In short: An adaptation is an inherited feature that helps an organism survive and reproduce in its environment. Adaptations can be structural (body parts), physiological (body processes) or behavioural (actions), like the epicormic buds that let eucalypts regrow after fire.
Starting point: what you already know
- Living things have features that suit their environment (Year 7 and 10 science).
- Living things compete for food, water, space and mates.
- DNA carries the instructions for an organism's features.
Selection pressures
A selection pressure is anything in the environment that affects which organisms survive and reproduce.
| Type | Examples |
|---|---|
| Biotic (living) | Predators, disease, competition for food or mates, availability of prey |
| Abiotic (non-living) | Temperature, water, light, soil nutrients, fire, salinity |
Australia has some strong ones: low rainfall, poor soils, regular bushfires and high temperatures.
Three kinds of adaptation
An adaptation is an inherited feature that helps an organism survive and reproduce in its environment.
| Type | Meaning | Australian examples |
|---|---|---|
| Structural | A body part or shape | Thorny devil's grooved skin. Eucalyptus leaves hang vertically, so less of their surface faces the midday sun. Kangaroo's strong tail and back legs |
| Physiological | How the body works inside | Kangaroos make very concentrated urine to save water. Eucalyptus oil discourages insects. Many wattle seeds only germinate after fire |
| Behavioural | What the organism does | Kangaroos lick their forearms to cool down. Bilbies dig burrows and come out at night. Magpies swoop to guard their nests |
Plants of fire and drought
Many Australian plants are adapted to bushfire.
- Epicormic buds under the thick bark of eucalypts sprout new leaves after a fire.
- Lignotubers, woody swellings at the base of mallee eucalypts, store food and buds to regrow.
- Banksia cones open and release seeds after fire (serotiny).
Aboriginal people have used cultural burning for tens of thousands of years: cool, patchy fires at the right time of year, which shaped many of these landscapes. Many groups now share this knowledge with fire services to reduce fuel and protect country.
Drought adaptations (xerophytes) include small or needle-like leaves, a thick waxy cuticle, sunken stomata, hairs that trap moist air and deep roots.
- Biotic: predators, disease
- Abiotic: heat, drought, fire
- Body shape and parts
- Thorny devil skin
- Hanging eucalypt leaves
- Body chemistry
- Concentrated urine
- Fire-triggered germination
- What it does
- Burrowing, nocturnal
- Licking forearms
- Epicormic buds
- Lignotubers
- Waxy cuticle
Quick summary
- A selection pressure is a biotic or abiotic factor that affects survival and reproduction.
- An adaptation is an inherited feature that improves survival and reproduction.
- Structural: body parts. Physiological: body processes. Behavioural: actions.
- Many Australian plants are adapted to fire (epicormic buds, lignotubers, fire-opened seeds) and drought (waxy cuticle, small leaves).
Quiz
Sign in to take the quiz
13 questions with instant marking. It is free, and your scores are saved to your account so you can carry on from any device.
Turn on JavaScript to sign in and take the quiz.
Try 3 questions now
Which is an abiotic selection pressure?
- A A predator
- B A disease
- C Low rainfall
- D Competition for mates
Show answer
C: Low rainfall
Abiotic means non-living.
A kangaroo licks its forearms to cool down. This is a
- A structural adaptation
- B physiological adaptation
- C behavioural adaptation
- D selection pressure
Show answer
C: behavioural adaptation
It is something the kangaroo does.
Eucalyptus leaves hang vertically. This is a
- A structural adaptation
- B behavioural adaptation
- C physiological adaptation
- D biotic factor
Show answer
A: structural adaptation
It is about the shape and position of a body part.