Reminders:

1
Reminders

• Tomorrow, 10am SHARP! _at_ oakland museum
• Next time Quiz 6 ch. 20, 21, 24, 34
• Last lab next week Heart/Senses
• Last lab exam 5/15 5/17

2
Lecture outline

• Introduction to the biosphere
• Definition of the biosphere
• Environmental problems reveal limits of the
  biosphere
• Physical chemical factors
• Organisms adapt to their environment
• Regional climate influences distribution of
  communities
• Aquatic Biomes
• Saltwater biomes (oceans), freshwater biomes
• Terrestrial Biomes
• Tropical forests, savannas, deserts, chaparral,
  temperate grasslands, temperate forests,
  coniferous forests, tundra

3
Ecology the scientific study of the
interactions of organisms with their environments
Aspects an ecologist might study
Organism
How an organism has become adapted to its
environment
An individual living thing.
An group of individuals of one species living in
a particular area.
What factors might limit the size of a population
Population
Interspecies interactions, such as the effect of
predation by crabs on a worm population
All the populations of different species that
inhabit a particular area.
Community
How changes in temperature, chemicals in the
environment, etc. affect organisms
All the organisms in an area, the nonliving
factors with which they interact.
Ecosystem
Biosphere
All the environments on earth that support life.
Too large-scale to study all at once . . .
4
The biosphere

• The biosphere is the total of all of Earths
  ecosystems.
• The biosphere is patchy.
• On a global scale, the
  distribution of oceans and
  continents is not
  uniform.
• On a regional scale, the
  distribution of deserts,
  grasslands, forests,
  lakes,
  and streams, etc. is not
  uniform.
• Aerial view of an Alaskan
  wilderness area shows
  
  patchiness on a local
  scale.

Figure 34.2A
Figure 34.2B
5
Environmental problems reveal the limits of the
biosphere

• Human activities and technology have had a major
  impact on all parts of the biosphere.
• Widespread use of chemicals has led to air,
  water, and soil pollution, affecting the health
  of humans and many other organisms.
• Increasing numbers of communities are adopting a
  Precautionary Priciple w/regard to
  chemicals--this means that until we know a
  chemical is safe, it is not approved for use in
  the community (until we are sure, err on the side
  of caution).
• Growing numbers of endangered or extinct species
  due to loss of habitat.
• Localized famines aggravated by land misuse and
  expanding population growth.
• Potentially massive changes throughout the
  biosphere due to global warming.

6
Rachel Carson

• Famous ecologist
• Much of our current environmental awareness stems
  from her book, Silent Spring, pub. in 1962.
• Was one of the first people to perceive the
  global dangers of pesticide use.
• She predicted negative impacts of the
  pesticide DDT on ecosystems and
  human health.
• Rachel Carson died in 1964 of
  breast cancer.
• DDT was eventually banned in 1972.
• shown to harm predatory birds
• found in human breast milk
• shown to have cancer-promoting
  activity listed as a probable
  carcinogen

Figure 34.3
7
Physical and chemical (abiotic) factors influence
life in the biosphere

• Solar energy Powers nearly all terrestrial and
  shallow-water ecosystems.
• Has major effect on growth and distribution of
  photosynthetic bacteria and algae in the ocean
• In shaded forests, plants at ground level have to
  compete for light.
• Water Essential for life
• In oceans, adaptations are needed to control
  water/solute balance.
• On land, adaptations are needed to prevent drying
  out.
• Temperature Most animals cant function at
  extreme temperatures
• Some have adaptations to allow life in freezing
  or very hot temperatures.
• Wind
• Wind damage during storms can create openings in
  forests, contributing to patchiness in
  ecosystems.
• Can be cooling, but also increases water loss.

8
Organisms are adapted to abiotic and biotic
factors by natural selection

• EX. in text the pronghorn antelope lives in the
  open plains and shrub deserts of North America.
• Abiotic factors dry, windy envt that is subject
  to extreme temperatures
• thick coat made of hollow hairs that can trap air
  and use it as insulation pronghorn can raise
  patches of hair to release body heat.
• Water isnt a problem b/c pronghorns get water
  from the vegetation they eat.
• Biotic factors
• Teeth adapted for biting and chewing plants
  in their habitat
  (forbs, grasses, shrubs).
• Stomach contains cellulose-digesting
  bacteria to release
  the nutrients to the
  pronghorns system.
• Runs with great speed and endurance to be
  able to escape
  predation by wolves, coyotes,
  and cougars that have overlapping
  habitats.
• Have tan and white coat that helps camouflage
  them.
• Live in herds for protection

Figure 34.5
9
Regional climate influences the distribution of
biological communities

• Solar radiation varies with latitude because of
  earths curvature.
• At the equator, sunlight
  strikes the most directly
  (perpendicularly).
• Moving away from the
  equator toward the poles,
  the suns rays strike
  Earth at an angle, so
  same amount of solar
  energy is not spread over a
  greater area
• Result regions near the equator absorb more heat
  than areas of comparable size in more northern or
  southern latitudes.

10
Regional climate influences the distribution of
biological communities

• The Earths tilt causes the seasons.
• The Northern hemisphere is tipped most toward the
  sun in June, resulting in the long days of summer
  (winter in the S. hemisphere).
• Longest days in the S. hemisphere
  occur in December
  (our
  shortest days).
• The tropics (btwn
  Tropic of Cancer
  Tropic of Capricorn
  receive the most
  input
  of sunlight and
  the least seasonal
  variation in sunlight.

11
Uneven heating of the earth causes rain and winds

• The tropics high temps causes water to evaporate
  and rise--low wind (the doldrums) as warm air
  rises, it starts to cool, releasing water as
  rain.
• Now-dry air then moves away from equator, cools,
  and then descends, absorbing moisture from the
  land, causing deserts at 30º
  latitude this also causes
  the
  trade winds.
• Temperate zones
  (30º-60º latitude) air
  absorbs
  moisture, but
  drops it as rain b/c
  temperatures here are
  lower
  these areas are
  therefore cool and moist.

Figure 34.6C
12
Prevailing winds

• Major global air movements.
  (shown as pink arrows)
• Result from combined effects of
• 1) the rising and falling of air
  masses (blue and brown
  arrows) and
• 2) The Earths rotation
  (large gray arrows)

Ocean currents

• Result from combination of prevailing winds,
  planets rotation, unequal heating of surface
  waters, and locations shapes of the continents.

13
Oceans moderate the climate of nearby land

• Why? (review from Chp. 2)
• Because of H-bonding, water resists change in
  temperature.

• When water is heated, the heat energy disrupts
  the H bonds first, and then begins to increase
  the temp.
• When water is cooled, more H bonds form,
  releasing energy and slowing the cooling process.

14
Landforms affect local climate

• Temperature drops w/altitude
• For every 1,000-m increase in elevation, there is
  a temperature drop of 6º.
• Rainshadow effect
• Describes how mountains affect rainfall.
• As moist air moves toward a mountain range, it
  flows upward, cools at the higher altitude, and
  drops all the water in the air (lots of rain
  and/or snow).
• On the other side
  
  of the mountain
  range,
  there is little
  rain,
  and the
  descending air
  
  absorbs moisture
  
  from the air,
  
  creating desert
  
  conditions.

15
Aquatic biomes

• Include
• 1) Ocean (saltwater) biomes
• 2) Freshwater biomes

Oceans

• Life originated in the ocean
• it took almost 3 billion years before life
  existed on land.
• Oceans cover 75 of the earths surface.
• Evaporation of oceans produces most of the
  Earths rainfall.
• Photosynthesis by marine algae and cyanobacteria
  supplies a substantial portion of the biospheres
  oxygen.

16
Ocean biomes

• Influenced by abiotic factors such as amount of
  light and distance from the shore.
• Intertidal zone area of shore where land meets
  the ocean.
• Pelagic zone
  the open ocean
• Benthic zone
  the sea floor

Figure 34.7B
17

• A close-up view of the intertidal zone . . .
• Intertidal zones are home to many diverse
  organisms.
• Underwater during
  high tide.
• Exposed to sun and
  wind during low tide.

A tidepool on the coast of central California
18

• Deep sea submersibles are providing new
  information about life in the benthic zone.

The Deep Sea submersible Alvin
Hydrothermal vents
Tube worms
19

• Coral reefs.
• Shallow benthic communities.
• Found in warm, tropical waters.
• Reef is built up slowly by many generations of
  coral animals and algae.
• Support a huge
  diversity of
  invertebrates
  and fish.
• Easily degraded
  by pollution.

20

• Estuaries.
• Areas where a freshwater stream or river merges
  with the ocean.
• Saltiness is in between that of oceans (3 salt)
  to that of freshwater (
• Very diverse due to mixing of two types of
  habitats.
• Crucial nesting and
  feeding areas for
  waterfowl.
• Wetland an area
  that is transitional
  between an aquatic
  ecosystem and a
  terrestrial one.

21
Photic vs. aphotic zones

• Photic zone any ocean areas that receive light.
• This is where photosynthesis occurs.
• Relatively small portion of ocean water.
• Aphotic zone vast, dark region underlying photic
  zone--no photosynthesis.
• Species here often
  depend on food drifting
  
  down from above.
• Near ocean vents, there
  are also bacteria
  that
  obtain energy from
  chemical sources
  such
  as hydrogen sulfide
  instead of
  from sunlight.

22
Freshwater biomes

• Include lakes, ponds, rivers, streams, and
  wetlands.
• Factors that shape lake pond communities are
• Light, temperature, and the availability of
  nutrients and dissolved oxygen
• Also have photic and aphotic zones, as well as
  benthic (bottom-dwelling) communities.
• Lakes and ponds undergo seasonal mixing due to
  temperature that is critical for nutrient and
  oxygen availability.
• In the summer, the top layer is warm, and
  nutrients released by decomposers become trapped
  at the bottom, out of reach of photosynthetic
  organisms.
• In the winter, the surface water cools, becomes
  denser, and sinks, allowing mixing with the
  deeper water and upswelling of nutrients to the
  surface--also brings oxygen down to the bottom.

23
Fertilizer and sewage runoff dumps excess
nutrients into freshwater biomes

• Sewage and fertilizer from lawns and agricultural
  fields enter lakes and rivers.
• Dumping lots of nutrients, like nitrogen
  phosphorus.
• This leads to algal blooms, or population
  explosions of algae.
• Heavy growth of algae reduces light penetration
  into the water.
• When the algae die and decompose, this can cause
  severe oxygen depletion in the lake or river.

24
River and stream ecosystems change dramatically
from their source to their mouth

• At the source (a spring, or a snowmelt)
• Water is usually cold, low in nutrients, and
  clear.
• Channel is usually narrow, with a swift current
  that creates a rocky bottom and little growth
  of phytoplankton.
• At the mouth (where it empties into
  lake or ocean)
• Water becomes warmer, murkier, and
  more nutrient-rich.
• Channel is wider, current is slow,
  bottom is silty

25
Terrestrial biomes

• Distribution of the 8 major types of terrestrial
  biomes largely depends on climate (mostly temp.
  rainfall).
• Similar types of biomes tend to occur in
  geographical areas w/similar climates (see map)
• This is due to convergent evolution (see chp.
  15.6)

26
Tropical forests

• Cluster near the equator, where temp. is warm and
  days are 11-12 hours long all year.
• can be dry forests or tropical rain forests
  (200-400cm rainfall/year) (shown in picture)

27
Tropical rain forests

• Are the most diverse ecosystem, providing habitat
  for a very large number of different species.
• Soils of tropical rain forests are typically
  nutrient-poor, b/c high temps and lots of rain
  lead to rapid decomposition rather than a buildup
  of organic material.
• Many tropical rain forests have been cleared for
  mining or lumber, then farmed for a few seasons,
  then abandoned.
• After being stripped, tropical rain forests
  recover very quickly because of the nutrient-poor
  soils.

28
Savannas

• Grasslands w/scattered trees.
• Climate is dry (30-50cm rainfall/year) and warm.
• Frequent fires and grazing animals inhibit
  further growth of trees (the dominant plants are
  fire-adapted).
• Many large herbivores live here (giraffes,
  zebras, antelopes, lions.

29
Deserts

• Driest of the biomes (
• Temperatures may be extremely hot or very cold.
• Desert plants typically produce great numbers of
  seeds, which remain dormant until a heavy rain
  triggers germination.
• Desert animals have special adaptations to
  conserve water.
• Desertification
  conversion of
  non-desert
  
  regions to desert,
  a
  significant problem
  due to overgrazing
  and
  overfarming.

30
Chaparral

• A region of dense, spiny shrubs with tough,
  evergreen leaves.
• Occurs in Mediterranean climates, (S. Europe, N.
  Africa, middle East, and here).
• Vegetation is adapted to periodic fires.
• Fires are actually required for long-term
  maintenance of chaparral ecosystem.

Los Padres National Forest In California
31
Temperate grasslands

• Grasslands mostly treeless except along rivers
  or streams.
• Found in regions of relatively cold winter temps.
• Persist due to drought, fires, and grazing, which
  inhibit the growth of woody plants.
• Little remains of North American prairies
  today--most is intensively
  farmed, and is
  very
  productive
  agricultural land.

32
Temperate forests

• Dominated by broadleaf trees (ex hickory, birch,
  maple).
• Grow throughout midlatitude regions, where there
  is enough moisture to support the growth of large
  trees (most of Eastern US, central Europe, parts
  of E. Asia and Australia).
• Forests are more open than tropical rain forests
  and are not as tall or as diverse.
• Soils are rich in nutrients.
• Almost all of the
  original broadleaf
  forests in N.
  America
  were destroyed by logging
  and clearing for
  agriculture
  and urban development
  in contrast to other
  ecosystems,
  these forests can recover
  after
  disturbance.

33
Coniferous forests

• Dominated by a few species of cone-bearing
  evergreen trees (e.g. spruce, pine, fir,
  hemlock).
• Climate long, cold winters, and short, wet
  summers.
• Soil is nutrient-poor, thin, and acidic--forms
  slowly b/c of the slow decomposition of conifer
  needles.
• There are also coniferous forests in coastal
  North America that are actually temperate rain
  forests
• These are dominated by redwoods, Douglas fir, and
  hemlock trees.
  (see picture,
  
  showing a
  coniferous
  forest
  in Oregon).

Figure 34.16
34
Tundra

• Occur at northernmost limits of plant growth and
  at very high altitudes no trees.
• Treeless biome characterized by extreme cold,
  wind, and permafrost--subsoil that is always
  frozen.
• Arctic tundra encircles the North pole and
  extends south to the coniferous forests.
• Alpine tundra is found above the treeline on high
  mountains.
• Climate
• extremely cold w/
  little light for a
  long time.
• Brief summer, when plants
  grow quickly and flower in
  
  a rapid burst.