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Adaptation and Competition (Higher)
 

Animal Adaptations | Plant Adaptations  | Competition and Populations

Factors affecting the size of a Population
 
Animal Adaptations

The organisms living in a particular habitat can only do so because they have features, adaptations, which enable them to survive in the conditions there.

Some adaptations of animals that can survive in the cold conditions of the arctic and in the arid (dry) conditions of a desert, where the temperature can be well below freezing at night and up to 50ºC during the day, are shown below.
Adaptations to survive in arctic conditions
Adaptations to survive in desert conditions
  • Thick layer of fur for insulation, e.g. polar bears, seals.
  • Have markings to camouflage them against the sand.
  • Large amount of body fat for insulation, e.g. polar bears, seals.
  • Can survive long periods without water by producing dry faeces and small quantities of concentrated urine.
  • Often have white fur for camouflage, e.g. artic fox.
  • Camels have long eye-lashes to stop sand blowing into their eyes and large feet so they don’t sink into the sand.
  • Generally have a small surface area to volume ratio to reduce heat loss.
  • Generally have a large surface area to volume ratio so they lose more heat to their surroundings

Animals also show adaptations for the type of food they eat.

Carnivores such as cats and dogs have large canine teeth. Birds of prey have large talons and sharp beaks.
Plant Adaptations

Plants that live in arid conditions may have long roots to reach underground water, or lots of fine roots near the surface to absorb morning dew.

Some have thick waxy cuticles to reduce water loss from their leaves.

Cacti have large stems that can store water, and they have spines instead of leaves to reduce water loss.
Competition and Populations

Organisms compete with each other for resources.

Animals compete for space, water and food.

Plants compete for light, space, water and nutrients from the soil.
 

A population is the number of organisms of a particular species living in a habitat.

A community is the total number of all organisms living in the same habitat.

Within a community the population of an organism will be limited by the amount of food available.
 

In a stable environment the populations of predators and prey will fluctuate in a regular pattern, as shown in the graph.

If the population of prey increases, there will be more food for predators, so their population will also increase.

However, as the population of predators increases more food is needed so eventually the population of prey will decrease.

This means less food for the predators, so their population falls again.

12.1_pop_change

Factors affecting the size of a Population

  • Amount of food available
  • Competition for food or resources
  • Disease
  • Number of predators
  • Competition for light (plants)
  • Number of grazing animals (plants)
  • Amount of nutrients or water in soil (plants)