The Nature of Ecology

1
The Nature of Ecology
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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 offspring.
• 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

3
Populations

• 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

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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

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Ecosystem Concepts and Components

• Biomes-areas with a consistent climate and with
  similar organisms
• Climate- long-term weather patterns in a given
  area
• Aquatic life zones- marine and freshwater
  portions of the biosphere

Fig. 4-9 p. 70
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Community Structure and Species Diversity
Fig. 8-2 p. 144
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Biodiversity dependent on latitude
Fig. 8-3 p. 145
Fig. 8-2 p. 144
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Ecosystem Boundaries Ecotones

• Ecotone- transitional zones between ecosystems
  where there are a mixture of species not found
  together in adjacent ecosystems

Fig. 4-10 p. 71
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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.

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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

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Figure 4-13 Page 73
Abiotic Factors That Impact Populations
Aquatic Life Zones
Terrestrial Ecosystems
Sunlight Temperature Precipitation Wind
Latitude Altitude Fire frequency Soil
Light penetration Water currents Dissolved
nutrient concentrations (especially N and P)
Suspended solids Salinity
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The Biotic Components of Ecosystems
Producers (autotrophs) Consumers
(heterotrophs) Decomposers
Fig. 4-16 p. 75
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Food Chains
Fig. 4-18 p. 77 Refer to Fig. 4-19 p. 78
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Food Webs
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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
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Non-native (invasive species)
Species introduced by humans, by mistake or
intentionally. Also called exotic species.
17
http//www.wlf.state.la.us/experience/nutriacontro
l/
18

• Kudzu - aka foot a night vine, mile a minute
  vine, or the vine that ate the south!
• Ironically introduced for soil conservation
  purposes!
• 500 million per year in lost crops and control
  costs

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Special Roles of Some Species
Removal of keystone species will cause collapse
of ecosystem
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Special Roles of Some Species
Keystone Species Pollinators
Top Predators
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Special Role of Some Species
Indicator species - ecosystem smoke alarms -
abundance of population indicator of overall
health and viability of ecosystem
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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-evolution)
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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
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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