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Ecology 1: Ecosystems

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Title: Ecology 1: Ecosystems


1
Ecology 1 Ecosystems
2
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.)

3
Levels of Organization
  • Biosphere
  • All areas of the earth from the ocean depths to
    the atmosphere that support life.

4
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

5
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.

6
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.

7
Food Weblinks all ecosystems in a food chain
together
8
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).

9
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

10
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

11
Water Cycle
12
Carbon and Oxygen Cycle
13
Nitrogen Cycle
14
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.

15
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

16
Mutualism
  • Mutualism occurs when both species benefit
  • Rhinos and oxpeckers
  • trees and mycorrhizae,
  • ants and acacia
  • Termites and protist
  • Pollination (Yucca and yucca moth)

17
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

18
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

19
Predation
  • Predation - one organism feeds upon the other
  • predator usually bigger than prey
  • ex. lion eating zebra

20
Prey Strategies
21
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

22
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.

23
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.

24
Biome distribution
25
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)

26
Freshwater Habitats
  • Estuaries
  • These are very important for
  • Breeding grounds for fish
  • Filtering water
  • Very productive ecosystems!
  • Disappearing fast (flat land near the ocean)

27
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

28
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

29
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.
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