4-2 What Shapes an Ecosystem?

4-2 What Shapes an Ecosystem?
Photo Credit: ©Michael Fogden/DRK PHOTO Copyright Pearson Prentice Hall

Biotic and Abiotic Factors
Ecosystems are influenced by a combination of biological and physical factors. Biotic – biological factors Copyright Pearson Prentice Hall

Physical, or nonliving, factors that shape ecosystems are called abiotic factors. Abiotic factors include: temperature precipitation humidity wind nutrient availability soil type sunlight Copyright Pearson Prentice Hall

How do biotic and abiotic factors influence an ecosystem? Copyright Pearson Prentice Hall

The area where an organism lives is called its habitat. A habitat includes both biotic and abiotic factors. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall
The Niche The Niche A niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. No two species can share the same niche in the same habitat Copyright Pearson Prentice Hall

Community Interactions
What interactions occur within communities? Copyright Pearson Prentice Hall

Competition Competition occurs when organisms of the same or different species attempt to use an ecological resource in the same place at the same time. A resource is any necessity of life, such as water, nutrients, light, food, or space. Copyright Pearson Prentice Hall

Direct competition in nature often results in a winner and a loser—with the losing organism failing to survive. The competitive exclusion principle states that no two species can occupy the same niche in the same habitat at the same time. Copyright Pearson Prentice Hall

The distribution of these warblers avoids direct competition, because each species feeds in a different part of the tree. 18 12 Feeding height (m) Cape May Warbler Each of these warbler species has a different niche in its spruce tree habitat. By feeding in different areas of the tree, the birds avoid competing with one another for food. Bay-Breasted Warbler 6 Yellow-Rumped Warbler Copyright Pearson Prentice Hall

Predation An interaction in which one organism captures and feeds on another organism is called predation. The organism that does the killing and eating is called the predator, and the food organism is the prey. Copyright Pearson Prentice Hall

Symbiosis Any relationship in which two species live closely together is called symbiosis. Symbiotic relationships include: mutualism commensalism parasitism Copyright Pearson Prentice Hall

Mutualism: both species benefit from the relationship. Commensalism: one member of the association benefits and the other is neither helped nor harmed. Parasitism: one organism lives on or inside another organism and harms it. Copyright Pearson Prentice Hall

Ecological Succession
What is ecological succession? Copyright Pearson Prentice Hall

This series of predictable changes that occurs in a community over time is called ecological succession. Sometimes, an ecosystem changes in response to an abrupt disturbance. At other times, change occurs as a more gradual response to natural fluctuations in the environment. Copyright Pearson Prentice Hall

Primary Succession On land, succession that occurs on surfaces where no soil exists is called primary succession. For example, primary succession occurs on rock surfaces formed after volcanoes erupt. The first species to populate the area are called pioneer species. Copyright Pearson Prentice Hall

In this example, a volcanic eruption has destroyed the previous ecosystem. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. Copyright Pearson Prentice Hall

The first organisms to appear are lichens. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. Copyright Pearson Prentice Hall

Mosses soon appear, and grasses take root in the thin layer of soil. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. Copyright Pearson Prentice Hall

Eventually, tree seedlings and shrubs sprout among the plant community. Primary succession occurs on newly exposed surfaces, such as this newly deposited volcanic rock and ash. Copyright Pearson Prentice Hall

Secondary Succession Components of an ecosystem can be changed by natural events, such as fires. When the disturbance is over, community interactions tend to restore the ecosystem to its original condition through secondary succession. Copyright Pearson Prentice Hall

3–2 Energy Flow Copyright Pearson Prentice Hall

Where does the energy for life processes come from? Copyright Pearson Prentice Hall

Producers Without a constant input of energy, living systems cannot function. Sunlight is the main energy source for life on Earth. Copyright Pearson Prentice Hall

In a few ecosystems, some organisms obtain energy from a source other than sunlight. Some types of organisms rely on the energy stored in inorganic chemical compounds. Copyright Pearson Prentice Hall

Producers Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food. These organisms are called autotrophs. Because they make their own food, autotrophs are called producers. Copyright Pearson Prentice Hall

Producers Energy From the Sun The best-known autotrophs harness solar energy through a process known as photosynthesis. During photosynthesis, these autotrophs use light energy to convert carbon dioxide and water into oxygen and energy-rich carbohydrates. Copyright Pearson Prentice Hall

Photosynthesis is responsible for adding oxygen to—and removing carbon dioxide from—Earth's atmosphere. Sunlight is the main energy source for life on Earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Plants use the energy from sunlight to carry out the process of photosynthesis. Copyright Pearson Prentice Hall

Producers Life Without Light Some autotrophs can produce food in the absence of light. When organisms use chemical energy to produce carbohydrates, the process is called chemosynthesis. Copyright Pearson Prentice Hall

Producers Sunlight is the main energy source for life on Earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Other autotrophs, such as sulfur bacteria, use the energy stored in chemical bonds for chemosynthesis. In both cases, energy-rich carbohydrates are produced. Copyright Pearson Prentice Hall

Consumers Consumers Many organisms cannot harness energy directly from the physical environment. Organisms that rely on other organisms for their energy and food supply are called heterotrophs. Heterotrophs are also called consumers. Copyright Pearson Prentice Hall

There are many different types of heterotrophs. Herbivores eat plants. Carnivores eat animals. Omnivores eat both plants and animals. Detritivores feed on plant and animal remains and other dead matter. Decomposers, like bacteria and fungi, break down organic matter. Copyright Pearson Prentice Hall

Feeding Relationships
How does energy flow through living systems? Copyright Pearson Prentice Hall

Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Copyright Pearson Prentice Hall

Food Chains A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Copyright Pearson Prentice Hall

In some marine food chains, the producers are microscopic algae and the top carnivore is four steps removed from the producer. Food chains show the one-way flow of energy in an ecosystem. In this marine food chain, energy is passed from the producers (algae) to four different groups of consumers. Small Fish Zooplankton Squid Shark Algae Copyright Pearson Prentice Hall

Food Webs Ecologists describe a feeding relationship in an ecosystem that forms a network of complex interactions as a food web. A food web links all the food chains in an ecosystem together. Copyright Pearson Prentice Hall

This food web shows some of the feeding relationships in a salt-marsh community. This illustration of a food web shows some of the feeding relationships in a salt marsh. Copyright Pearson Prentice Hall

Trophic Levels Each step in a food chain or food web is called a trophic level. Producers make up the first trophic level. Consumers make up the second, third, or higher trophic levels. Each consumer depends on the trophic level below it for energy. Copyright Pearson Prentice Hall

Ecological Pyramids How efficient is the transfer of energy among organisms in an ecosystem? Copyright Pearson Prentice Hall

Ecological Pyramids Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level. Copyright Pearson Prentice Hall

Ecological Pyramids Ecological Pyramids The amount of energy or matter in an ecosystem can be represented by an ecological pyramid. An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. Copyright Pearson Prentice Hall

Ecological Pyramids Ecologists recognize three different types of ecological pyramids: energy pyramids biomass pyramids pyramids of numbers Copyright Pearson Prentice Hall

Ecological Pyramids 0.1% Third-level consumers Energy Pyramid: Shows the relative amount of energy available at each trophic level. Only part of the energy that is stored in one trophic level is passed on to the next level. 1% Second-level consumers 10% First-level consumers Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. 100% Producers Copyright Pearson Prentice Hall

Ecological Pyramids Biomass Pyramid: Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid. 50 grams of human tissue 500 grams of chicken 5000 grams of grass Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. Copyright Pearson Prentice Hall

Ecological Pyramids Pyramid of Numbers: Shows the relative number of individual organisms at each trophic level. Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. Copyright Pearson Prentice Hall

1. The main source of energy for life on Earth is a. organic chemical compounds. b. inorganic chemical compounds. c. sunlight. d. producers. Copyright Pearson Prentice Hall

2. Organisms that feed on plant and animal remains and other dead matter are a. detritivores. b. carnivores. c. herbivores. d. autotrophs. Copyright Pearson Prentice Hall

3. How does a food web differ from a food chain? a. A food web contains a single series of energy transfers. b. A food web links many food chains together. c. A food web has only one trophic level. d. A food web shows how energy passes from producer to consumer. Copyright Pearson Prentice Hall

4. In a biomass pyramid, the base of the pyramid represents the mass of a. heterotrophs. b. primary consumers. c. producers. d. top level carnivores. Copyright Pearson Prentice Hall

5. The amount of energy represented in each trophic level of consumers in an energy pyramid is about a. 10% of the level below it. b. 90% of the level below it. c. 10% more than the level below it. d. 90% more than the level below it. Copyright Pearson Prentice Hall

4-2 Which of the following is a biotic factor in a bullfrog's niche? water a heron climate day length Copyright Pearson Prentice Hall

4-2 An organism’s niche is different from its habitat because The niche does not include the place where the organism lives. the niche includes all the conditions under which the organism lives. the niche includes only abiotic factors. the niche includes only biotic factors. Copyright Pearson Prentice Hall

4-2 The attempt by organisms of the same or different species to use a resource at the same time in the same place is called competition. predation. symbiosis. cooperation. Copyright Pearson Prentice Hall

4-2 An association between two species in which one species benefits and the other is neither helped nor harmed is called symbiosis. mutualism. commensalism. parasitism. Copyright Pearson Prentice Hall

4-2 When a volcano erupts and completely destroys an ecosystem, the first species to populate the area are usually grasses and shrubs. pioneers such as lichens. small plants such as mosses. small animals such as rodents. Copyright Pearson Prentice Hall

4-2 What Shapes an Ecosystem?

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