Ecology Exam Review
Abiotic
•Temp
•Light
•Water
•Wind
•Nutrients
Factors
influencing pop
structure &
process:
•Extinction
•Distribution
•Growth
Landscape Ecology
The study of the
exchanges of materials,
energy or organisms
among ecosystems
Boreal or Taiga
dominated by black spruce; cold climate;
moist soils)
Arctic tundra
(small plants & no trees, poorly developed
soils
Desert
hot, low soil moisture, sandy soils
Tropical Rain Forest
wet, warm; very biologically diverse
Climate
is defined as the average weather
pattern over a long period of time at a particular
location, normally in terms of temperature and
precipitation.

Toronto’s climate: cold winters, warm summers,
approx. 900 mm of precipitation per year.

Weather
is defined as the meteorological
conditions at a point in time (weather forecast for
today is cloudy, warm, windy, with 30% chance
of precipitation, etc)
What affects distribution of
climate around the earth?
Spherical shape of the earth and tilt of earth’s
axis cause uneven heating of earth’s surface.

Uneven heating drives major global air
circulation patterns and consequently
precipitation and biome distribution patterns.

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Tropical Hadley Cell in northern hemisphere
Circulation pattern in cell caused by:
• Warm, moist air rises.
• Moisture cools, condenses, and falls as
rain.
• Some of the dry ascending air travels
northward. Then cooler, dry air falls back to surface.
Once air has been set in motion, it undergoes an
apparent deflection from its path, as seen by an
observer on the earth. This apparent deflection
is called the “Coriolis force” and is a result of the earth’s rotation or daily spin.–deflected to the right in northern hemisphere and left in southern
Major water (moisture) pools
– Clouds/atmospheric moisture
– Rivers, streams, glaciers
– Groundwater
– Oceans
Controls of aquatic organism distributions
temperature
– salinity
– physical conditions (light, current)
– water chemistry (nutrients, acidity)
Spontaneous generation
an
early hypothesis used to explain
how species arose
Special creation
cannot be
tested (based on faith, not
observation) and therefore
outside the realm of science
Lamarck
inheritance of
acquired characteristics of
individuals
Gregor Mendel
characteristics
pass from parent to offspring in the
form of discrete packages (genes).
Genes come in alternative forms
= alleles
Gregor Mendel
characteristics
pass from parent to offspring in the
form of discrete packages (genes).
Genes come in alternative forms
= alleles
Genotype
genes (DNA) of an
organism for a particular trait or traits,
which may or may not be expressed
Phenotypic
visible
expression of a genotype
Variation
•Variation exists in populations
•Some variation has a genetic basis
& is therefore inheritable
•Variation can be neutral, beneficial
or detrimental
•All genetic variation arises by
chance
Excess offspring
All species have the capacity to
produce more offspring than can
survive to reproduction
Competition
There is competition among
individuals in a population for the
limited resources
Natural Selection
Some individuals will be successful at
obtaining enough resources and
surviving to reproduction & producing
offspring. Others will not.
Allele frequency
Natural selection on phenotypes
results in changes in allele
frequency from generation to
generation.
Changing environment
As the environment changes,
organisms over time adapt to local
environment
Speciation
•The origin of species
•Speciation can be an outcome of
evolution – when a population
changes sufficiently over time
Genetic Drift
Mechanism of evolution due to random changes in the allelic frequencies of a
population
What limits population growth
Density – dependent factors:
•Disease
•Predation
•Competition
•Behavioral
Richness
number of species
Evenness
– relative abundance in a community
Shannon-Wiener Index:
•Index of species diversity
•Takes into account both richness &
evenness
Limits to population growth Density – dependent factors:
•Disease
•Predation
•Competition
•Behavioral
limits to population growth, Independent Factors
•Floods
•Extreme temperatures
Intraspecific competition
competition –
compete with members of own
species (conspecifics)
Interspecific competition
compete with other species
Interference Competition
direct aggressive interaction
between individuals
Exploitative Competition
access
to resources without direct
aggressive interactions (e.g.,
some forms of territoriality)
Competitive Exclusion Principle
States that no two species with
identical ecologies can coexist
Or
• Two species with similar needs
for the same limiting resource
cannot coexist
Fundamental Niche
physical
conditions under which a species
might live in the absence of
interactions of other species
Realized Niche
interactions that may restrict the
environments in which a species
lives
Character Displacement
tendency for characteristics of
two species to be more different in
an area of sympatry than when they
are allopatric

Sympatry – in the same place
• Allopatry – in different regions

BATESIAN MIMICRY
Occurs when one organism which is
harmless (the mimic which does not
taste disgusting or sting) looks like one
that is harmful (the model).
MULLERIAN MIMICRY
Occurs when
several nasty
tasting or
stinging
organisms
evolve to look
like one
another
Symbiosis
close interactions
between species
Commensalism
one species
benefits the other neither
benefits or harmed
Facultative
can live without
partnership
Obligate
Obligate – cannot live in
absence of partnership
Primary Productivity
Primary production: Fixation of
energy by autotrophs in an
ecosystem
Organisms and Landscape
Structure
African elephants knock down tress
– Change woodland to grassland
Kangaroo Rats dig burrow systems
that modify soil structure and plant
distributions
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