• Ecology is the study of the interactions among organisms and their environment.

• Ecologists are scientists who study these relationships.

Ecology11

• Ecologists organize the environmental factors that influence organisms into two groups—nonliving and living or once-living.

• Abiotic (ay bi AH tihk) factors are the non-living parts of the environment.

Ecology11

• Living or once-living organisms in the environment are called biotic (bi AH tihk) factors.

• In any environment, birds, insects, and other living things, including humans, depend on one another for food and shelter.

• They also depend on the abiotic factors that surround them, such as water, sunlight, temperature, air, and soil.

Abiotic Factors11

• All living organisms need water to survive. • Water is an important part of the cytoplasm

in cells and the fluid that surrounds cells.

Water11

• Respiration, photosynthesis, digestion, and other important life processes can only occur in the presence of water.

• Salt water accounts for 97 percent of the water on Earth. It is found in the seas and oceans.

Water11

• The availability of sunlight is a major factor in determining where green plants and other photosynthetic organisms live.

Light and Temperature11

• By the process of photosynthesis, energy from the Sun is changed into chemical energy that is used for life process.

• Some areas of the world have a fairly consistent temperature year round, but other areas have seasons during which temperatures vary.

Light and Temperature11

• Water environments throughout the world also have widely varied temperatures.

• Air is composed of a mixture of gases including nitrogen, oxygen, and carbon dioxide.

Air11

• Polluted air can cause the species in an area to change, move, or die off.

• Most plants and animals depend on the gases in air for respiration.

• Clouds and weather occur in the bottom 8 km to 16 km of the atmosphere.

Air11

• All species are affected by the weather in the area where they live.

• Higher altitudes have less air pressure. Few organisms live at extreme air pressures.

• Soil type is determined by the amount of sand, silt, and clay it contains.

Soil11

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• Different plants need different kinds of soil.

Soil11

• Because the types of plants in an area help determine which other organisms can survive in that area, soil affects every organism in an environment.

• Organisms depend on other organisms for food, shelter, protection, and reproduction.

Biotic Factors11

• How organisms interact with one another and with abiotic factors can be described in an organized way.

• The living world is organized in levels. Levels of Organization11

• An organism is one individual from a population.

• All of the individuals of one species that live in the same area at the same time make up a population.

Levels of Organization11

• The populations of different species that interact in some way are called a community.

Levels of Organization11

• All of the communities in an area and the abiotic factors they interact with make up an ecosystem.

Levels of Organization11

• A biome is a large region with plants and animals well adapted to the soil and climate of the region.

Levels of Organization11

• The level of biological organization that is made up of all the ecosystems on Earth is the biosphere.

Levels of Organization11

• The biosphere includes the top part of Earth’s crust, all the waters that cover Earth’s surface, the surrounding atmosphere, and all biomes.

Levels of Organization11

Characteristics of Population—Population Size

• The number of individuals in the population is the population’s size.

• If a population is small and made up of organisms that do not move, the size can be determined by counting the individuals.

• Usually individuals are too widespread or move around too much to be counted. The population size then is estimated.

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Using the data table, create a double bar graph showing alligator births and deaths for four years.

Population Size22

Population Size

• The size of human population is increasing each year.

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• The size of a population is always changing. The rate of change in population size varies from population topopulation.

In year ____, the rabbit population reached its highest point.

What was the size of the rabbit population in that year?

How do you think the rabbit population affected the fox population over the same ten year period?

Population Size22

Predator-Prey InteractionsOn Isle Royale, an island in Lake Superior, the populations of wolves (the predator) and moose (the prey) rise and fall in cycles.

Population Size22

Population Density• The number of individuals in a population

that occupy a definite area is called population density.

• When more individuals live in a given amount of space the population is more dense.

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In the pond on the top, there are 10 flamingos in 8 square meters.

The population density is 1.25 flamingos per square meter.What is the population density of the flamingos in the pond on the bottom?

Population density is the number of individuals in an area of a specific size.Population density = # of individuals / unit area

Population Density22

Population Spacing

• Another characteristic of populations is spacing, or how the organisms are arranged in a given area.

• They can be evenly spaced, randomly spaced, or clumped together.

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Limiting Factors

• All ecosystems have a limited amount of food, water, living space, mates, nesting sites, and other resources.

• A limiting factor is any biotic or abiotic factor that limits the number of individuals in a population.

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Limiting Factors• Competition is the struggle among organisms

to obtain the same resources needed to survive and reproduce.

• As population density increases, so does competition among individuals for the resources in their environment.

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Carrying Capacity

• Carrying capacity is the largest number of individuals of a species that an environment can support and maintain for a long period of time.

• If a population gets bigger than the carrying capacity of the environment, some individuals are left without adequate resources.

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Biotic Potential• The maximum rate at which a population

increases when plenty of food and water are available, the weather is ideal, and no diseases or enemies exist, is its biotic potential.

• Most populations never reach their biotic potential, or they do so for only a short period of time.

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• Eventually, the carrying capacity of the environment is reached and the population stops increasing.

Symbiosis – Close interaction between species

• Mutualism – When both species benefit from the relationship

• Commensalism – a form of symbiosis that helps one species but has not effect on the other.

• Examples – Moss growing on trees, cattle egrets and livestock

• Parasitism – When one species is harmed and the other benefits

• Examples – Dog and fleas

• Predation – when one species hunts, kills and eats another

• Habitat - Where an organism lives

• Niche - an organism's function in its ecosystem

Energy – moves through a community as producers and consumers interact

Food Chain – How food energy moves from one organism to another

Food webs – Overlapping food chains to better show the way energy moves through an ecosystem

• Ecological Pyramids- bottom layers of pyramid represents ecosystem producers; top layers represent consumers

• Energy Pyramids – compares the energy available at each level of a food chain; bottom levels have more energy than the top levels

• Cycles of Matter – matter that makes up living organisms, such as water, carbon, and nitrogen, are recycled through the environment.

• Process of evaporation, condensation, and precipitation make up the water cycle.

• Carbon, nitrogen, phosphorus, sulfur, and other elements needed by living organisms move through Earths biosphere

The Cycles of Matter

• The law of conservation of mass states that matter on Earth is never lost or gained. It is used over and over again.

• The carbon atoms in your body might have been on Earth since the planet formed billions of years ago. They have been recycled billions of times.

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Water Cycle• The water cycle involves the process of

evaporation, condensation, and precipitation.

• Heat from the Sun causes water on Earth’s surface to evaporate, or change from a liquid to a gas, and rise into the atmosphere as water vapor.

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Water Cycle• Eventually, the water vapor changes back

into tiny droplets of water.

• It condenses, or changes from a gas to a liquid.

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• When the droplets become large and heavy enough, they fall back to Earth as rain or other precipitation.

Other Cycles in Nature33

• The movement of carbon through Earth’sbiosphere is called the carbon cycle.

Other Cycles in Nature• The nitrogen cycle begins with the transfer

of nitrogen from the atmosphere to producers then to consumers.

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• The nitrogen then moves back to the atmosphere or directly into producers again.

• Phosphorus, sulfur, and other elements needed by living organisms also are used and returned to the environment.