Ecology

• Habitat

  The place where an organism lives
• Population

  All of the organisms of a particular species that live in a habitat
• Community

  All the populations of different species that live together in a habitat
• Factors in the environment

  • Biotic factors (living)
  • Abiotic factors (non-living)
• Ecosystem

  The interaction of a community of living organisms with the non-living parts of their environment
• Competition

  • Organisms need limited resources to survive
  • Organisms have to compete with each other to get enough of these resources
• Resources organisms compete for

  • Space (territory)
  • Food
  • Water
  • Mates
• Resources plants compete for

  • Light
  • Space
  • Water
  • Mineral ions from soil
• Interdependence

  All species depend on other species in some way
• Biotic factors

  Any living factor that affects another organism or that shapes the ecosystem in some way
• Abiotic factors

  The non-living parts of the environment that can affect organisms
• Abiotic factors

  • Light intensity
  • Temperature
  • Carbon dioxide concentrations
  • Moisture levels
  • Wind intensity and direction
  • pH
  • Mineral content of soil
• Increase in temperature

  Increases the rate of photosynthesis
• Increase in temperature

  Animals have to spend less energy staying warm, so they can use more energy for growth or spend less time searching for food
• Biotic factors

  • Predation
  • Competition
  • Disease/ new pathogens
  • Availability of food
• Structural adaptations

  • Physical features of an organism, like shape or colour
• Structural adaptations

  • Seals and walruses having a rounded shape and gray-brown colour to conserve body heat and camouflage
• Behavioral adaptations

  • The way an organism behaves or acts
• Behavioral adaptations

  • Elephants flapping their ears and spraying themselves with water to cool down
  • Swallows and other birds migrating to warmer countries in winter to avoid cold and lack of food
• Functional adaptations

  • Processes going on inside an organism's body, like metabolism or reproductive system
• Functional adaptations

  • Desert animals conserving water by producing little sweat and concentrated urine
  • Camels accumulating fat in humps to release water later
• Extremophiles are microorganisms like bacteria or archaea adapted to live in extreme environments
• Extremophiles

  • Living at high temperatures in hot springs
  • Living in high salt concentrations in salt lakes
  • Living at high pressures in deep sea vents
• Food chain

  Shows what gets eaten by what in an ecosystem
• Food chains are a simplified version of a food web because they don't show all of the interactions, just one chain
• Food chain

  • Starts with a producer (photosynthetic organism like a green plant or alga)
  • Has primary consumers (eat the producers)
  • Has secondary consumers (feed on the primary consumers)
  • May have tertiary consumers (feed on the secondary consumers)
• As energy gets passed up the different levels of the food chain, most of it gets lost
• Arrows between levels in a food chain

  Represent the flow of energy up the chain
• Predator prey cycle

  Graph showing how the populations of a predator and its prey vary together over time
• In a predator prey cycle, the change in the predator population always lags slightly behind that of the prey
• Predator prey cycle

  1. Prey population increases when predator population is low

  2. Predator population increases when prey population is high

  3. Predator population decreases when prey population is low

  4. Prey population increases again when predator population is low
• The main reason for the predator prey cycle is that it takes a long time for entire populations to increase or decrease
• Abundance

  Abundance refers to how many organisms there are

  
• Distribution

  Distribution refers to where the organisms are

  
• Sampling

  ‘Sampling’ is where ecologists only measure a subset of the organisms, and use that subset to make predictions about the whole population. 

  
• Sampling methods

  • Quadrats — measure abundance
  • Transects — measure how distribution changes
• Quadrats

  Quadrats are square frames, that have been subdivided into lots of smaller squares. We can use them to sample a habitat and estimate the size of a population.

  
• Water cycle

  1. Energy from the sun causes water evaporation

  2. Water vapor accumulates and condenses into clouds

  3. Water falls back down as precipitation

  4. Water seeps into soil, flows into rivers, or is taken up by plants

  5. Cycle repeats
• Carbon cycle

  1. Carbon is stored in the air as carbon dioxide, in plants as biological molecules, in the soil with microorganisms, in fossil fuels underground, and in animals as biological molecules

  2. Plants take in carbon dioxide from the atmosphere and convert it into biological molecules through photosynthesis

  3. Carbon can be passed back to the atmosphere through respiration or passed on to animals

  4. When plants and animals die, microorganisms can decay them and release carbon dioxide, or they can be converted into fossil fuels

  5. Fossil fuels can be burned by humans to produce carbon dioxide
• Biodiversity

  The variety of different species on earth or within an ecosystem