Download Ecosystems, Energy Flow, Evolution, Cycles

Ecosystems, Energy Flow,
Evolution, Cycles
5-10% of your APES Exam
Ecology
• Species that can naturally mate together and form fertile and
viable off spring are called Species.
• Organisms of the same species (intraspecific) that interact
with each other and live in the same area form a population
• Populations that interact with different species (interspecific)
but live in the same area are called communities
• When these communities interact with their environment it’s
called and ecosystem.
• Different ecosystems make up a biosphere
• Species -> Population-> Community-> Ecosystem -> Biosphere
Population Dispersion
Ecosystem Characteristics
• 1. Physical Appearance- Relative size;
stratification and distribution of populations and
species
• 2. Species Diversity: number of different species
• 3. Species Abundance: Number of individuals in
each species
• 4. Niche Structure: Number of ecological niches;
how they resemble or differ from each other;
species interaction
Ecological Niches
• An organisms “job” in the ecosystem
• Described by its adaptive traits, habitat and
place in the food web
• Generalists (cockroaches, mice, humans) have
broad Niches
• Specialists (pandas) have narrow Niches
Competitive Exclusion Principle
• When 2 species are able to live and thrive in
the same environment until you put them
together.
Competition
• Intraspecific (between same species) or
Interspecific (between different species)
• Driving force of evolution
• Interference Competition: preventing another
organism from getting to its resource
• Exploitation Competition: using a resource so
it depletes and others can’t use it
Amensalism
• Interaction with 2 species where one suffers
and the other doesn’t benefit at all.
• Example: The bread mold Penicillium secrets
penicillin which is a chemical that kills
bacteria.
• Example: Black walnut tree secretes a
chemical that kills neighboring plants.
Commensalism
• Interaction with 2 species where one benefits
and the other is not affected
• Example: Remora on Shark (just needs a ride)
• Example: Orchids living on Trees (just needs a
home)
• Example: Hermit crabs using left over shells of
marine life (using something another has
created)
Mutualism
• Interaction where both species benefits
• Example: Bees Pollinating Flowers, Flowers
feeding Bees
Parasitism
• One benefits and the other is harmed.
• Example: Tick and Dog
Keystone Species
• This organisms presence contributes to a
diversity of live and whose extinction would
lead to extinction of other organisms. Also
prevents over population.
• Example: Sea Otters in a Kelp Forest
• Example: Grizzly Bears moving nutrients from
rivers to forests by way of salmon
• Example: Sea Stars praying on Urchins and
Mussels this keeps their populations down.
Biomes
Biome
Antarctic
Surrounding South Pole. Rainfall <2 cm per year
Benthos
Bottom of the ocean. No sunlight, no plant life. Dead organisms recycle
matter, chemosynthesis
Coastal Zones
Estuaries, wetlands, coral reefs. High diversity and counts of plants and animal
species due to runoff from land
Coral Reefs
VERY Diverse, VERY sensitive- disappearing at an alarming rate
Deserts
Form 15-25 degrees north and south of the equator. Rainfall <20 cm per year.
Soils often have abundant nutrients but lack organisms.
Freshwater
Lakes
Includes swamps, bogs, and wetlands. Important breeding areas for insects
and amphibians, Critical for water supply. Easily polluted. Oligotrophic lakes
are clear and low in nutrients. Eutrophic Lakes are rich in nutrients and life.
Grasslands
Rainfall is seasonal. Too wet for deserts, too dry for forests. 25% of all land.
Overused for agriculture. Few plants because of fires and water availability
Biomes
Biome
Hydrothermal
Vents
Occur in the deep ocean where hot-water vents rich in sulfur compounds are
found and provide energy for chemosynthetic bacteria
Intertidal
Lots of biodiversity. Area between high and low tide. Water movement brings
nutrients and removes wastes. Sensitive to pollution
Ocean
75% of earths surface. Low diversity and productivity except near shoreline.
Low nitrogen and phosphorus = limited plant growth and small organisms
Savanna
Warm year-round. Scattered trees. Intermediate between grasslands and
forest. Extended dry season followed by rainy season. Contains herding
animals.
Taiga/Coniferous Found between 45-60 degrees north latitude. 17% of land surface. 2 types:
/Boreal Forest
open woodland and dense forests. More precipitation than the tundra. Soils
are acidic b/c of decomposing tree needles.
Temperate
Found in milder temp than Taiga. Rapid decomposition. Exploited by humans.
Deciduous forest Tall deciduous trees. Low density of large mammals.
Temperate Rain
Forest
100+ inches of rain each year. Lack of light to lower layers = less diversity
Biomes
Biome
Chaparral/ Scrubland
Hot dry summers, mild cool winters. Dense shrub growth. Erosion
common after fires
Temperate Woodlands
Drier climate than deciduous forests. Fires common. Dominate by
small trees.
Tropical Rain Forests
Very Diverse. Lots of Rain. High contrast in temps. Found within
Hadley cells. Soil nutrients are low. Quick decomposition
Tundra
60 degrees and above north latitude. Influenced by polar cells.
Permafrost abundant. Low vegetation= low soil nutrients
Photosynthesis/Cellular Respiration
• Plants remove CO2 from atmosphere and convert it to
carbohydrates (glucose) and other organic compounds.
• Plants capture light energy in the chlorophyll.
• Glucose is derived from its oxidation during cellular
respiration
• Oxygen gas is then released into the atmosphere
• Cellular respiration is the opposite of photosynthesis.
• In respiration, glucose is oxidized to produce CO2,
Water and chemical energy (ATP)
Photosynthesis
Cellular Respiration
Food Webs
Food Webs
Ecological Pyramids
• Sunlight is the ultimate source of energy for
most biological processes
• Less than 3% of the sun that reaches earth is
used for photosynthesis
• In a food chain, only 10-20% of the energy is
passed up to the next level.
• The other 80-90% is lost
Ecological Pyramids
Ecological Pyramids
Biodiversity
• Genetic diversity: range of all genetic traits,
both expresses and recessive, that makes up
the gene pool for a species.
• Species diversity: the number of different
species that live in a certain area.
• Ecosystem diversity: range of habitats that can
be found in a defined area, bother biotic and
abiotic components.
Biodiversity
Diversity Increasers
Diversity Decreasers
• Diverse Habitats
• Disturbance in the habitat
(fire, storms etc)
• Environmental conditions
with low variations
• Trophic levels with high
diversity
• Middle states of succession
• Evolution
• Environmental stress
• Extreme environments
• Extreme limitations in the
supply of a fundamental
resource
• Extreme amounts of
disturbances
• Introduction of new species
from a different area
• Geographic Isolation
Evolution
• Supported by structural evidence and the
fossil record
• Macroevolution: Long term, large scale
changes to a population
• Microevolution: small genetic changes to a
population
Speciation
• When a segment of the population becomes
so isolated that gene flow stops and those
members of the population can no longer
mate successfully with the rest of their
species.
• Adaptive Radiation: rapid speciation to fill
ecological niches and is driven by natural
selection or mutation
Isolation
• Geographic Isolation: a geographic barrier
prevents species from mating and eventually
leads to speciation.
• Pre-mating isolation: things that isolate species
BEFORE they get a chance to mate Example:
Mating times, nocturnal species, anatomy
• Post-Mating Isolation: things that prevent
gametes from being fertilized or fertile offspring
from being born. Example: baby kills mother,
sperm doesn’t fertilize egg.
Convergent Evolution
• Process where organisms not closely related
to each other independently acquire similar
(analogous) characteristics while evolving in
separate and varying ecosystems
• Examples: Insects, birds and bats all have
wings
Evolutionary Relay
• Occurs when independent species acquire
similar characteristics through their evolution
in similar ecosystems although not at the
same time.
• Example: development of dorsal fin in sharks
and in extinct marine reptiles.
Parallel Evolution
• 2 independent species evolve together at the
same time and in the same ecosystem and
acquire similar characteristics.
• Example: similar patterns in leaves have
occurred on different plants over and over
again
Gradualism
• Evolution is a very slow and stepwise process
over millions of years.
Punctuated Equilibrium
• Some species arose suddenly in a short period
of time (thousands of years). After long
periods of stability.
• These bursts are thought to have happened
because of a quick change in the environment
• Example: flowering plants appeared without
any pre-flowering plants in the fossil record
Ecological Services
• The following are some services ecosystems give us.
–
–
–
–
–
–
–
–
–
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Moderate weather extremes
Disperse seeds
Mitigate drought and floods
Protect people from the sun’s rays
Cycle and move nutrients
Protect waterways from erosion
Detoxify wastes
Purify air and water
Pollinate crops
Regulate disease carrying organisms
Control pests
Maintain biodiversity
When an essay
question asks:
What ecological
services does
______ provide…
Succession
• Gradual and orderly change in an ecosystem with the
goal to be a “Climax Community”
• Sometimes this means starting over after a disturbance
(fire, earthquake, flood)
• Rates of succession are determined by
– Facilitation: one species modifies and environment to the
extent it meets the needs of another species
– Inhibition: when one species modifies the environment to
an extent that it is not suitable for another species
– Tolerance: when species are not affected by the presence
of other species.
Early Succession
• Early successional species are generalists
(Pioneer species)
• They have short reproductive times and low
biomass and fast reproductive rates (R-Select).
Late Succession
• Late successional species include larger
perennial plants and animals with greater
biomass. They have longer generational times
and higher parental care (K-select).
Types of Succession
Type
Description
Allogenic
Changes in the environment that make conditions
beneficial to new plant communities
Primary
The colonization and establishment of pioneer species
on bare ground (lichen and moss)
Progressive
Communities become more complex over time by having
a higher species diversity and greater biomass
Retrogressive The environment deteriorates and results in less
biodiversity and biomass
Secondary
Begins in an area where the natural community has been
disturbed but topsoil remains (after a forest fire or flood)
Succession
Carbon Cycle
• Carbon is the basic building block of life and a
fundamental element found in carbohydrates,
fats, proteins and nucleic acids.
Carbon Cycle
• Carbon “SINKS”
– Plant Matter: a portion of atmospheric carbon is
removed by photosynthesis and is incorporated
into plant structures
– Terrestrial Biosphere: freshwater systems and
nonliving organic material are included. Forests
store 86% of the planet’s above ground carbon
and 73% of the planet’s soil carbon. Carbon can be
stored here for several hundreds of years in trees
and several thousands of years in soils
Carbon Cycle
• Carbon SINKS cont.:
– Oceans: Dissolved inorganic carbon in the form of
CO2. Living and nonliving marine biota included
(shells, skeletons). Removing carbon dioxide from
the water raises the pH making the ocean more
basic.
– Sedimentary Deposits: Limestone and carbon
trapped in fossil fuels and coal. Limestone is the
largest reservoir of carbon in the carbon cycle
Carbon Cycle
• Carbon is released into the atmosphere through:
– Cellular respiration of plants and animals (CO2).
Anaerobic respiration releases carbon in the form of
methane (CH4).
– Decay of organic matter by decomposers, if oxygen is
present it’s released as CO2. If no oxygen it’s released
as CH4.
– Burning of fossil fuels, wood, coal etc.
– Volcanic eruptions
– Weatherization of rocks- this breaks down to CO2 or
carbonic acid H2CO3
– Release of carbon dioxide by warmer water
Carbon Cycle
Nitrogen Cycle
• Nitrogen makes up 78% of the atmosphere
• Essential in the formation of amino acids,
proteins and nucleic acids.
Nitrogen Cycle- Nitrogen Fixation
• Converts N2 into ammonia (NH3) or Nitrate (NO3-)
• 10% of nitrogen fixing is through high-energy
fixation (lightening) where Nitrogen and oxygen
combine to form nitrates which are carried to the
surface in rainfall as Nitric Acid (HNO3)
• Biological Fixation (90%)- Molecular nitrogen (N2)
is split into 2 free nitrogens, then attach to an
hydrogen to from ammonia (NH3).
Nitrogen Cycle- Nitrogen Fixation
• Fixation process is accomplished by several
microorganisms (Rhizobium is associated with
the root nodules of legumes)
• Free-living aerobic bacteria Azobacter and
Clostridium in the soil also fix nitrogen.
• The end product here is ammonia
Nitrogen Cycle- Nitrification
• This is when ammonia (NH3) is oxidized to
nitrite (NO2-) or nitrate (NO3-)- these forms
are most useable by plants.
• Nitrosomanas oxidize ammonia to nitrite and
water
• Nitrobacter oxidize nitrite to nitrate
• Microorganisms are essential in this process
Nitrogen Cycle- Assimilation
• Nitrates are the form of nitrogen most commonly
assimilated by plants through root hairs.
• Rains and extensive irrigation can leach soluble
nitrates and nitrites into groundwater (too much of this is
the water can interfere with blood-oxygen levels in infants)
• Soluble nitrates run off the land and into aquatic
areas causing cultural eutrophication
• Animals assimilate nitrogen-based compounds by
consuming plants or other organisms that
consume plants
Nitrogen Cycle- Ammonification
• When a plant or animal dies, or an animal
excretes, the initial form of nitrogen is found
in amino acids and nucleic acids.
• Bacteria and sometimes fungi, convert this
organic nitrogen back into ammonia (NH3)
Nitrogen Cycle- Denitrification
• When nitrates are reduced to gaseous
nitrogen.
• This process is used by facultative anaerobes.
• These organisms flourish in an aerobic
environment but also break down NO3- in
anaerobic environments to use the oxygen
and release the nitrogen
• Examples include fungi and bacteria
Pseudomonas
Nitrogen Cycle
Nitrogen Cycle
• Humans activity has more than doubled the
annual transfer of nitrogen to the biologically
available forms through:
– Extensive cultivation of legumes
– Extensive use of chemical fertilizer
– Pollution emitted by vehicles and industrial plants
(NOx)
– Biomass burning
– Cattle and feedlots
– Industrial processes
Bad forms of Nitrogen
• Fossil fuel combustion (NOx)
• NOx is a precursor of tropospheric ozone
production and contributes to smog and acid rain
• Ammonia (NH3) in the atmosphere has tripled
since the Industrial Revolution. Ammonia acts as
an aerosol and decreases air quality
• Nitrous Oxide(N2O) a significant greenhouse gas
and breaks down atmospheric (good) ozone
Phosphorus Cycle
• Essential for the formation of nucleotides, ATP
fats in the cell membrane, bones, teeth and
shells.
• Not found in the atmosphere
• Generally found as phosphates (PO4-) or
hydrogen phosphate ion (HPO4)
• Often a limiting factor in soils because of its
low concentration and solubility.
Phosphorus Cycle
• Phosphorus is slowly released from terrestrial
rocks by weathering and acid rain
• It then dissolves into the soil and is taken up
by plants
Phosphorus Cycle
• Human impacts on the cycle:
– Mined large quantities of rocks containing
phosphorus for inorganic fertilizers and detergents
– Clear-cutting tropical habitats for agriculture
– Allow runoff from feedlots, from fertilizers and
from the discharge of sewage plants leading to
cultural eutrophication
– Humans apply phosphorous to fields for fertilizer.
Phosphorus Cycle
Sulfur Cycle
• Found mostly in underground rocks and deep
oceanic deposits.
• Natural release of sulfur into the atmosphere
if from weathering of rocks and gasses
released from seafloor vents and volcanic
eruptions
• It is released mainly as hydrogen sulfide (H2S)
and sulfur dioxide (SO2)
Sulfur Cycle
• Once in the atmosphere is it converted to
sulfur trioxide (SO3) and sulfuric acid H2SO4.
• The acid mixes with rain and falls back to the
surface as acid rain.
• Sulfate (SO4-2) salt particles enter the
atmosphere from sea spray, dust storms and
forest fires.
• These sulfate ions are eventually absorbed by
plants to make proteins.
Sulfur Cycle
• Humans effect this cycle by:
– Refining and burning fossil fuels
– Converting (smelting) sulfur-containing metallic
mineral ores into free metals such as copper, lead
and zinc
Water Cycle
• Powered by the Sun’s energy and Gravity
• Oceans hold 97% of all the water on the planet
are the source of 78% of global precipitation.
• Oceans are the source of 86% of all global
evaporation and this keeps the surface of the
earth from overheating
• The water cycle is in a state of dynamic
equilibrium- evaporation= precipitation
• Warm air holds more water that cold air.
Water Cycle
Human Activity
Effect on Water Cycle
Withdrawing water from lakes, aquifers and
rivers
Groundwater depletion and saltwater intrusion
Clearing land for agriculture and urbanization
Increases runoff, Decreased infiltration,
increased flood risk, accelerated soil erosion
Agriculture
Runoff contains nitrates, phosphates,
ammonia etc.
Destruction of wetlands
Disturbing natural processes that purify water
Pollution of water
Increased occurrences of infectious agents
such as cholera, dysentery, etc.
Sewage runoff, feedlot runoff
Cultural eutrophication
Building power plants
Increased thermal pollution
Water Cycle