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Biology I Mr. Salvitti Name: Per/Date: Skill Builder #5: Introduction to Ecology I. Background: The Sixth Mass Extinction: As the human population has increased, many other species have declined in number or became extinct. For example, on the Hawaiian Islands, where isolation fostered the evolution of a diverse and unique set of species, 60 of the 100 species of native birds have disappeared since the first human colonists arrived. They were eliminated by habitat destruction, overhunting, and introduced diseases and predators. Worldwide, about 20 percent of the species of birds have become extinct in the last 2,000 years. Today extinction is occurring most rapidly in the tropics. Paleontologists have found evidence in the fossil record of five major mass extinctions, episodes in which a large percentage of Earth’s species became extinct in a relatively short time. The five extinctions of the past, where a result of natural biologic and climatic causes. The sixth mass extinction which is happening now is a result of human activities on the planet. Currently, species are disappearing faster than at any time since the last mass extinction—the disappearance of the dinosaurs 65 million years ago. Scientists estimate that about one-fifth of the species in the world may disappear in just this next century. Ecology is the study of the interactions between organisms and the living (biotic) and nonliving (abiotic) components of their environment. The Earth includes a tremendous variety of living things. Each organism depends in some way on other living and nonliving things in its environment. Ecology involves collecting information about organisms and their environments, looking for patterns, and seeking to explain these patterns. Today’s Environment: Although the field of ecology was not named until 1866, ecological information and understanding have always been crucial to humans and our survival. Before the development of agriculture about 10,000-12,000 years ago, our ancestors obtained all of their food by hunting and gathering grains, seeds, berries, nuts, roots, and plants. For them survival depended on practical knowledge about the environment. While our understanding of the environment has grown much more sophisticated, our need for information has grown more urgent. Over the past few decades, humans have changed the environment on a greater scale than ever before in history. Learning how to improve our effect on the environment is critical to the survival of our species and the planet. The biosphere is the portion of Earth that supports life. It includes our atmosphere (air), lithosphere (landmasses), hydrosphere (bodies of freshwater and saltwater), and locations below the Earth’s surface that supports life. Biotic Factors are all of the living things in an organism’s environment. Abiotic Factors include all of the nonliving things in an organism’s environment. Examples are temperature, air currents, sunlight, rainfall, soil type and available nutrients. No single organism is isolated!! The interconnectedness or interdependence of all organisms is central to the study of ecology. The survival of organisms depends on their interactions with their surrounding environment Example: Humans cannot live without the plants that produce food and oxygen. Biosphere: is the broadest and most inclusive level of organization. The Earth and its atmosphere make up our biosphere. It extends from 8 to 10 km (5-6 miles) above the Earth’s surface, to the deepest parts of the ocean. The biosphere is comprised of smaller units called ecosystems. Ecosystems: include all of the organisms, and the abiotic environment found in a specific place. Example: pond ecosystem-- Abiotic components: water temperature (Temp.), amount of dissolved oxygen (D.O.) and carbon dioxide (CO2), the pH level (acid or basic, 0-14). Biotic components: insects, fish, algae, aquatic plants, turtles. Some ecosystems can also be considered a habitat of an organism. A niche, is the role an organism plays in its environment. It includes: Range of conditions the organism can tolerate; Methods by which it obtains resources; and interactions with its environment such as reproduction. 1 Biology I Mr. Salvitti Name: Per/Date: A community is all of the interacting organisms living in an area. Examples: All of the fish, turtles, insects, plants and algae make up the community of a pond. Competition occurs when more than one organism uses a resource at the same time. Ex: Lions and hyenas compete for the same food sources. Predation is the act of one organism consuming another for food. Most species survive because of relationships called symbiosis—a close and often long-term interaction between two or more different biological species. Examples: Mutualism: is when both organisms benefit. Ex: The Egyptian plover takes insects from the backs of buffaloes, giraffes and rhinos. Commensalism: One benefits; the other is not affected. Ex: Sea anemone and the clown fish. Parasitism: One benefits at the expense of the other. Ex: Deer tick and mammal. Energy in an Ecosystem: Ecosystems are most often thought of or measured in terms of energy production and energy flow. In an ecosystem the ultimate source of energy is the sun. Autotrophs: Are primary producers that make their own food. They use energy from sunlight or inorganic substances. They are the foundation of all ecosystems, and they make energy available for all of the other organisms to use. Ex: Plants. Heterotrophs: on the other hand, get their energy by consuming other organisms. They are referred to as “consumers.” Herbivores eat only plants or herbaceous food. Example: Deer. Carnivores eat other animals or meat. Example: Lions. Omnivores eat both plants and animals, and most anything they can find. Examples: bears and raccoons. Detrivores eat dead/decaying material. Example: Earth worms. Decomposers are similar to detrivores break down dead organisms by releasing digestive enzymes. Ex: fungi such as mushrooms. Decomposers are important because they make nutrients available for all other organisms. Trophic levels: Each step in a food chain or food web is referred to as a trophic level (food or feeding level). Autotrophs are the first trophic level in ALL food chains and food webs and are considered primary producers. Primary producers: make their own food. Plants are considered primary producers. Primary consumers: eat the primary producers. Secondary consumers: eat the primary consumers. Third-level consumers: eat the secondary consumers. Energy flows upward from the primary consumer to the third level consumer. Since primary consumers are considered the foundation of food webs and chains there are more of them than any other trophic level above. As the levels go up each level have less numbers of individuals and less energy to pass on. Food chains: are a simple model that shows how energy flows through an ecosystem. Arrows show one-way energy flow in the chain or system. Each organism uses some of the energy from the organism it eats. The remaining energy is lost to the surrounding environment. Food webs: are models that represent the interconnected food chains in which energy flows through a group of organisms. An ecological pyramid: is diagrams that show the relative amounts of energy, biomass or numbers of organisms at each trophic level. Biomass is the total mass of living matter at each trophic level. This includes all the plants and animals that live there. Approximately 90% of all energy at a tropic level is NOT transferred to the level above it. II. Identification: 1. Levels of Organization 2. An Ecosystem 2 Biology I Mr. Salvitti 3. A community Name: Per/Date: 4. Mutualism Birds 5. Food Chains 6. Food Web 7. Energy Pyramid 3 Biology I Mr. Salvitti Name: Per/Date: III. Assessment: 1. The first mass extinction occurred during the Ordovician Period around 490 millian years ago, followed by the Devonian Pd 417 mya, then the Permian Pd 290 mya, followed by the Triassic Pd 245 mya, and then the Cretaceous Pd 144 mya. When did the last mass extinction occur? Why? _________________________ _______________________________________________________________________________________ 2. What is the science of ecology? ___________________________________________________________ _______________________________________________________________________________________ 3. The Biosphere includes: _________________________________________________________________ _______________________________________________________________________________________ 4. What is the diffedence between biotic and abiotic? ____________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ 5. When a farmer measures the pH of the soil before planting a crop of soy beans which type of factor is he analyzing boitic or abiotic? ________________________________________________________________ 6. When more than one organism uses a resource at the same time such as lions and hyenas competing for the same food biologist refer to this as: _______________________________________________________ 7. Decomposers are important because: _______________________________________________________ _______________________________________________________________________________________ 8. The ultimate energy source in an ecosystem is: _______________________________________________ _______________________________________________________________________________________ 9. What biotic factor is considered to be the foundation of an ecosystem in terms of energy flow? Explain. _ _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ 10. CRITICAL THINKING: Based on your limited understanding of ecology and the biosphere, why is it important for high school students in Pennsylvania to study the effects that global warming has on the loss of Polar Bears in the Arctic, or the disappearance of amphibians in South America? ___________________ ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ 4