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Ecology
Ecology
Ecology
• The study of interaction among organisms and between organisms and their environment
Niche
Fig. 3-2, p. 51
Communities
Subatomic Particles
Atoms
Molecules
Protoplasm
Cells
Tissues
Organs
Organ systems
Organisms
Populations
Populations
Communities
Ecosystems
Biosphere
Earth
Planets
Solar systems
Galaxies
Universe
Organisms
Realm of ecology
Ecosystems
Biosphere
Widely separated regions share similarities
• Biome = major regional complex of similar communities recognized by– Plant type– Vegetation
structure
A variety of factors determine the biome
• The biome in an area depends on a variety of abiotic factors – Temperature, precipitation,
atmospheric circulation, soil• Climatographs
– A climate diagram showing an area’s mean monthly temperature and precipitation
– Similar biomes occupy similar latitudes
Desert
• Minimal precipitation• Some deserts are bare, with
sand dunes (Sahara)• Some deserts are heavily
vegetated (Sonoran)• They are not always hot
– Temperatures vary widely• Saline soils• Nocturnal or nomadic animals• Plants have thick skins or spines
DESERT BIOMES
• Variations in annual temperature (red) and precipitation (blue) in tropical, temperate and cold deserts.
Figure 5-12
Boreal forest (taiga)
• Canada, Alaska, Russia, Scandinavia
• Variation in temperature and precipitation
• Cool and dry climate– Long, cold winters – Short, cool summers
• Poor and acidic soil• Few evergreen tree
species• Moose, wolves, bears,
migratory birds
Tropical rainforest
• Central America, South America, southeast Asia, and west Africa
• Year-round rain and warm temperatures
• Dark and damp• Lush vegetation• Variety of animals and tree
species, but in low numbers• Very poor, acidic soils
Temperate deciduous forest
• Deciduous trees lose their leaves each fall and remain dormant during winter
• Mid-latitude forests in Europe, East China, Eastern North America
• Fertile soils• Forests = oak, beech, maple
Temperate grasslands• More extreme temperature
difference between winter and summer
• Less precipitation• Also called steppe or prairie
– Once widespread throughout parts of North and South America and much of central Asia
– Much was converted for agriculture
– Bison, prairie dogs, antelope, and ground-nesting birds
Savanna
• Grassland interspersed with trees
• Africa, South America, Australia, India
• Precipitation only during rainy season
• Water holes• Zebras, gazelles, giraffes,
lions, hyenas
Tundra
• Canada, Scandinavia, Russia • Minimal precipitation
– Nearly as dry as a desert• Seasonal variation in
temperature– Extremely cold winters
• Permafrost: permanently frozen soil
• Few animals: polar bears, musk oxen, caribou
• Lichens and low vegetation with few trees
Chaparral
• Mediterranean Sea, California, Chile, and southern Australia
• High seasonal– Mild, wet winters– Warm, dry summers
• Frequent fires• Densely thicketed,
evergreen shrubs
Tropical dry forest
• Tropical deciduous forest• India, Africa, South
America, northern Australia
• Wet and dry seasons• Warm, but less rainfall• Converted to agriculture• Erosion-prone soil
Temperate rainforest
• Coastal Pacific Northwest region
• Great deal of precipitation• Coniferous trees: cedar,
spruce, hemlock, fir• Moisture-loving animals
– Banana slug• The fertile soil is susceptible
to erosion and landslides• Provides lumber and paper
Altitudes create patterns
• Vegetative communities change along mountain slopes– In the Andes, a mountain
climber would begin in the tropics and end up in a glacier
Hiking up a mountain in the southwest U.S. is analogous to walking from Mexico to Canada
Definition
• The many forms of life found on the Earth. “Wildness”– Genetic Diversity – the variety of genetic
make-up w/in a single species– Species Diversity – the variety of species in
different habitats on the Earth
Biodiversity
Producers: Basic Source of All Food
• Most producers capture sunlight to produce carbohydrates by photosynthesis:
The process in which glucose is synthesized by plants.
Photosynthesis
Producers• An organism that uses solar energy (green
plant) or chemical energy (some bacteria) to manufacture its food.
Consumers: Eating and Recycling to Survive
• Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains.– Herbivores
• Primary consumers that eat producers– Carnivores
• Primary consumers eat primary consumers• Third and higher level consumers: carnivores that eat
carnivores.– Omnivores
• Feed on both plant and animals.
Decomposition
• As plant or animal matter dies it will break down and return the chemicals back to the soil.
• This happens very quickly in tropical rainforest which results in low-nutrient soils.
• Grasslands have the deepest and most nutrient rich of all soils
Decomposer (scavenger, detritivore)
• An organism that digests parts of dead organisms, cast-off fragments, and wastes of living organisms. Ex. bacteria and fungi.
Decomposers and Detrivores
– Decomposers: Recycle nutrients in ecosystems.– Detrivores: Insects or other scavengers that feed on
wastes or dead bodies.Figure 3-13
Fig. 3-14, p. 61
Abiotic chemicals(carbon dioxide,
oxygen, nitrogen, minerals)
Heat
Heat
Heat
Heat
Heat Solarenergy
Consumers(herbivores, carnivores)
Producers(plants)
Decomposers(bacteria, fungi)
Primary Consumer (herbivore)• An organism that feeds directly on
all or parts of plants.
Secondary Consumer (carnivore)• An organisms that feeds only on
primary consumers. Most are animals, but some are plants (Venus fly-trap).
Tertiary Consumer (carnivore)• Animals that feed on animal-eating
animals. Ex. hawks, lions, bass, and sharks.
Quaternary Consumer (carnivore)• An animal that feeds on tertiary
consumers. Ex. humans.
Food Webs/Chains• Purpose – determines
how energy & nutrients move from one organism to another through the ecosystem
• Arrows – point from the producer to the consumer
Fig. 3-17, p. 64
Heat
Heat
Heat
Heat
Heat
Heat Heat Heat
Detritivores (decomposers and detritus feeders)
First Trophic Level
Second TrophicLevel
Third Trophic Level
Fourth Trophic Level
Solar energy
Producers(plants)
Primary consumers(herbivores)
Secondary consumers(carnivores)
Tertiary consumers
(top carnivores)
Structure• Shows the decrease in usable energy
available at each succeeding trophic level in a food chain or web.
10% Rule
• We assume that 90% of the energy at each energy level is lost because the organism uses the energy. (heat)
• It is more efficient to eat lower on the energy pyramid. You get more out of it!
• This is why top predators are few in number & vulnerable to extinction.
Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
• In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.
Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
• Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next.
Figure 3-19
Energy Flow & Feeding Relationships• Direction:
grain steer human• Measurement – samples are taken,
dried, & weighed
Niche
Competition
Predator• An organisms that captures & feeds on
parts or all of another animal.
Prey• An organisms that is captured & serves
as a source of food for another animal.
Description• Two kinds of organisms, such as
lions and zebras, are said to have a predator-prey relationship.
Cycle• See graph (page 203 and 204)
Importance in Population Control• Predators usually kill the sick, weak or aged.
• This helps to let the rest of the prey have greater access to the available food supply.
• It also improves the genetic stock.
SPECIES INTERACTIONS: COMPETITION AND PREDATION
• Species can interact through competition, predation, parasitism, mutualism, and commensalism.
• Some species evolve adaptations that allow them to reduce or avoid competition for resources with other species (resource partitioning).
Antipredator Defenses
Symbiosis
• Parasitism –when 1 species (parasite) feeds on part of another species (host) by living on or in it for a large portion of host's life.
• Commensalism – benefits one species but doesn't harm or help the other
• Mutualism – both species benefit
Parasites: Sponging Off of Others
• Although parasites can harm their hosts, they can promote community biodiversity.– Some parasites live in host (micororganisms,
tapeworms).– Some parasites live outside host (fleas, ticks,
mistletoe plants, sea lampreys).– Some have little contact with host (dump-nesting
birds like cowbirds, some duck species)
Mutualism: Win-Win Relationship
• Two species can interact in ways that benefit both of them.
Figure 7-9
Fig. 7-9a, p. 154(a) Oxpeckers and black rhinoceros
Commensalism: Using without Harming
• Some species interact in a way that helps one species but has little or no effect on the other.
Figure 7-10
Changes in Ecosystems:Ecological Succession
Definition:
• Natural, gradual changes in the types of species that live in an area; can be primary or secondary
• The gradual replacement of one plant community by another through natural processes over time
Primary Succession
• Begins in a place without any soil – Sides of volcanoes– Landslides– Flooding
• Starts with the arrival of living things such as lichens that do not need soil to survive
• Called PIONEER SPECIES
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Primary Succession
• Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
• When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil
Primary Succession
• Simple plants like mosses and ferns can grow in the new soil
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http://www.uncw.edu
Primary Succession
• The simple plants die, adding more organic material
• The soil layer thickens, and grasses, wildflowers, and other plants begin to take over
http://www.cwrl.utexas.edu
Primary Succession
• These plants die, and they add more nutrients to the soil
• Shrubs and tress can survive now
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Primary Succession
• Insects, small birds, and mammals have begun to move in
• What was once bare rock now supports a variety of life
http://p2-raw.greenpeace.org
Secondary Succession
• Begins in a place that already has soil and was once the home of living organisms
• Occurs faster and has different pioneer species than primary succession
• Example: after forest fires
Climax Community
• A stable group of plants and animals that is the end result of the succession process
• Does not always mean big trees– Grasses in prairies– Cacti in deserts
Habitat Needs• Cover – shelter; trees, shrubs, etc.• Water• Nutrients
Macronutrients
• Chemicals organisms need in large numbers to live, grow, and reproduce.
• Ex. carbon, oxygen, hydrogen, nitrogen, calcium, and iron.
Micronutrients
• These are needed in small or even trace amounts.
• Ex. sodium, zinc copper, chlorine, and iodine.
Carbon, Phosphorous, and Nitrogen Cycles
• The cyclic movement of chemicals (see overhead).
• Carbon cycle: pg 73-74• Phosphorous cycle: pg 76• Nitrogen cycle: pg 74-76• Sulfur cycle: pg 77-78
Fig. 3-7, p. 55
Nitrogencycle
Biosphere
Heat in the environment
Heat Heat Heat
Phosphoruscycle
Carboncycle
Oxygencycle
Watercycle
CARBON CYCLE
Effects of Human Activities on Carbon Cycle
• We alter the carbon cycle by adding excess CO2 to the atmosphere through:– Burning fossil fuels.– Clearing vegetation
faster than it is replaced.
Figure 3-28
Phosphorous Cycle
Effects of Human Activities on the Phosphorous Cycle
• We remove large amounts of phosphate from the earth to make fertilizer.
• We reduce phosphorous in tropical soils by clearing forests.
• We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.
Phosphorus
• Bacteria are not as important in the phosphorus cycle as in the nitrogen cycle.
• Phosphorus is not usually found in the atmosphere or in a gas state only as dust.
• The phosphorus cycle is slow and phosphorus is usually found in rock formations and ocean sediments.
• Phosphorus is found in fertilizers because most soil is deficient in it and plants need it.
• Phosphorus is usually insoluble in water and is not found in most aquatic environments.
Nitrogen Cycle
Effects of Human Activities on the Nitrogen Cycle
• We alter the nitrogen cycle by:– Adding gases that contribute to acid rain.– Adding nitrous oxide to the atmosphere through
farming practices which can warm the atmosphere and deplete ozone.
– Contaminating ground water from nitrate ions in inorganic fertilizers.
– Releasing nitrogen into the troposphere through deforestation.
Effects of Human Activities on the Nitrogen Cycle
• Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.
Figure 3-30
Nitrogen Fixation
• This is the first step of the nitrogen cycle where specialized bacteria convert gaseous nitrogen to ammonia that can be used by plants. This is done by cyanobacteria or bacteria living in the nodules on the root of various plants.
Nitrification
• Ammonia is converted to nitrite, then to nitrate
Plant roots absorb ammonium ions and nitrate ions for use in making molecules such as DNA, amino acids and proteins.
Assimilation
Ammonification• After nitrogen has served its purpose in
living organisms, decomposing bacteria convert the nitrogen-rich compounds, wastes, and dead bodies into simpler compounds such as ammonia.
Denitrification•Nitrate ions and nitrite ions are converted into nitrous oxide gas and nitrogen gas.This happens when a soil nutrient is reduced and released into the atmosphere as a gas.
Population Ecology
Populations are characterized by three things:
o Geographic Distributiono Densityo Growth Rate
Population Density
o The number of individuals in a given areao Found in different dispersal patters:
Population Growth Curves
o Population growth curves determine the rate at which a population grows.
o There are two types of growth curves:o Exponential o Logistical
Exponential Growth Curve
o Under ideal conditions with unlimited resources, a population will grow at a constant rate
Logistic Growth Curve
• After a period of exponential growth, resources become less available and the growth slows or stops.
How to Read the Logistic Curve
1. Lag phase2. Exponential phase3. Stationary phase4. Death phase
Survivorship Curves
Type 1- Most mortality occurs among elderlyType 2- Mortality is not dependent on ageType 3- High rate of juvenile mortality
Population Growth effected by:• Abiotic Factors:
– Seasons can influence the life of short-lived organisms like insects.
Population Growth effected by:
• Food Supply:– If there is plenty of food the population increases,
if there is a loss of food the population decreases.
Population Growth effected by:
• Interspecific Competition:– Competition for resources among different species
of organisms.– Generally one species out competes the other.
Population Growth effected by:
• Predation:o If the population of the prey increases, the
predator will have more food and it will increase.
o The more prey will be eaten, so its population will decrease, so causing a cycle in both populations.
Population Growth effected by:
• Parasitism and Disease:o If the population of parasite increases, they
kill their hosts, so their population decreases. This means there are fewer hosts for the parasite, so their population decreases. This allows the host population to recover, so the parasite population also recovers.
