Unit 8: Ecology

• Ecology


  The study of interactions between living and nonliving factors in the environment
• Living factors (biotic factors)

  • Parasites
  • Other organisms
• Nonliving factors (abiotic factors)

  • Water
  • Temperature
  • Soil
• Behavior


  A response to stimuli in the environment
• Types of behavior


  • Innate (inherited, automatic, consistent)
  • Learned (changes with experience and environment)
• Innate behavior


  • Migration
• Learned behavior


  • Language
• Natural selection favors innate and learned behaviors that increase survival and reproductive success
• Tropism


  A plant's response to environment stimuli
• Types of tropisms


  • Phototropism (growth in response to light)
  • Photoperiodism (blooming in response to light)
  • Gravitropism/geotropism (growth in response to gravity)
  • Hydrotropism (growth in response to water)
• Tropism direction


  • Positive (towards stimulus)
  • Negative (away from stimulus)
• Transpiration


  The evaporation of water from plant leaves
• Water is absorbed at the roots and travels to the leaves where photosynthesis happens (possible because of cohesion and adhesion)
• Energy flow terms


  • Autotroph
  • Heterotroph
  • Consumer
  • Producer
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
  • Quaternary consumer
  • Herbivore
  • Carnivore
  • Omnivore
  • Decomposer
  • Detritivore
• Food chain


  Shows the feeding relationship between organisms, with the sun as the ultimate source of energy
• Trophic level


  A level in a food chain, with the 1st trophic level always being a producer
• Food chains usually only go to 4 or 5 trophic levels due to insufficient energy
• All trophic levels connect to decomposers
• In a food chain, the arrows point in the direction that energy moves
• Endotherms


  Generate heat to maintain their body temperature, requiring more food
• Ectotherms


  Do not regulate their own body temperature, only eating for their own energy needs
• Energy pyramid


  Represents the amount of energy at each trophic level in a food chain, with the amount of energy greatest at the first trophic level and decreasing with each successive level
• 10% rule


  Roughly 10% of an organism's energy is passed to the next trophic level, with the rest lost to the environment as heat
• Food web


  Shows interconnected food chains in an ecosystem, where organisms can occupy multiple trophic levels
• Biomagnification


  Toxins build up in an organism's tissues and are passed to the next trophic level
• Energy Flow Practice


  1. Identify producers

  2. Identify autotrophs

  3. Identify herbivores

  4. Identify carnivores

  5. Identify omnivores

  6. Identify missing heterotrophs

  7. Identify top of trophic pyramid

  8. Interpret arrow from grass to grasshopper

  9. Create energy pyramid from food web
• Nutrient cycling (biogeochemical cycles)


  Nutrients move between living things and the atmosphere, continually changing forms but not being created or destroyed
• Carbon cycle


  Carbon enters the food chain through photosynthesis, returns to the abiotic reservoir through respiration and combustion, with human impact from burning fossil fuels and deforestation
• Nitrogen cycle


  Nitrogen enters the food chain through nitrogen fixation by bacteria, recycled through decomposition and nitrifying bacteria, with human impact from fertilizer runoff and pesticides
• Phosphorus cycle


  Phosphorus enters the food chain through erosion, recycled through decomposing bacteria and fungi, with human impact from fertilizer runoff
• Water cycle


  Water moves between abiotic reservoirs and the food chain through precipitation, plant uptake, transpiration, evaporation, and runoff, with human impact from pollution and deforestation
• Population


  A group of organisms of the same species living in the same area, relying on the same resources and interacting
• Factors affecting population size

  • Abiotic factors (sunlight, temperature, water, nutrients)
  • Biotic factors (prey, competitors, predators, parasites)
  • Intrinsic factors (adaptations)
• Population dispersal and density

  • Clumped (most common)
  • Random
  • Uniform (territoriality)
• Survivorship curves


  • Type I (high death rate in post-reproductive years)
  • Type II (constant mortality rate throughout lifespan)
  • Type III (very high early mortality rate but the few survivors then live long)
• 1. selected


  Late reproduction, few offspring, invest a lot in raising offspring, Type I survivorship curve
• 1. selected


  Early reproduction, many offspring, little parental care, Type III survivorship curve
• Exponential growth


  Characteristic of populations without limiting factors, such as when introduced to a new environment or rebounding from a catastrophe
• Logistic growth


  Occurs due to limited resources, with K representing the carrying capacity (maximum population size the environment can support)
• Symbiosis


  Interaction between two organisms living in close association