Lesson focus: Organisms can respond to environmental change through behaviour, acclimatisationWhen a living thing's body adjusts to new conditions, like a climber's body getting used to thin mountain air., range shiftWhen the area where a living thing can be found moves, for example further north as the climate warms. or evolutionary change, but these operate on different timescales.
Compare short-term responses with adaptation across generations and interpret evidence of ecological change.
Build on earlier learning
Competition and adaptationCompetition and adaptation established environment-specific advantages. This lesson asks what happens when the environment itself changes.
You will be successful when you can…
- Distinguish acclimatisation from adaptation.
- Explain range and timing shifts.
- Interpret correlated environmental data.
- Evaluate limits to population response.
Words that carry the science
- acclimatisation
- A reversible change within an individual in response to environmental conditions.
- phenology
- The seasonal timing of biological events such as flowering or migration.
- range shift
- A change in the geographic area occupied by a population or species.
- plasticity
- The ability of one genotype to produce different phenotypes in different conditions.
- migration
- Directed movement, often seasonal, between regions.
- evolutionary rescue
- Adaptation rapid enough to prevent a declining population from becoming extinct.
Separate immediate responses from evolutionary change
01Individuals can alter behaviour and physiology
Animals may move into shade, change activity time or migrate. Plants can alter stomatal opening, root-to-shoot allocation and leaf development. These responses can occur within one lifetime.
acclimatisationWhen a living thing's body adjusts to new conditions, like a climber's body getting used to thin mountain air. and phenotypic plasticityThe ability of a living thing to grow differently in different conditions, like a plant growing taller in shade. can improve performance without changing inherited allele frequencies. They have limits set by physiology, resources and developmental stage.
02Populations can move or evolve
As climate or habitat changes, a population may track suitable conditions through a range shiftWhen the area where a living thing can be found moves, for example further north as the climate warms.. Movement depends on dispersal, habitat corridors and generation time. Fragmented landscapes can prevent tracking.
Evolution requires heritable variation and differential reproduction across generations. If change is faster than dispersal or adaptation, abundance may decline.
03Timing changes can break interactions
Earlier warming may advance flowering, insect emergence or bird breeding. If interacting species shift by different amounts, a phenological mismatchWhen the timing of two linked events in nature gets out of step, such as caterpillars appearing before the young birds that need to eat them. can reduce food supply or pollination.
Long-term records can reveal trends, but association with temperature does not exclude land use, rainfall, observation effort or other drivers. Mechanistic evidence and multiple sites strengthen inference.
Adapting to a warming climate
When the environment changes, organisms may move (range shift), change their behaviour, or the population may evolve by natural selection. Evolution happens one generation at a time, so species with short generations can keep up with fast change more easily.
Each dot is about 25 individuals. Background gets warmer in colour as the climate warms.
Controls
The model is illustrative. Real species can also survive by moving to cooler places, if there is habitat to move into.
Interpret a timing shift
A plant flowers 12 days earlier after a 2 °C warmer spring.
- Identify the response: flowering date changed within the observed population.
- The association is consistent with temperature-sensitive phenologyThe timing of yearly events in nature, such as when flowers open or birds migrate..
- It does not yet show a genetic change; plasticity could explain it.
- Compare common-garden or multi-generation evidence before claiming evolution.
How to make the reasoning visible: Describe the observation first, then distinguish a plausible mechanism from a demonstrated cause.
Compare responses to warming
Classify each response by timescale and mechanism.
| Observation | Likely response type | Timescale | Evidence still needed |
|---|---|---|---|
| Lizard moves into shade | Behaviour | Minutes | Body temperature and repeated observations |
| Human produces more red blood cells at altitude | Acclimatisation | Days to weeks | Reversibility after descent |
| Butterfly range moves north | Range shift | Years to decades | Sampling effort and habitat data |
| Birds breed earlier in warm springs | Phenological plasticity or evolution | Years | Pedigree or common-environment evidence |
| Heat-tolerance allele becomes more common | Evolution | Generations | Heritability and differential reproduction |
Why can migration help without solving long-term habitat loss?
What evidence would distinguish plasticity from inherited change?
Check your understanding
Answer from memory, then check against the suggested answer.
What is acclimatisation?
What is phenology?
What is a range shift?
Explain how earlier caterpillar emergence could reduce breeding success in a bird population.
Explain why short generation time can increase the chance of evolutionary rescue.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Organisms can respond to environmental change by acclimatisation or by evolutionary adaptation.
Compare acclimatisation with evolutionary adaptation.
(4)Suggest a limitation of adaptation when the environment changes quickly.
(1)Total for this question: 5 marks
Command word: For compareA command word: say how two or more things are similar and how they are different., pair each dimension directly: level, timescale, inheritance and limitation.