Environmental changes affect the distribution and survival of both plant and animal species through biotic and abiotic factors. Biotic factors like competition for resources and disease transmission have led to changes in species populations over time, such as the disappearance of pollinating insects and the decline of red squirrel numbers in the UK due to the introduction and spread of grey squirrels who outcompete reds for food and carry squirrel pox virus to which they are immune but kills reds. Non-biotic environmental changes in temperature, oxygen levels, water, and light availability from sources like pollution have also impacted species distributions.

1. Environmental changes

2. (a) Changes in the environment affect the
distribution of living organisms.
• For example, the changing distribution of some bird
species and the disappearance of pollinating insects
including bees.
(b) Animals and plants are subjected to
environmental changes.

3. Changes may be caused by living or non-living factors.
Non-living (abiotic) factors:
Living (biotic) factors:
• Temperature
• Light
• Oxygen – air polution
• Water
• Disease
• Predation
• Competition
– for: food, light, water, space.

4. Native to the UK
(indigenous)
Introduced to the UK in the
19th century

5. 1945

6. 2010
What are the main
changes?
Why the changes?

8. Greys carry disease
60% of grey squirrels in England and Wales carry
the squirrel pox virus. While they are immune to the
disease it is deadly to reds.
Greys crowd out the reds
Greys eat seven times more food per hectare than
reds. They aggressively compete for food, crowding
out reds until eventually only greys are left.

9. 8000 BC

10. 2015 AD