4.12.4Theme D — Continuity and change
Climate Change: Phenology — IB Biology HL Revision Notes & Topical Questions
5 min read 5 parts Lesson 17 of 18 Unit quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Section 1 of 5Phenology Basics
Warmer springs cause many events to happen earlier.
Definition
- Definition Phenology is the study of the timing of seasonal events in the life cycles of organisms.
Examples
- Examples Dates of flowering, leaf opening, insect emergence, bird migration and egg laying are phenological events.
Cues
- Cues Organisms use temperature, day length and rainfall as cues, and temperature cues change with climate.
Records
- Records Long-term records kept by naturalists and monitoring schemes give data on shifts in timing.
| Event | Observed trend with warming |
|---|---|
| Leaf bud burst | Earlier in spring |
| Insect emergence | Earlier in the year |
| Bird egg laying | Earlier in many species |
| Autumn migration | Later in some species |
| Frog spawning | Earlier in warm springs |
Section 2 of 5How a Mismatch Develops
1
Spring temperatures rise, so oak leaves open earlier and the caterpillars that feed on them hatch earlier.
2
A migratory bird relies on day length or conditions in its wintering area, so its arrival and egg laying change less.
3
The peak demand for food by the nestlings no longer coincides with the peak abundance of caterpillars.
4
Fewer chicks are fed adequately, so breeding success and later population size decrease.
Section 3 of 5Wider Consequences
Wider Consequences
Trophic mismatch
- Trophic mismatch Predators and prey, or plants and pollinators, may respond at different rates and separate in time.
Selection pressure
- Selection pressure Individuals whose timing is better matched to the new conditions may have higher fitness.
Plant effects
- Plant effects Earlier flowering risks frost damage and may occur before pollinators are active.
Monitoring
- Monitoring Phenology is a sensitive indicator of climate change because it responds quickly.
Evidence from records
- Evidence from records Herbarium specimens and decades of first-flowering dates show that many plants in temperate regions now flower days or weeks earlier.
Section 4 of 5Worked Example
Question
- Caterpillar abundance peaks on day 120 and shifts to day 110 under warming, while nestling demand peaks on day 125 and does not shift.
- Calculate the gap before and after.
- Before125 − 120 = 5 days.
- After125 − 110 = 15 days.
- The gap increased by 15 − 5 = 10 days.
Answer Gap rises from 5 to 15 days, a larger mismatch.
Section 5 of 5Exam Checklist & Tips
4.12.4 – Key Points for the Exam
- Phenology The timing of seasonal biological events.
- Mismatch Loss of synchrony between the timing of interacting species.
- Cue An environmental signal used by an organism to time an event.
- Migration Regular seasonal movement between regions.
- Pollinator An animal that carries pollen between flowers.
Common Mistakes
- Stating that all species shift their timing by the same amount.
- Saying that phenology is the study of climate rather than of organisms.
- Ignoring that fixed cues, like day length, do not change with warming.
- Describing a mismatch without naming both interacting species.
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