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Chapter Three
Ecology: the study of systems that include interactions among organisms and
between organisms and their abiotic environment
-Ernst Haeckel, 19th century
Eco= house, logy= study à the study of “one’s house”
Biotic: living environment; all organisms
Abiotic: nonliving surroundings; living space, temperature, soil, wind
Humans are biological organisms
Species: a group of similar organisms whose members freely interbreed with one
another in the wild to produce fertile offspring; members of one species generally
do not interbreed with other species of organisms
Population: a group of organisms of the same species that live in the same area at
the same time
Community: a natural association that consists of all the populations of different
species that live and interact within an area at the same time
-Feeding relationships
Ecosystem: a community and its physical environment
-All biotic interactions of a community
-Terrestrial, aquatic
-Biological, physical, chemical components= complex
Landscape Ecology
Landscape: a region that includes several interacting ecosystems
-Forest ecosystem near pond ecosystems
Biosphere: parts of Earth’s atmosphere, ocean, land surface, and soil that contain all
living organisms
-Atmosphere= gas surrounding Earth
-Hydrosphere= supply of water
-Lithosphere= soil, rock of Earth’s crust
ENERGY
Chemical, radiant, thermal, mechanical, nuclear, electrical, potential energy, kinetic
energy
Thermodynamics: the study of energy and its transformations
~First law: energy cannot be created nor destroyed, although it can change from
one form to another~
-Organisms may absorb energy from its surroundings
-Cannot create the energy it requires, needs to capture it

ex: Photosynthesis
~Second law: when energy is converted from one form to another, some of it is
degraded into heat and is less usable~

Also called “Entropy”
-Entropy in a system increases over time
-No process requiring energy conversion is ever 100% efficient

ex: Gasoline in a car
Photosynthesis: the biological process in which light energy from the sun is
captured and transformed into the chemical energy of sugar molecules

6CO2+12H2O+ radiant energy àC6H12O6+6H2O+6O2

Cellular Respiration: the chemical that plants store in carbs is released within cells
of plants, animals, or other organisms

C6H12O6+6O2+6H2O à 6CO2+12H2O+ energy
Energy flow: passage of energy in a one-way direction through an ecosystem
-All organisms respire to obtain some energy
PRODUCERS, CONSUMERS, DECOMPOSERS
Producers= autotrophs
Consumers= animals, heterotrophs

Primary consumers= consumers that eat producers

Secondary consumers= eat primary consumers

Tertiary consumers= eat secondary consumers
Detritus feeders= snails, worms
Decomposers= saprotrophs, break down dead organic material
Trophic level: an organism’s position in a food chain, which is determined by its
feeding relationships
Producers 1st, Primary Consumers 2nd, Secondary Consumers 3rd, etc
...
High reproductive capacity’
2
...
Limits on population growth, struggle for existence
4
...
animals = old perspective
Microscopes à understanding that bacteria doesn’t fit into a plant/animal kingdom
Archea
-Oxygen deficient environments (ex: Old Faithful in Yellowstone, hydrothermal
vents)
Bacteria
-Remaining prokaryotes = bacteria
*Eukarya
-Plants, animals, protists, fungi
-High degree of internal organization (nuclei, chloroplasts, mitochondria)
-Four Kingdoms

1
...
Fungi

3
...
Animalia
Population Ecology
Population: a group of individuals of the same species that live in the same
geographic area at the same time
Population characteristics
-Population density, birth/death rates, growth rates, age structure
àPopulation ecology= deals with numbers of species found in an area over time

-Food, predation, disease, environmental pressure
Population density: number of individuals of a species per unit of area or volume
at a given time
Growth rate: the rate of change of a population’s size, expressed in percent per year
à R= B-D
R= growth rate
B= birth rate (# of births per 1000 per year)
D= death rate (# of deaths per 1000 per year)
Intrinsic rate of increase: exponential growth of a population that occurs when
resources are not limited (biotic potential)
-Factors involved= age of reproduction, life span of reproduction
Exponential population growth: the accelerating population growth that occurs
when optimal conditions allow a constant reproductive rate over a period of time
ENVIRONMENTAL RESISTANCE
-Organisms cannot reproduce indefinitely, there are limits
Negative feedback mechanism à change triggers reverse condition

Ex: extended drought lowers carrying capacity for herbivores to eat grass
Sustainable harvest: number of individuals that can be harvested from a
population each year without reducing the total population

Ex: the number of fish caught each year, pest control


Population Sizes
Density-Dependent vs
...
91)
Density-independent: environmental factor that affects the size of a population but
is not influence by changes in population density
-Typically abiotic

Ex: random weather events
Survivorship, Life Tables


-Shows relationship between age/likelihood of survival
Survivorship: the probability a given individual in a population will survive to a
particular age
Metapopulation: a set of local populations among which individuals are distributed
in distinct habitat patches across a landscape
-Each local population has distinct birth, emigration, and immigration rates
High quality habitats= “source habitat”
Lower-quality habitats= “sink habitat”
BIOLOGICAL COMMUNITIES
Community: an association of different populations of organisms that live, interact
in the same place
-A biological community and its abiotic environment = ecosystem
Ecological niche: the totality of an organism’s adaptations, its use of resources, and
the lifestyle to which it is fitted
-Involves all aspects of the organism
Limiting resource: any environmental resource that restricts the ecological niche
of an organism
Competition: interaction among organisms that vie for the same resources in an
ecosystem (food or living space)
-One of many factors that affects community structure
Competitive exclusion, resource partitioning
Symbiosis: any intimate relationship or association between members of two or
more species
-Mutualism, commensalism, parasitism
Mutualism: a symbiotic relationship in which both partners benefit
Commensalism: one organism benefits and the other is neither harmed nor helped

Ex: social insects and scavengers (silverfish)
Parasitism: one organism benefits, the other is adversely affected

Ex: Ticks
Keystone species: a predator that exerts a profound influence on a community in
excess of that expected by its relative abundance
Community Development

Primary succession: the change in species composition over time in a previously
uninhabited environment
Secondary succession: change in species composition that takes place after some
disturbance destroys the existing vegetation

Chapter Six
EARTH’S MAJOR BIOMES
Earth has many climates based on temperature
Biome: a large, distinct terrestrial region with similar climate, soil, plants, and
animals, regardless of where it occurs in the world
-Encompasses many interacting ecosystems
-Next level of ecological organizations
(Arctic) tundra: the treeless biome in the far north that consists of boggy plains
covered by lichens and small plants; harsh winters and short summers
-Soils are geologically young
-Layer of permafrost, low species richness, low primary production
-Oil, natural gas exploration= long-lasting damage
Boreal forest: a region of coniferous forest in the Northern Hemisphere, just south
of the tundra
-Primary source of industrial wood and wood fiber
Temperate rain forest: a coniferous biome with cool weather, dense fog, high
precipitation
-Mild winters, cool summers
-Douglas Fir
-Stable forest ecosystems= biological habitats
Temperate Deciduous Forest: a forest biome that occurs in temperate areas with a
moderate amount of precipitation
-Hot summers, cold winters
-First biomes converted to agricultural use
Temperate grasslands: grassland with hot summers, cold winters, and less rainfall
than the temperate deciduous forest biome
-Considerable organic material
-Illinois, Iowa, Minnesota, Nebraska
Chaparral: biomes with mild, moist winters and hot, dry summers; vegetation is
typically small leaved evergreen shrubs and small trees
Deserts: a biome in which the lack of precipitation limits plant growth; deserts are
found in both temperate and subtropical regions
-Soil is exposed, Joshua trees, cacti, yucca plants
-Desert animals are small
-Off-road vehicles inflict environmental damage
Savanna: tropical grassland with widely scattered trees or clumps of trees
-Africa, South America, Northern Australia
-Desertification
Tropical rain forest: a lush, species-rich forest biome that occurs where the
climate is warm and moist throughout the year
-Central/South America, Africa, Southeast Asia

-Plants capture energy through photosynthesis
-Species richness, variety
AQUATIC ECOSYSTEMS
Light= limiting factor
Freshwater vs
...
Free-floating plankton
2
...
Bottom-dwelling benthos (oysters, worms, crawfish)
Plankton àPhytoplankton, Zooplankton
FRESHWATER
Flowing water ecosystem: a freshwater ecosystem such as a river, or stream, in
which the water flows in a current
-Pollution from industry, agriculture, cities, lawns ALTER
Standing water ecosystems: a body of fresh water that is surrounded by land and
that does not flow; lake or pond
-Littoral, limnetic, profundal zones
Littoral= shallow water area, most productive
Limnetic= open water, away from shore
Profundal= deepest zone, light doesn’t penetrate effectively
Freshwater wetland: land that shallow fresh water covers for at least part of the
year and that has a characteristic soil, water-tolerant vegetation
-Plants= highly productive, provide food to support organisms
ESTUARIES
Estuary: a coastal body of water, partly surrounded by land, with access to the open
ocean and a large supply of fresh water from a river
-Rise and fall with the tides, salinity fluctuates
1
...
Tidal action promotes rapid circulation of nutrients
3
...
Presence of plants provides an extensive photosynthetic carpet à traps detritus,
forms base of food web
-Usually contains salt marshes
MARINE ECOSYSTEMS
Gravitational pulls of the sun and moon
Drifting buoys
Marine environment subdivided into life zones:
-Intertidal
-Benthic
-Pelagic
Intertidal zone: the area of the shoreline between low and high tides
-Productive habitat, anchorage for seaweed, takes force of hurricanes, typhoons
Benthic environment: the ocean floor, which extends from the intertidal zone to
the deep ocean trenches

-Sand and mud, bacteria is common
Seagrass beds, kelp forests, coral reefs
Pelagic environment: all ocean water, from the shoreline down to the deepest
ocean trenches
-Euphotic zone
Neritic province: part of the pelagic environment that overlies the ocean floor from
the shoreline to a depth of 200m
Oceanic province: overlies the ocean floor at depths greater than 200m
Human impacts on ocean= trash, pollution, pesticides



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