Ecology 1: Ecosystems

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Ecology 1 Ecosystems
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Levels of Organization

• Organism
• Ex. an elephant
• Population
• A group of individuals in the same species,
  living and interacting in one area
• Ex. a herd of elephants in the Serengeti
• Community
• Multiple populations interacting in one area
• Ex. grazing antelope, elephants and giraffes in
  the Serengeti
• Ecosystem
• All populations in one area interacting with
  each other and their non-living environment.
• Ex. the Serengeti (all organisms plus climate,
  nutrients, etc.)

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Levels of Organization

• Biosphere
• All areas of the earth from the ocean depths to
  the atmosphere that support life.

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Ecological roles

• Autotrophs - Producer
• makes own food (through photosynthesis or
  chemosynthesis)
• Heterotrophs - Consumer
• must eat other organisms for food
• primary (mouse), secondary (fox), tertiary
  (bobcat)
• Herbivore (eats plants) Carnivore (eats meat)
  Omnivore (eats both)
• Detritivore
• Organisms that feed on animals remains and dead
  material (crabs, earthworms)
• Decomposer
• An organism (ex. fungi or bacteria) that
  completes the final breakdown of materials in an
  ecosystem
• End of 3.1

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How does energy enter the ecosystem?

• Energy hits the earth in the form of sunlight
• Autotrophs convert sunlight (or chemical) energy
  into organic molecules
• Less than 1 of the suns energy is converted
  into organic material
• Eventually all energy is lost back to the
  atmosphere as heat.

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How does energy move through an ecosystem?

• Energy trapped in autotrophs (producers) then
  gets transferred to heterotrophs (consumers) as
  one organism eats another
• The easiest way to show this is by using a food
  chain, food web, or food pyramid.
• Food chain series of steps in which organisms
  transfer energy by eating and being eaten.

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Food Weblinks all ecosystems in a food chain
together
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Food Pyramids

• A food pyramid is designed to show the organisms
  in an ecosystem, grouped by their feeding
  position or trophic level (1stprod,
  2ndherbivores, etc)
• Both food chains and food pyramids show that only
  10 of the energy at one trophic level makes it
  to the next trophic level (from the 2nd law of
  thermodynamics).

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Primary Productivity

• The rate at which new organic material is created
  in an ecosystem by producers is called the
  Primary Productivity
• The more energy entering the food chain (from
  producers), the more that can pass up through the
  levels (only 10 moves up at each level), and as
  result, the more levels there can be.

• Therefore, the ecosystems with the most
  productive producers have the most levels (ex.
  rain forest)
• In most cases, there are only 3-4 levels.
• End of 3.2

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How do nutrients cycle?

• Energy follows a ONE-WAY path
• Sun? living organisms? heat? atmosphere
• Matter CYCLES through living organisms endlessly
• Biogeochemical cycles
• Water
• Carbon and Oxygen
• Nitrogen

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Water Cycle
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Carbon and Oxygen Cycle
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Nitrogen Cycle
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Niches

• Niches vs Habitats
• A habitat is the location where a species lives.
• Ex. tall grassland/prairie
• A niche includes all of the species requirements
  plus its role in the ecosystem. It is determined
  by all the the abiotic and biotic factors
  relevant to the species.
• Ex. Top predator in prairie areas where gophers
  live, and the temperature is never below
  freezing.

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Niche differences

• Organisms can be identified as either
• Generalists
• Organisms with a broad niche
• Eat lots of types of food
• Live in many types of environments
• Ex. house mice
• Specialists
• Organisms with a narrow niche
• Eat a narrow range of food items
• Live in few, specific types of habitats
• Ex. panda bear

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Mutualism

• Mutualism occurs when both species benefit
• Rhinos and oxpeckers
• trees and mycorrhizae,
• ants and acacia
• Termites and protist
• Pollination (Yucca and yucca moth)

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Parasitism

• one organism feeds on/lives on another species
• typically host is bigger than parasite
• parasites usually do not kill host (weaken them)
• parasites need host for food, shelter, etc.
• ex. fleas on dog, tapeworm in human, mistletoe,
  lamprey

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Commensalism

• Commensalism occurs when one species benefits,
  and the other neither benefits, or is harmed
• examples
• clownfish and anemones
• epiphytes and trees
• Cattle egrets and ungulates

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Predation

• Predation - one organism feeds upon the other
• predator usually bigger than prey
• ex. lion eating zebra

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Prey Strategies
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Competition

• When two species use the same resources, they are
  said to compete and their interaction
  competition.
• ex. lions and hyenas compete for food in Africa
• Competition does not necessarily involve contact
  interaction may be only by means of effects on
  the resources.
• No two organisms can occupy exactly the same
  niche at the same time

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What determines where species can live?

• All species have requirements for many
  factors/conditions.
• Abiotic factors non-living factors ex.
  temperature, precipitation, pH
• Biotic factors other species ex. prey species,
  competing species
• For each of these factors, species exhibit a
  range of tolerance.
• For example, a fish species may only be found
  within a pH range of 4.5 to 6 in lakes.

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Biomes

• A major terrestrial community that is found in
  different areas with similar climate is called a
  biome. A biomes structure and appearance are
  similar throughout its distribution.
• The worlds biomes are tropical rain forest,
  tropical dry forest, temperate woodland and
  shrubland (Chaparral), temperate deciduous
  forest, boreal/coniferous forest (taiga), desert,
  temperate grassland, tropical grassland
  (savanna), and tundra.

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Biome distribution
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Freshwater Habitats

• These habitats are distinct from both marine and
  terrestrial habitats and are very limited in
  area.
• make up about 2 of earths surface
• can be divided into
• Flowing water (rivers) standing water (ponds and
  lakes) and wetlands (seasonal coverage)

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Freshwater Habitats

• Estuaries
• These are very important for
• Breeding grounds for fish
• Filtering water
• Very productive ecosystems!
• Disappearing fast (flat land near the ocean)

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Ocean

• 75 of earths surface
• Continental shelf - shallow ocean waters -
  smallest area large number of species (kelp
  forests)
• Intertidal zones
• Along our coast
• Species can tolerate being in and out of water
• Sea stars, algae, sea anemones
• Coral Reefs
• The rain forests of the ocean
• High diversity
• In tropical waters

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Ocean

• open sea surface - contains plankton
  (free-floating microscopic organisms), bacteria,
  algae, fish larvae responsible for 40 of
  worlds photosynthesis
• Benthic zone - deep sea waters - below 1000 feet
  animals adapted to dark some blind/bioluminescent

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What happens when ecosystems are disturbed?

• When a disturbance impacts an ecosystem, it
  recovers through a process known as succession.
• Succession on newly formed habitat is called
  primary succession.
• No remaining organisms or soil
• Examples, lava flow, sand dune, glacier retreat
• It can take 1000 years from sand dune to forest.