An Introduction to Ecology and the Biosphere

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An Introduction to Ecology and the Biosphere

• Chapter 50

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Ecology
The branch of biology that concerns interactions
between organisms and their environments
Ecology is not the same as environmentalism
Environmentalism
Having concern for, or acting in favor of, the
environment
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Levels of Biological Organization
Biomolecule
Organelle
Cell
Tissue
Organ
Organ System
Organism
Population
Within the purview of ecology
Community
Ecosystem
Biosphere
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Ecology
Two principal pattern-based questions are
Where do organisms live?
How common or rare are they?
Ecologists then try to figure out why, by asking
mechanistic questions
E.g.
What factors determine the distribution of a
species?
What factors determine the abundance of a species?
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Ecology
Examples of ecological patterns global
distribution and abundance E.g., red kangaroo
Fig. 50.2
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Ecology
Distribution patterns may be characterized at a
variety of spatial scales
E.g., Tetraphis moss
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Ecology
Range sizes
Few species are widespread (and common) most
species have small ranges (and are rare)
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Dominance-diversity curve for a 50-ha forest
plot in Panama
100000
10000
1000
N
100
10
1
50
100
150
200
250
300
1
Relative abundance ranks of 300 species of trees
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Ecology
The environment of an organism includes
bothabiotic and biotic components
Abiotic components nonliving chemical and
physical properties of an individuals
environment (e.g., temperature, light, water,
nutrient availability, etc.)
Biotic components all of the organisms that are
part of an individuals environment (e.g.,
predators, prey, competitors, mutualists)
Both abiotic and biotic factors may influence the
distribution and abundance of a given species
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Ecology
Consider this example abundance of seaweed
near Sydney, Australia
Abiotic factors dictate that the abundance on dry
land is 0 (not shown in the figure)
Fig.50.8
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Ecology
Consider this example abundance of seaweed
near Sydney, Australia
Herbivore-removal experiments supported the
hypothesis that in the intertidal zone sea
urchins are the main biotic factors that limit
the seaweeds abundance
Fig.50.8
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Ecology
Historical factors may also contribute to the
current distribution and abundance of a given
species
For example, there do not appear to be abiotic or
biotic factors that would keep African honey bees
out of Brazil, yet there were no African honey
bees in Brazil before 1950
See also Fig. 50.7
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Ecology
In 1950 why were there no African honey bees in
Brazil?
1. None had ever naturally dispersed to the
Americas from Africa
2. None had ever been introduced to the Americas
by humans
See also Fig. 50.7
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Ecology
Flowchart of factors limiting geographic
distribution
Fig. 50.6
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Ecology
Flowchart of factors limiting geographic
distribution
Fig. 50.6
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Ecology
Flowchart of factors limiting geographic
distribution
Fig. 50.6
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Ecology
Flowchart of factors limiting geographic
distribution
Fig. 50.6
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Biogeography
Biogeographic realms or provinces delineate
continental-scale regions that are relatively
isolated from one another
Fig. 50.5
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Biogeography
Isolation has important consequences for
evolution, so biogeographic realms encompass
areas with broadly similar evolutionary histories
Fig. 50.5
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Fig. 26.20
Macroevolution Phylogeny
Continental drift is responsible for many
biogeographic distribution patterns
E.g., Proteaceae a plant family that originated
in Gondwana
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Fig. 26.20
Macroevolution Phylogeny
Continental drift is responsible for many
biogeographic distribution patterns
E.g., Marsupials originated on the supercontinent
that became Australia, Antarctica, S.
America
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Global Climate Patterns
Regions of the globe can also be characterized
by their abiotic conditions (e.g., climate)
Fig. 50.18
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Global Climate Patterns
Climate broadly determines the traits of
organisms found in a given location
Fig. 50.18
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Global Climate Patterns
This climograph identifies major kinds of
ecosystems (known as biomes) in North America
Fig. 50.18
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Global Climate Patterns
The tropics are warm the poles are cold
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Global Climate Patterns
The tropics are generally the wettest, latitudes
around 30 are generally the driest, latitudes
around 60 are wet, and polar latitudes are dry
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Global Climate Patterns
See Fig. 50.10
Three main physical attributes of the Earth
determine global climate patterns
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Global Climate Patterns
See Fig. 50.10
1. Shape of the Earth causes unequal heating
(energy per area) with latitude
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Global Climate Patterns
See Fig. 50.10
1. Shape of the Earth differential heating and
cooling causes rising and sinking air masses
Hadley cells
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Global Climate Patterns
See Fig. 50.10
1. Shape of the Earth differential heating and
cooling causes rising and sinking air masses
Hadley cells
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Global Climate Patterns
See Fig. 50.10
2. Revolution of the Earth on a tilted axis
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Global Climate Patterns
See Fig. 50.10
2. Revolution of the Earth on a tilted axis,
which causes Hadley cells to change latitude with
the seasons
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Global Climate Patterns
See Fig. 50.10
2. Revolution of the Earth on a tilted axis,
which causes Hadley cells to change latitude with
the seasons
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Global Climate Patterns
2. Revolution of the Earth on a tilted axis,
which causes Hadley cells to change latitude with
the seasons
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Global Climate Patterns
2. Revolution of the Earth on a tilted axis,
which causes Hadley cells to change latitude with
the seasons
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Global Climate Patterns
3. Rotation of the Earth about its axis
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Global Climate Patterns
See Fig. 50.10
Currents are deflected to the right in the
Northern Hemisphere
Currents are deflected to the left in the
Southern Hemisphere
3. Rotation of the Earth about its axis, which
results in characteristic air and water currents
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Global Climate Patterns
See Fig. 50.10
Currents are deflected to the right in the
Northern Hemisphere
Currents are deflected to the left in the
Southern Hemisphere
3. Rotation of the Earth about its axis, which
results in characteristic air and water currents
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Local Abiotic Conditions
Local factors, such as topography, proximity to
water bodies, and etc., superimpose their effects
on the climate of a terrestrial region to produce
local abiotic conditions (e.g., weather)
Fig. 50.12
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Aquatic Biomes
Occupy the largest proportion of Earths surface
Fig. 50.15
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Aquatic Biomes
Freshwater (lt 1 salt) and marine ( 3 salt)
Fig. 50.15
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Aquatic Biomes
Freshwater Lakes Rivers
Fig. 50.15
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Aquatic Biomes
Freshwater Lakes (standing water)
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Aquatic Biomes
Freshwater Lakes (standing water)
Lake Zonation
Photic zone sufficient light penetrates for
photosynthesis
Fig. 50.16a
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Aquatic Biomes
Freshwater Lakes (standing water)
Lake Zonation
Aphotic zone insufficient light penetrates for
photosynthesis
Fig. 50.16a
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Aquatic Biomes
Freshwater Lakes (standing water)
Lake Zonation
Benthic zone the substrate
Fig. 50.16a
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Aquatic Biomes
Freshwater Lakes (standing water)
Lake Zonation
Littoral zone shallow, well-lit waters close
to shore
Fig. 50.16a
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Aquatic Biomes
Freshwater Lakes (standing water)
Lake Zonation
Limnetic zone well-lit surface waters farther
from shore
Fig. 50.16a
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Aquatic Biomes
Freshwater Rivers (flowing water)
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Aquatic Biomes
Wetlands (marshes, swamps, bogs, etc.)
Areas covered for at least part of the year by
water, and that support aquatic plants
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Aquatic Biomes
Estuaries
Fig. 50.15
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Aquatic Biomes
Estuaries (e.g., Sabine, Atchafalaya,
Mississippi, Pearl)
The area where a freshwater river merges with the
ocean often bordered by wetlands (mudflats and
salt marshes)
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Aquatic Biomes
Marine biomes account for 75 of Earths surface
Fig. 50.15
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Aquatic Biomes
Marine zonation Intertidal zone where land
meets sea from highest high-tide mark to lowest
low-tide mark
Fig. 50.16b
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Aquatic Biomes
Marine zonation Neritic zone shallow regions
over the continental shelves
Fig. 50.16b
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Aquatic Biomes
Marine zonation Oceanic zone regions beyond
the continental shelves
Fig. 50.16b
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Aquatic Biomes
Marine zonation Pelagic zone open water of
any depth
Fig. 50.16b
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Aquatic Biomes
Marine zonation Abyssal zone the deepest
benthos
Fig. 50.16b
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Aquatic Biomes
Marine biomes Intertidal, coral reef, oceanic
pelagic, benthic abyssal
Fig. 50.15
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Aquatic Biomes
Marine Biome Intertidal zones
Alternately submerged and exposed by twice-daily
cycle of tides
The vertical zonation of organisms is common
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Aquatic Biomes
Marine Biome Coral reefs
Warm, tropical waters near continents or islands
(neritic zone) often support coral reefs (built
by the cnidarians that give this biome its name)
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Aquatic Biomes
Marine Biome Oceanic Pelagic
Open ocean waters usually have lower nutrient
concentrations than neritic waters, that
phytoplankton at the base of the food chain
nevertheless exploit
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Aquatic Biomes
Marine Benthic abyssal
Abyssal organisms are generally few and far
between, except where nutrient concentrations are
high, e.g., whale carcasses (ephemeral) and
hydrothermal vents (more permanent)
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Terrestrial Biomes
Fig. 50.19
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Terrestrial Biomes
Warm, wet conditions correspond to high
productivity, whereas cold or dry conditions
result in low productivity
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Terrestrial Biomes
Tropical forest
Fig. 50.19
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Terrestrial Biomes
Tropical forest
Tropical forests account for 7 of the Earths
terrestrial surface area
Even so, gt90 of Earths species may inhabit
tropical forests
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Terrestrial Biomes
Savanna
Fig. 50.19
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Terrestrial Biomes
Savanna
Both tropical...
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Terrestrial Biomes
Savanna
and temperate
Rainfall is insufficient to support closed-canopy
forest, and fire is often a characteristic agent
of natural disturbance
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Terrestrial Biomes
Desert
Fig. 50.19
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Terrestrial Biomes
Desert
Arid conditions generally prevent high
productivity
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Terrestrial Biomes
Chaparral
Fig. 50.19
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Terrestrial Biomes
Chaparral
Midlatitudinal coastal areas with mild, rainy
winters and long, hot, dry summers
Vegetation is dominated by shrubs and small trees
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Terrestrial Biomes
Temperate grassland
Fig. 50.19
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Terrestrial Biomes
Temperate grassland
The key to the persistence of grasslands is
seasonal drought, occasional fires, and grazing
by large ungulates
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Terrestrial Biomes
Temperate broadleaf (deciduous) forest
Fig. 50.19
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Terrestrial Biomes
Temperate broadleaf (deciduous) forest
Temperate broadleaf forests are found at
midlatitudes where there is sufficient rainfall
to support dense stands of trees
Temperate broadleaf trees lose their leaves in
winter
Most temperate broadleaf forests in North America
are secondary (regrowth) forests that returned
after logging in the 19th and 20th centuries
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Terrestrial Biomes
Coniferous forest
Fig. 50.19
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Terrestrial Biomes
Coniferous forest
Large expanses of evergreen, coniferous forests
are found at high latitudes where winters are
cold and long
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Terrestrial Biomes
Tundra (both arctic alpine)
Fig. 50.19
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Terrestrial Biomes
Tundra (both arctic alpine)
Permafrost (permanently frozen subsoil), cold
temperatures, and high winds exclude most tall
plants