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Ecology Outlines
I. Living Earth
A. Biosphere—the part of Earth that supports life
1. The top portion of Earth’s crust, all the waters on Earth’s surface, and the surrounding atmosphere
2. Made up of different environments that are home to different kinds of organisms
B. Ecosystem—all the organisms living in an area and the nonliving features of their environment
1. Ecology is the study of interactions that occur among organisms and their environment.
2. A population is made up of all the organisms in an ecosystem that belong to the same species.
3. A community is all the populations in an ecosystem.
C. Habitat—the place in which an organism lives
1. Must provide the kinds of food, shelter, temperature, and moisture the organism needs to survive
2. Example: trees are the woodpecker’s habitat
II. Abiotic Factors
A. Living or once-living environmental features are called biotic factors; abiotic factors are nonliving physical features.
B. Atmosphere—the air that surrounds Earth
C. Water—the major ingredient of the fluid inside the cells of all organisms
D. Soil—a mixture of mineral and rock particles, the remains of dead organisms, water, and air
E. Sunlight—the source of energy for most life on Earth
F. Most organisms’ body temperatures should stay within the range of 0°C to 50°C for survival.
1. Temperature is affected by latitude; areas closer to the equator are warmer than areas farther from the equator.
2. Elevation—distance above sea level that affects temperature, wind, and soil
G. Climate—an area’s average weather conditions over time, including
temperature, precipitation, and wind
1. For most living things, temperature and precipitation are the two most important components of climate.
2. Heat energy from the Sun creates air currents called wind.
III. Populations
A. Competition—two or more organisms seek the same resource at the same time
1. Competition for food, living space, or other resources can limit the population.
2. Competition is usually most intense between members of the same species.
B. Population size—indicates whether a population is healthy and growing
1. Population density—the size of a population that occupies a specific area
2. Two ways to measure the size of a wildlife population
a. Trap-mark-release method
b. Sample count method
3. Elements that affect population size
a. Limiting factor—any living or nonliving feature that restricts the number of individuals in a population
b. Carrying capacity—the largest number of individuals of one species that an ecosystem can support
c. Biotic potential—the maximum number of offspring that parent organisms can produce
d. Birth and death rates
e. Movement of organisms into or out of an area
C. Exponential growth—the larger a population becomes, the faster it grows
ESSENTIAL QUESTION:
If a population were decreasing, what kinds of questions would an ecologist ask to determine the problem?
1. Are there any limiting factors?
2. Are there enough food, water, living space, and mates available?
3. Has the population reached its carrying capacity? Does the population have a low biotic
potential?
4. Is something causing the death rate to increase, or the birth rate to decrease?
5. Are organisms moving out of the area?
IV. Interactions Within Communities
A. Sun—source of energy that fuels most life on Earth
1. Producers/Autotrophs—organisms that use an outside energy source to make energy-rich molecules
a. Most producers use the Sun and contain chlorophyll, a chemical required for photosynthesis.
b. Some producers, found near volcanic vents on the ocean floor, use mineral molecules as energy sources for chemosynthesis.
2. Consumers/Heterotrophs—organisms that cannot make their own energy-rich molecules: they obtain energy by eating other organisms.
a. Herbivores, like deer and rabbits, eat plants.
b. Carnivores, like frogs and lions, eat animals.
c. Omnivores, like pigs and humans, eat both plants and animals
d. Decomposers, like earthworms and bacteria, eat dead organisms
3. Food chain—a model that shows the feeding relationships among the organisms in an ecosystem
Content B. Symbiosis—any close relationship between species
1. Mutualism—a symbiotic relationship in which both species benefit
2. Commensalism—a symbiotic relationship in which one organism benefits and the other is not affected
3. Parasitism—a symbiotic relationship in which one organism benefits and the other is harmed
C. Niche—a species’ unique requirements for survival, including its habitat and food and how it avoids danger, finds a mate and cares for its young
1. Predator and prey
a. Predator—consumer that captures and eats other consumers
b. Prey—the organism that is eaten
c. Predators limit the size of prey populations, increasing the number of different species that can live in an ecosystem
2. Cooperative actions improve a species’ survival.
a. Example: one deer warns the others of predators in the area.
b. Example: individual ants perform different tasks required for the survival of all.
ESSENTIAL QUESTION:
Are humans producers or consumers? Explain.
Humans are consumers because we cannot produce our own energy-rich molecules (food). We must obtain it by eating other organisms, which have energy-rich
molecules.
V. Energy Flow
A. Matter can be recycled over and over again, but energy is converted from one form to another.
1. During photosynthesis, producers convert light energy to chemical energy.
2. Chemosynthesis—the production of energy-rich nutrient molecule from chemicals.
B. Energy stored in the molecules of one organism is transferred to another when one organism becomes food for another organism.
1. Food chains—a simple way of showing how matter and energy pass from one organism to another
2. Food web—shows all the possible feeding relationships among the organisms in a community
C. Energy pyramid—shows the amount of energy available at each feeding level in an ecosystem
ESSENTIAL QUESTION:
What two processes do producers use to convert abiotic factors to energy?
Photosynthesis and chemosynthesis
VI. Cycles in Nature
A. Earth’s biosphere contains a fixed amount of water, carbon, nitrogen, oxygen, and other materials that cycle through the environment and are
reused by different organisms.
B. Water cycle—how water moves from the Earth’s surface to the atmosphere and back to the surface again
1. Evaporation—when liquid water changes into water vapor and enters the atmosphere (Transpiration)
2. Condensation—the process of changing water from a gas to a liquid
3. When water drops become large and heavy enough, they fall to the ground as rain or other precipitation.
C. Nitrogen cycle—the transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere
1. Nitrogen fixation—a process in which some types of soil bacteria can form the nitrogen compounds that plants need
2. Farmers replace nitrogen in the soil by growing nitrogen-fixing crops or using fertilizers that contain nitrogen compounds that
plants need for growth.
D. Carbon cycle—how carbon molecules move between the living and nonliving world
1. Producers remove carbon dioxide gas from the air during photosynthesis.
2. Respiration—the chemical process that provides energy for cells
ESSENTIAL QUESTION:
List four processes in the water cycle.
Transpiration, evaporation, condensation, and precipitation
Ecosystems
VII. How Ecosystems Change
A. Ecological succession—normal, gradual changes that occur in the types of species that live in an area
1. Primary succession begins in a place without soil.
a. Starts with pioneer species such as lichens, that can grow on rock
b. New soil forms as weather and erosion break down rock.
c. Decaying plants add organic material to new soil.
2. Secondary succession begins in a place that has soil and once had living organisms
a. Example: after a fire or removal of buildings
b. Occurs faster and has different pioneer species than primary succession
B. Climax community—stable stage of ecological diversity and balance
ESSENTIAL QUESTION:
Why does primary succession take longer than secondary succession?
New soil has to form from rock and organic material.
VIII. Biomes
A. Factors that affect biomes climate
1. temperature
2. precipitation
B. Major biomes—large areas with similar climates and ecosystems
1. tundra—cold, dry, treeless region
a. Permanently frozen soil called permafrost
b. Average temperature: –12°C
c. Average precipitation is less than 25 cm per year.
d. Plants: mosses, grasses, small shrubs, lichens
e. Animals: insects, ducks, geese, other birds, mice, arctic hares, reindeer
2. Taiga—cold forest of mostly evergreen trees
a. Soil thaws in the short summer.
b. Precipitation: mostly snow, 35 cm– 100 cm per year
3. Temperate deciduous forests—region with four seasons, mostly trees that lose their leaves in autumn
a. Temperatures range from below freezing in winter to 30°C or more in summer.
b. Precipitation: throughout the year, 75 cm–150 cm per year
4. Temperate rain forest—tall trees with needlelike leaves
a. Average temperature: 9°C–12°C
b. Precipitation: 200 cm–400 cm per year
5. Tropical rain forests—the most biologically diverse of all biomes
a. Average temperature: 25°C
b. Precipitation: 200 cm–600 cm per year
c. Four zones: forest floor, understory, canopy, emergents
d. Human impact: Habitats being destroyed by farmers and loggers
6. Desert—driest biome, supports little plant life
a. Temperatures: vary from hot to cold
b. Precipitation: less than 25 cm per year
c. Soil: thin, sandy, or gravelly
d. Plant: cactus
e. Animal: kangaroo rat
7. Grasslands—prairies or plains, dominated by grasses
a. Temperatures: temperate or tropical
b. Precipitation 25 cm–75 cm per year; dry season
ESSENTIAL QUESTION:
What temperature ranges and precipitation levels support the greatest diversity of plants and
animals?
Those of tropical rain forests—average daily temperature is 25° C and evenly distributed
rainfall is 200 cm to 600 cm annually.
IX. Aquatic Ecosystems
A. Freshwater ecosystems—include flowing and standing water, low or no salt
1. Rivers and streams—flowing water
a. Most nutrients washed into water from land.
b. The faster the flow, the greater the oxygen content.
2. Lakes and ponds—very little flow
a. Sunlight warms and lights pond bottom, supporting plant and animal life.
b. Deeper lakes support life along shallow shoreline or surface.
3. Water pollution—a problem caused by fertilizer-filled runoff and sewage
4. Wetlands—regions wet all or most of year
a. Lie between solid land and water
b. Very fertile ecosystems
B. Salt water ecosystems—95% of Earth’s water contains high concentration of salt, or high salinity.
1. Open oceans—divided into lighted and dark life zones
a. lighted—upper 200 m and home of plankton
b. dark—below 200 m where animals feed on material that floats down or prey on each other
2. Coral reefs—diverse and fragile ecosystems formed from coral shells of calcium carbonate
3. Seashores (Coastal)—along coastlines
a. Intertidal zone—covered with water at high tide and exposed to air at low tide
b. Drastic changes in temperature, moisture, salinity, and wave action
4. Estuaries—where a river meets an ocean; called bays, lagoons, harbors, inlets, sounds
a. Rich in nutrients
b. Changing mixture of salt water and freshwater