Climate change is causing global temperatures to rise. Explain how rising temperatures could affect the distribution and survival of a species of butterfly that currently lives only in southern England.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A species of butterfly is currently found only in the south of England. Scientists have recorded that average temperatures in the UK have increased by approximately 1°C over the last century and predict further increases in the coming decades.
Model answer (5 marks)
Rising temperatures make northern areas warmer and more suitable for the butterfly, so the species is likely to expand its range northwards or to higher altitudes.
The shift in distribution means the butterfly can colonise new habitats that were previously too cold.
Warmer conditions also lengthen the breeding season, allowing more generations per year and potentially increasing population size.
However, if temperatures exceed the butterfly’s thermal tolerance, individuals in the southern range may suffer heat stress, leading to reduced survival and possible local extinction.
Finally, climate change can alter the distribution of the butterfly’s host plants; if these plants move north or decline in the south, food availability will drop, threatening the butterfly’s survival even if the climate itself is favourable.
The shift in distribution means the butterfly can colonise new habitats that were previously too cold.
Warmer conditions also lengthen the breeding season, allowing more generations per year and potentially increasing population size.
However, if temperatures exceed the butterfly’s thermal tolerance, individuals in the southern range may suffer heat stress, leading to reduced survival and possible local extinction.
Finally, climate change can alter the distribution of the butterfly’s host plants; if these plants move north or decline in the south, food availability will drop, threatening the butterfly’s survival even if the climate itself is favourable.
Examiner tips
- Use the word ‘shift’ or ‘expand’ to show distribution change. Mention both the benefit (longer breeding season) and the risk (heat stress). Include the food‑plant link to show a full understanding of indirect effects.
Common mistakes
- Assuming the butterfly will simply move without recognising potential food‑plant loss. Ignoring the possibility of local extinction in the original range. Using vague terms like ‘more suitable’ without linking to temperature or breeding season.
Mark scheme (5 marks)
- Rising temperatures mean conditions further north (or at higher altitudes) become more suitable / warmer for the butterfly
- The distribution of the butterfly shifts / expands northwards (or to higher altitudes)
- Warmer temperatures may allow the butterfly to breed / reproduce more successfully or for a longer season
- If temperatures rise too much / beyond the butterfly's tolerance range, survival in the south may decrease / the butterfly may no longer survive in its original range
- Changes in the distribution of the butterfly's food plants / prey due to climate change could reduce food availability and threaten survival
Key terms in this question
distribution · climate change · survival
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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