topic 7 - ecology

• Individual


  Part of a species, lives in its habitat within a population
• Population


  Many different populations interact in the same habitat, creating a community
• Ecosystem


  Interaction of a community with non-living (abiotic) parts of the environment
• Organism


  Adapted to live in the conditions of their environment
• Organisms need the same resources


  They compete for it
• Plants compete for


  • Light
  • Space
  • Water
  • Mineral ions
• Animals compete for


  • Space
  • Food
  • Water
  • Mating partners
• Interdependence


  Organisms in a community depend on other organisms for vital services
• Interdependence examples


  • Birds take shelter in trees
  • Flowers are pollinated with the help of bees
• Removal or addition of a species


  Affects the populations of others greatly, as it changes prey or predator numbers
• Stable community


  All the biotic (living) and abiotic (non-living) factors are in balance, population sizes remain roughly constant
• When biotic factors are lost it is very difficult to replace them
• Abiotic factor


  Non-living factor
• Abiotic factors that can affect a community


  • Light intensity
  • Temperature
  • Moisture levels
  • Soil pH and mineral content
  • Wind intensity and direction
  • Carbon dioxide levels
  • Oxygen levels for aquatic animals
• Light intensity


  Required for photosynthesis, affects the rate of plant growth
• Temperature


  Affects the rate of photosynthesis
• Moisture levels


  Both plants and animals need water to survive
• Soil pH and mineral content


  Affects the rate of decay and how fast mineral ions return to soil, different species thrive in different nutrient levels
• Wind intensity and direction


  Affects the rate of transpiration in plants, which affects temperature and photosynthesis
• Carbon dioxide levels


  Affects the rate of photosynthesis in plants, and the distribution of organisms
• Oxygen levels for aquatic animals


  Vary greatly in water, most fish need high concentrations to survive
• Biotic factor

  Living factor
• Organisms


  • Have adaptations that allow them to survive in the conditions where they live
• Types of adaptations


  • Structural
  • Behavioural
  • Functional
• Structural adaptation


  Shape or colour of a part of an organism
• Structural adaptations


  • Sharp teeth of a carnivore to tear meat apart
  • Camouflage, such as the tan/brown colour of a lionesses coat, to avoid prey from spotting her
  • Species in cold environments may have a thick layer of fat for insulation
• Behavioural adaptation


  The way an organism behaves
• Behavioural adaptations


  • Individuals may play dead to avoid predators
  • Basking in the sun to absorb heat
  • Courting behaviour to attract a mate
• Functional adaptation


  Involved in processes such as reproduction and metabolism
• Functional adaptations


  • Late implantation of embryos
  • Conservation of water through producing little sweat
• Extremophiles


  Organisms that live in environments which have extreme conditions such as high temperatures, pressures or salt concentrations
• Extremophiles example


  • Bacteria which live in deep sea vents where the pressure is very high
• Adaptations for cold climates


  • Smaller surface area to volume ratio to reduce heat loss
  • Lots of insulation (blubber, fur coat)
• Adaptations for dry climates


  • Adaptations to kidneys so they can retain lots of water producing very concentrated urine
  • Being active in the early morning and evenings when it is cooler
  • Resting in shady areas
  • Larger surface area ratio to increase heat loss
• Plant adaptations


  • Curled leaves to reduce water loss
  • Extensive root systems to take in as much water as possible
  • Waxy cuticle to stop water evaporating
  • Water storing tissue in stem
• Food chain


  Feeding relationships shown by a series of organisms where each one feeds on the one below it
• Producer


  Photosynthetic organism (usually a green plant or algae) that makes glucose through photosynthesis, which is used to make other biological molecules that make up the biomass
• Population cycles

  Stable community will show cycles between predators and prey, where the prey population increases, then the predator population increases, then the prey population decreases, then the predator population decreases
• Environmental changes affect the distribution of species in an ecosystem:

  • Temperature: Climate change may lead to insects migrating to places in the world which are becoming hotter
  • Water availability: Populations will migrate to find water
  • Atmospheric gas composition: Certain pollutants can affect the distribution of organisms, e.g lichen cannot grow in places where sulfur dioxide is present.

  These changes may be seasonal, geographic or caused by human interaction.