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Ecology
Is the scientific study of the interactions between organisms and the environment
These interactions
Determine both the distribution of organisms and their abundance
Where organisms are found and how many of them there are
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Ecology
Both observational/descriptive and experimental
Observing what’s there and seeing how it changes
Rigorous - mathematical modeling of populations and ecosystems
Ecological time
Minute-to-minute interactions
Compare to evolutionary time
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Abiotic factors
non-living chemical & physical factors
Temperature
Light
Water, including salinity
Nutrients, including soil and rocks
Dissolved oxygen!
Biotic factors
living components
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Affect the distribution and abundance of organisms
Kangaroos/km 2
> 20
10 –20
5 –10
1 –5
0.1
–1
< 0.1
Limits of distribution
Climate in northern Australia is hot and wet, with seasonal drought.
Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year.
Southeastern Australia has a wet, cool climate.
Southern Australia has cool, moist winters and warm, dry summers.
Tasmania
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The figure below (Figure 52.5 in the textbook) shows the distribution of red kangaroos in Australia. From this figure, you can predict that kangaroos: a.
b.
c.
d.
e.
eat plants prefer a hot dry climate don’t like saltwater prefer to live in areas where people don’t live are more abundant in some years than in other years
Kangaroos/km 2
> 20
10 –20
5 –10
1 –5
0.1
–1
< 0.1
Limits of distribution
Climate in northern Australia is hot and wet, with seasonal drought.
Southern Australia has cool, moist winters and warm, dry summers.
Tasmania
Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year.
Southeastern Australia has a wet, cool climate.
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Dispersal - the movement of individuals away from their area of origin or from centers of high population density
Natural range expansion
Early humans “out of Africa”
Different from migration
Species transplants
Potential vs. actual ranges
Where organisms could be versus where they are
Invasive/introduced species
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Climate - Long-term prevailing weather in a particular area
Macroclimate - Patterns on a global, regional and local level
Microclimate - Patterns on a smaller scale
Ex. A community living under a log
Lichen Rotting Logs Tide Pools
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Latitudinal variation in sunlight intensity
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Seasonal variation in sunlight intensity
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Global air circulation and precipitation patterns.
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Global wind patterns
Currents and other bodies of water
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Mountains and elevation
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benthos coral reef intertidal
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30
N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30
S
Continental shelf benthos
Key
Lakes
Coral reefs
Rivers
Oceanic pelagic zone intertidal
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Estuaries
Intertidal zone
Abyssal zone
(below oceanic pelagic zone) coral reef
Account for the largest part of the biosphere in terms of area
Can contain fresh (aquatic), brackish, or salt (marine) water
Oceans
Cover about 75% of Earth’s surface
Have an enormous impact on the biosphere
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Are stratified into zones or layers defined by light penetration, temperature, and depth
Thermoclines Intertidal zone - Narrow vertical zone of
Neritic zone Oceanic zone abrupt temperature change. zone
Limnetic zone
0
200 m
Continental shelf
Photic zone
Pelagic zone
Benthic zone
Photic zone
Aphotic zone
Benthic zone
Pelagic zone
Aphotic zone
2,500
–6,000 m
Abyssal zone
(deepest regions of ocean floor)
(a)
Zonation in a lake. Based on light penetration, distance from short and water depth, and open water or bottom.
(b) Marine zonation.
Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones).
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1
Lakes and other marine/aquatic biomes experience turnover
2
In spring, as the sun melts the ice, the surface water warms to 4 °C
In winter, the coldest water in the lake (0 °C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4 –5°C at the bottom.
and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O
2
) to the bottom waters (see graphs) and nutrients to the surface.
Spring O
2
(mg/L)
0 4 8
Winter
0
O
2
(mg/L)
4 8 12 12
8
16
24
4
C
4
4
4
2
0
4
C
4
4
4
4
4
O
2 concentration
High
Medium
Low
8
16
24
8
16
24
O
2
(mg/L)
0 4 8 12
Autumn
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4
4
C
4
4
4
4
O
2
(mg/L)
0 4 8 12
Thermocline
4
C
5
6
8
20
18
22
Summer
8
16
24
3
In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline.
Oligotrophic nutrient poor, oxygen rich
Eutrophic - nutrient rich, oxygen poor
Periodic oxygen depletion; large amount of decomposition
Biota - fish, invertebrates depending on O
2 levels, phyto- and zooplankton
An oligotrophic lake in
Grand Teton, Wyoming
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LAKES
A eutrophic lake in Okavango delta, Botswana
Inundated with water at least periodically
Plants adapted to water-saturated soil
Highly productive
Important filters and breeding grounds
Birds, carnivores, crustaceans, plants, reptiles
WETLANDS
Okefenokee National Wetland Reserve in Georgia
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Current with lots of aeration
Aquatic plants and phytoplankton, fish, invertebrates, etc.
Ex. Potomac and
Anacostia rivers,
Rock and Sligo creeks, Chesapeake
Bay watershed
STREAMS AND RIVERS
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Figure 50.17
A headwater stream in the
Great Smoky Mountains
The Mississippi River far form its headwaters
Transition between rivers and sea - brackish water with flow between the two
Variable salinity depending on temperature, depth, and tides
Worms, oysters, crabs, fish, etc.
Highly productive and important in filtering water
ESTUARIES
Figure 50.17
An estuary in a low coastal plain of Georgia
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Periodically submerged and exposed
Physical environment varies vertically, so species range varies vertically
Oxygen and nutrients renewed tidally
Sea grass, algae, worms, crustaceans, crabs, etc.
INTERTIDAL ZONES
Figure 50.17
Rocky intertidal zone on the Oregon coast
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OCEANIC PELAGIC BIOME
Figure 50.17
Open ocean off the island of Hawaii
Open ocean, particularly deep water
Driven by currents - lots of light and oxygen; large photic zone
Experience nutrient turn over - depends on temperature
70 percent of world’s surface
Phytoplankton and photosynthetic bacteria - makes our oxygen!
Zooplankton, fish, cephalopods, marine mammals, etc.
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Formed from coral
“skeletons”
Photic zone - zooxanthellae need light for
CORAL REEFS photosynthesis; sensitive to change in temperature
Fringing reef --> barrier reef
--> atoll island
Unicellular algae, coral animals, fish and invertebrate diversity
Figure 50.17
A coral reef in the Red Sea
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Below neritic (near,
MARINE BENTHIC ZONE coastal) and pelagic
(noncoastal, open water) zones
Deep benthic = abyssal zone; deep sea vents with chemoautotrophs
Shallow benthic - oxygen from algae and seaweed
Chemo- or photoautotrophs; worms, arthopods, echinoderms, etc.
A deep-sea hydrothermal vent community
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distribution: equatorial precipitation: very wet temperature: always warm characteristics: many plants & animals, thin soil
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distribution: equatorial precipitation: seasonal, dry season/wet season temperature: always warm characteristics: fire-adapted, drought tolerant plants; herbivores; fertile soil
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distribution: 30 °N & S latitude band precipitation: almost temperature: variable daily & seasonally, hot & cold characteristics: sparse vegetation & animals, cacti, succulents, drought tolerant, reptiles, insects, rodents, birds
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distribution: mid-latitudes, mid-continents precipitation: seasonal, dry season/wet season temperature: cold winters/hot summers characteristics: prairie grasses, fire-adapted, drought tolerant plants; many herbivores; deep, fertile soil
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distribution: mid-latitude, northern hemisphere precipitation: adequate, summer rains, winter snow temperature: moderate warm summer/cool winter characteristics: many mammals, insects, birds, etc.; deciduous trees; fertile soils
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distribution: high-latitude, northern hemisphere precipitation: adequate to dry (temperate rain forest on coast) temperature: cool year round
2005-2006
distribution: arctic, high-latitude, northern hemisphere precipitation: dry temperature: cold year round characteristics: permafrost, lichens & mosses, migrating animals
2005-2006
distribution: high elevation at all latitudes precipitation: dry temperature: cold year round characteristics: permafrost, lichens, mosses, grasses; migrating
2005-2006