no experience needed. Learned: acquired by experience, varies between individuals, can be modified.
Common mistake: Saying learned behaviour is inherited.
Distinguish between taxis and kinesis with examples.
Show answer
Taxis: directional movement of whole organism towards or away from stimulus, e.g. moths to light. Kinesis: non-directional change in rate of movement, e.g. woodlice faster in dry areas.
Common mistake: Calling kinesis a tropism.
Describe the fight-or-flight response.
Show answer
Adrenaline released; heart rate and breathing increase; glucose released from liver; pupils dilate; blood diverted to muscles; hairs stand; digestion slows.
Common mistake: Saying adrenaline slows the heart.
Describe four types of learned behaviour with an example each.
Show answer
Habituation (birds and scarecrow); imprinting (goslings following Lorenz); classical conditioning (Pavlov's dogs); operant conditioning (rat pressing lever); latent learning (rats in maze); insight (chimps stacking boxes).
Common mistake: Giving reflexes as learned behaviour.
State four advantages of social behaviour.
Show answer
Protection from predators; cooperative hunting; division of labour; care and teaching of young; finding food; warmth.
Common mistake: Listing only disadvantages.
Explain the importance of courtship behaviour.
Show answer
Ensures mating with the same species; attracts a mate; synchronises sexual readiness; reduces aggression; shows fitness of mate.
Common mistake: Saying courtship is only for fighting.
Explain how territorial behaviour affects population size.
Show answer
Territories space out individuals; animals without territories may not breed; limits breeding population to resources available; reduces overcrowding and spread of disease.
Common mistake: Saying territories increase the population.
Describe how animals navigate during migration.
Show answer
Using the position of the sun, stars, Earth's magnetic field, landmarks, smell; biological clocks compensate for the sun's movement.
Common mistake: Saying migrating animals move randomly.
Matching and drag-and-drop
Matching
Match each item in column A with the correct answer in column B. Write the letter next to each number.
Column A Column B 1. Pavlov's dogs salivating at a bell is: a. classical conditioning 2. A rapid automatic response such as the knee jerk is a: b. latent learning 3. Learning without reward that is used later is: c. circadian 4. A rhythm of about 24 hours is: d. simple reflex Show answer
1 → a (classical conditioning) · 2 → d (simple reflex) · 3 → b (latent learning) · 4 → c (circadian)
- The bell was linked to food.
- Uses a reflex arc.
- Rats exploring a maze.
- E.g. sleep and waking.
Drag and drop
Choose the correct word or phrase from the box for each gap. One word in the box is not needed.
positive taxis · territoriality · dominance hierarchy · courtship- A ranking order in a group of animals is a .
- Directional movement of a whole organism towards a stimulus is .
- Behaviour that ensures mating with the correct species is .
Show answer
1: dominance hierarchy · 2: positive taxis · 3: courtship
- It reduces fighting.
- E.g. moths to light.
- Displays and songs.
Matching
Match each item in column A with the correct answer in column B. Write the letter next to each number.
Column A Column B 1. Regular seasonal movement of animals between areas is: a. territoriality 2. Behaviour that is inherited and needs no learning is: b. pineal gland 3. Defending an area against others of the same species is: c. migration 4. Melatonin, which affects sleep, is secreted by the: d. innate behaviour Show answer
1 → c (migration) · 2 → d (innate behaviour) · 3 → a (territoriality) · 4 → b (pineal gland)
- E.g. wildebeest.
- The same in all of a species.
- For food and breeding.
- More is made in darkness.
Drag and drop
Choose the correct word or phrase from the box for each gap. One word in the box is not needed.
kinesis · adrenaline · altruism · dominance- The hormone of the fight-or-flight response is .
- A change in rate of movement with stimulus intensity is .
- Behaviour that helps others at a cost to oneself is .
Show answer
1: adrenaline · 2: kinesis · 3: altruism
- It prepares the body for action.
- It is non-directional.
- Explained by kin selection.