Download Lecture - Chapter 2 and 3 - Abiotic Factors in Ecology

What is ecology?
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“Ecology works at characterizing the patterns
seen in nature, studying the complex interactions
among organisms and their environments, and
understanding the mechanisms involved in
biological diversity.”
1. Characterizing the patterns
seen in nature
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Example: The River Continuum
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Many differences are seen between the upstream and
downstream stretches of a river
„ Different types of invertebrates
„ Different species of fish
2. Studying complex interactions between
organisms and their environment
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Example: What causes the differences seen
between upstream and downstream sites?
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Possibilities???
3. Understanding the mechanisms
involved in biodiversity
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Why do some reaches of a river tend to have
greater diversity than others? Why do some
rivers have greater diversity than others?
Why do tropical rain forests and coral reefs
have relatively high species diversity compared
to other ecosystems?
The absolute geographical boundaries of
a species are set by abiotic factors
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Global scale: Adelie penguins
would overheat in the tropics
The absolute geographical boundaries of
a species are set by abiotic factors
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Local scale: Giant, green anemones are found in
pooling water in the intertidal, but not on vertical rock
faces
Within limits set by abiotic factors,
biological interactions affect the presence &
abundance of species
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What are some of these biological interactions?
Why are there no polar bears in
the Antarctic?
Shelford’s law of tolerance
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What do the axes mean? What do different
parts of the curve tell us about the species?
Winter distribution of the Eastern phoebe:
Blue line: -4º isotherm, minimum average temp. January
Blue patches: Deviation of phoebe distribution from -4º isotherm.
Seasonal or geographical shifts in
tolerance
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What do the three different curves represent? (>1
possibility)
What does the arrow represent?
What types of values belong on the x-axis?
How might natural selection affect a
species’ tolerance curve?
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Within a single generation?
After several generations?
Global Climate
Change and Species
Shifts
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Example: malaria
Diagram from Bellarmine
University website
Biomes as related to Temperature and
Moisture
Global Distribution of Terrestrial Biomes
What causes the poles to be colder than
equatorial regions?
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Key reason: Curvature of the earth and resultant
angle of sun’s rays [Fig. 2.7a]
Which other factors mediate the distribution
of global temperature?
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Earth’s rotation Æ air and ocean currents that
affect the distribution of heat energy
Earth’s tilt (angle of axis) (Precession)
Albedo (Reflectivity)
Movement of air masses
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If the earth had
no rotation:
Movement of air masses
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With rotation:
Ocean circulation patterns and
heat distribution
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Example: Effect of the Gulf Stream on temperatures (E.
North America; W. Europe)
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The angle of the earth’s axis is responsible for
seasonal variations on the earth.
Fig. 50.12
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
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Position shifts between summer and
winter (why?)
Albedo: reflectance of
solar radiation
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Snow and Ice: high albedo
(Photo: K. Haberman)
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Forested areas: low
albedo
Photo: Natl. Park Svc.
Global patterns of precipitation
Global patterns of precipitation
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Warm air holds more moisture than cold air
Warm air rises and cools, dropping moisture close to where it was picked
up, so moist areas tend to remain moist, and dry areas tend to remain dry
Warm, dry air picks up additional moisture…
Altitude and Rain shadows
North vs. south facing slopes
North vs. south facing slopes (cont.)
Microclimate example: Effects of
vegetation on temperature
Nutrients
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Macronutrients
Definition?
„ Examples: C, H, N, O, P, Ca, Mg, K, S, Na, Cl
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Micronutrients
Definition?
„ Examples: Fe, Mn, B, Co, Cu, Mo, Zn, I, Se
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Global distribution of productivity in the
ocean
Upwelling
Focus on light
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Characteristics that vary with
climate/microclimate
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wavelength
intensity
duration
directionality
Light energy as a function of
latitude and time of year
PAR: Photosynthetically active
radiation (400-740 nm)
Attenuation of light through
water
Attenuation of light through
vegetation
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Leaf area
index
Attenuation of light through
vegetation (cont.)
Other key factors
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Salinity
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Oxygen concentration
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Example: Different estuarine species are tolerant to
different conditions
Example 1: Surface waters vs. sediments in an
estuary
pH
Substrate (i.e. soil type, rocky vs. muddy river
bottom, etc…)
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Example: Distribution of macroinvertebrates in
streams.