Edexcel A Level (IAL) Biology -5.20 How Climate Change Affects Species- Study Notes- New Syllabus

Effects of Climate Change on Plants and Animals

🌱 Introduction

Climate change is not just about rising temperatures. Two major changes that directly impact living organisms are:

• Altered rainfall patterns
• Shifted seasonal cycles

These changes affect where organisms can live, how they grow, when they reproduce, and how long their life cycles last.

🌦️ Changing Rainfall Patterns

What happens when rainfall becomes irregular?

• Some areas get too much rain, causing floods.
• Others face drought due to too little rain.
• Rainfall becomes unpredictable, disrupting ecosystems.

Effects on Plants

• Water shortage reduces growth, photosynthesis, and seed formation.
• Overwatering or waterlogging can damage roots.
• Drought-tolerant species may outcompete others, changing plant distribution.
• Flowering and fruiting may shift or fail entirely.

Effects on Animals

• Herbivores migrate to find food if plants decline.
• Water-dependent animals struggle during droughts.
• Breeding success may drop due to lack of food or nesting areas.
• Moisture-loving species (frogs, insects) shrink in population.

🍁 Changes in Seasonal Cycles

(Also called phenological shifts – timing of seasons changes)

Effects on Plants

• Earlier springs cause early flowering and leafing.
• Delay or mismatch between flowering and pollinator availability harms reproduction.
• Some plants may start complete life cycles earlier, others may shorten theirs.

Effects on Animals

• Birds may migrate earlier or later than usual.
• Insects may hatch earlier, creating timing mismatches with predators or host plants.
• Breeding seasons shift, which may reduce survival of young ones.
• Hibernation/winter dormancy periods get disturbed.

🗺️ Impact on Distribution of Species

• Species move towards poles or higher altitudes where temperatures suit them.
• Local species decline if they cannot adapt quickly.
• New species may enter an ecosystem, altering food chains.
• Some sensitive species face local extinction due to unsuitable climate.

Impact on Development and Life Cycles

• Temperature and season changes alter growth speed.
• Some organisms complete life cycles faster (e.g., insects).
• Some delay reproduction due to stressful conditions.
• Food availability in early life stages may drop, reducing survival rates.

Memory Trick:
“Climate changes timing, timing changes survival” Helps remember that life cycles depend heavily on seasonal timing.

📊 Summary Table