Ecosystem structure

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					The Nature of Ecology
                     The Nature of Ecology
   Ecology- the study of how organisms interact with
    their environment
   Organisms- any life form
       Cells- the basic unit of life; come in two flavors
            Prokaryote- cells with no defined nucleus; bacteria
            Eukaryote- cells with a defined nucleus that contains DNA; most
             familiar organisms and multicellular organisms
   Species- groups of organisms that share similar DNA;
    look similar, have similar behavior, can produce viable
       Asexual Reproduction-cellular division to produce identical
        offspring (clones)
       Sexual Reproduction- production of offspring by combining
        sex cells (gametes) to create progeny that are a combination
        of each of the parents’ characteristics
   Population- all of the
    organisms within a
    species that interact in a
    specific area and at a
    specific time
       Genetic Diversity- similar
        but different due to DNA
       Affected by:
          Size

          Age distribution

          Density

          Genetic composition
Communities, Ecosystems & The Biosphere
   Habitat- the place where a population or organism lives
   Community- all of the organisms that occupy a specific area;
    also called biological community
   Ecosystem- a community of different species and their
    interaction with each other and abiotic factors in environment
Ecosystem Concepts and Components
                         Biomes-areas
                          with a consistent
                          climate and with
                            Climate-
                             patterns in a
                             given area
                         Aquatic life
                          zones- marine
                          and freshwater
                          portions of the
 Fig. 4-9 p. 70           biosphere
Community Structure and Species Diversity

                                  Fig. 8-2 p. 144
Biodiversity dependent on latitude

                                        Fig. 8-3 p. 145

                                     Fig. 8-2 p. 144
Ecosystem Boundaries: Ecotones
                       Ecotone-
                        zones between
                        where there are
                        a mixture of
                        species not
                        found together
                        in adjacent

                          Fig. 4-10 p. 71
Principles of Ecological Factors
   Abiotic Factors- all of the nonliving parts in an ecosystem
   Biotic Factors-all of the living factors in an ecosystem
   Range of Tolerance- any variation in the physical or chemical
    environment that an organism can withstand before it is killed/harmed
      Law of tolerance-the existence, abundance, and distribution of a
       species in an ecosystem are determined by whether the levels of one
       or more physical or chemical factors fall within the range tolerated by
       that species.
Regulating Population Growth
   Limiting Factors- a distinguishing chemical or
    physical factor that regulates the population
    growth of a species; more specific than any
    other factor
       Limiting Factor Principle- Too much or too little of
        any abiotic factor can limit or prevent growth of a
        population, even if all other factors are at or near
        the optimum range of tolerance.
   Niche- an organisms functional role within an
    ecosystem; everything that affects the survival
    and reproduction
       Range of tolerance; resources it utilizes (food,
        space); interaction with other biota and abiotic
        factors; its role in the food web/matter cycle
Abiotic Factors That Impact Populations

 Terrestrial Ecosystems       Aquatic Life Zones

 • Sunlight
                          •Light penetration
 • Temperature
                          • Water currents
 • Precipitation
                          • Dissolved nutrient
 • Wind                    concentrations
 • Latitude                (especially N and P)
 • Altitude               • Suspended solids
 • Fire frequency         • Salinity 4-13 Page
                            Figure                 73
 • Soil
The Biotic Components of Ecosystems



Decomposers          Fig. 4-16 p. 75
Food Chains

     Fig. 4-18 p. 77; Refer to Fig. 4-19 p. 78
Food Webs
Native Species
Species naturally evolved to live in the
area. Ex. douglas fir, western red
cedar, milkvetch, black squirrel

Native (indigenous) - naturally
evolved to live in the area Western Red
Cedar, Douglas Fir, Milkvetch, black squirrel
Non-native (invasive species)
Species introduced by
humans, by mistake or
intentionally. Also
called exotic species.
Kudzu - aka: foot a night vine, mile a
minute vine, or the vine that ate the
Ironically introduced for soil conservation
$500 million per year in lost crops and control
costs                                   QuickTime™ an d a
                              TIFF (Uncompressed) decompressor
                                 are need ed to see this picture.
Special Roles of Some Species

Removal of keystone species will cause
collapse of ecosystem
Special Roles of Some Species

Keystone Species
   Pollinators        Top Predators
Special Role of Some Species
Indicator species - ecosystem smoke alarms - abundance of
population indicator of overall health and viability of
Species Interactions: Competition

Interspecific competition-
competition between two
or more species

As a result of competition,
the two species evolve to
gain separate, more
specialized niches (co-
Species Interactions

Mutualism - benefits both species
Ex. pollination

Commensalism - benefits one species,
but has little effect on the other
Ex. Fern living in the shade of a tree
Species Interactions: Parasitism
Parasite - living on or in another
species (host)

 Important ecological role of parasites-
 increase biodiversity by keeping species that
 may eliminate other species in check

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