Download Concept #: 52.2 Concept Name: Interactions between organisms

Concept #: 52.2
Name:
Concept Name: Interactions between
organisms and the environment limit the
distribution of species.
Essential Question: How do other organisms and the environment limit the distribution of
species?
Questions:
Notes:
Biogeography – the past and present distribution of species
The distribution of organisms produces global and regional
patterns.
Biogeography questions:
-Where do species occur?
-Why do species occur where they do?
-What factors determine their distribution?
Factors:
Biotic – living factors
-all the organisms that are part of the individual’s environment
Abiotic – nonliving factors
-all the chemical and physical factors
Example: temperature, light, water, nutrients
Figure 52.5 (page 1151)
Red Kangaroos occur in the interior of Australia and avoid costal
regions as indicated by the density map.
This distribution suggests an abiotic factor is causing the pattern
but further study would be needed to confirm the results.
Figure 52.6 (page 1152)
Questions to ask when determining limits to a specie’s
distribution:
-Does dispersal limit its distribution?
-Does behavior limit distribution?
-Do biotic factors limit distribution?
-Do abiotic factors limit distribution?
Dispersal – the moment of organisms away from their origin or
form centers of high population density
Critical to understanding both geographic isolation (evolution) and
broad patterns of current geographic distribution of species
Natural range expansions – when a species colonizes a new area
without human influence
e.g. the cattle egret migrated form Africa to the Americas
demonstrate a species ability to disperse affects its distribution
Species transplant – the accidental or intentional movement of a
species to a new area under human influence
Successful transplant means organism survive AND reproduce in
their new area
Potential range – all the areas and environments where a species
could live
Actual range – all the areas and environments where a species
actually lives
Species introduced to a new area often disrupt the ecosystem they
colonized
If a species actual rang < potential range, the organisms
distribution may be limited by habitat selection behavior
Habitat selection behavior is one of the least understood
ecological processes
Species often can not complete their full life cycle as a result of
the actions of other organisms
Organisms that can eat limit the distribution of organisms that can
be eaten.
Figure 52.8 (p1153)
Question: Does feeding by sea urchins limit sea weed distribution?
Experiment: “removal and addition” experiment: Dr. Fletcher
removed urchins, limpets (another herbivore), or both and
observed where sea weeds were most abundant.
Results: sea weeds grew best with neither herbivore was present, a
dramatic increase occurred when only sea urchins were removed.
There were almost no sea weeds in the plots where only limpet
were removed, and the control plot
Conclusion: Sea urchins have the greatest impact on the
distribution of sea weed
Abiotic or physical factors can limit species distribution because
species will not be able to survive and reproduce.
Spatial heterogeneity – environments will vary over distance
Temporal heterogeneity – environments will vary over time
e.g. changes in seasons
these differences may combine to blur or accentuate differences
between environments
organisms can avoid stressful conditions temporarily through
behaviors
e.g. dormancy or hibernation; migration
Temperature: affects the ability of organisms to maintain
biological processes (i.e. metabolism)
-most organisms function best within specific ranges of
temperatures 0°C to 45°C
Water: ability to obtain water affects distribution and evolved
traits of organisms
Salinity: maintaining a salt balance affects the ability of an
organism to regulate itself through osmosis
Sunlight: Plants need light for photosynthesis but too much light
damages DNA and proteins and can increase temperature stresses
Rocks and soil: pH, mineral composition, and physical structure of
rocks and soil limit the distribution of plants, which limits the
distribution of herbivores; in marine environments substrate
determines what kinds of animals can attach to and grown on a
surface
Climate - the long-term prevailing weather conditions in a
particular area
-4 major components:
>temperature
>precipitation
>sunlight
>wind
Macroclimate – patterns on the global, regional, and local level
Microclimate – very fine climate patterns
e.g. the climate encountered by organisms that live beneath a
fallen log
Global climate patters are largely determined by solar energy
input and the planet’s movement through space.
The sun’s warming effect establishes temperature variations, cycle
of air movement, and evaporation of water
Figure 52.10 (pages 1156 – 1157)
-The earth’s curved shape causes latitudinal variation in the
intensity of sunlight. The tropics receive more heat and light per
unit area than higher latitudes
-The Earth’s tilt (23.5° relative to the plane of orbit around the
sun) contributes to the seasons. The seasonal variations in the
tropics are limited and increase toward the poles
-Solar radiation creates air circulation patterns (Hadley, Ferrell,
and Polar cells) which move heat and moisture through the
atmosphere.
-Air flow creates predictable wind patterns. The rotation of the
Earth causes a deflection of the wind
Proximity to bodies of water (i.e. oceans) and topographical
features (i.e. mountain ranges) create regional and local variations
in climate
Figure 52.11 (pages 1155)
The great ocean conveyor belt is the result of unequal heating of
the earth’s surface and distributes heat through out the biosphere
Figure 52.12 (page 1158)
The high specific heat (amount of energy needed to raise the
temperature of a substance by 1°C) of water causes oceans and
lakes to moderate the climate of a given area
Mountains affect the amount of sunlight reaching an area and
contribute to regional climate variations
e.g. south facing slopes receive more sunlight and are warmer
and drier than north facing slopes
These climate variations can influence the species distribution of
different regions
Figure 52.3 (page 1158)
Mountains force air pockets to drop rain on the windward side and
cause deserts to form on the leeward side
e.g. Mojave desert, California
Seasons are marked by changes in day length, solar radiation,
temperature, the changing angle of the sun over the course of the
year.
Seasonal changes often come with changes in wind and
precipitation patterns.
The presence of microclimates increases the presence of smallscale differences which affects the distribution of species.
Past responses of organisms to climate change (i.e. the warming
after the last ice age) can offer clues as to how environments
respond to future climate change.
Past warming caused tree populations to “migrate” north leading
to a prediction that a similar even will occur as the earth’s
temperature continues to rise, Figure 52.14 (page 1159)
Summary: