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Interactions of Living Things 1 What is an Ecosystem • An ecosystem is made up of organisms interacting with one another and with non-living factors to form a working unit. – A frog eating an insect is an example of two living things interacting in an ecosystem. – A frog using a stream as shelter is an example of an interaction between a living thing and a nonliving part of an ecosystem 2 The study of the interactions between organisms and the living and nonliving components of their environment--ECOLOGY 3 Biosphere • Part of Earth where living things can life • Include: – – – – – – – – Deserts Mountains Rivers Prairies Wetlands Forests Plains Oceans 4 Ecology • Ecologists spend a lot of time outdoors, observing ecosystems up close. • They also conduct experiments in laboratories. 5 The Nonliving Environment • Abiotic factors- the nonliving parts of an organism’s environment. • Examples: air currents, temperature, humidity, light, pH, nitrogen availability, and soil. 6 The Nonliving Environment • Light and Temperature – determine where plants and animals can live • Air gases such as oxygen, nitrogen, and carbon dioxide are needed by most species • Soil types determine what plants and animals can live in an area; made of minerals, water, air, and organic matter 7 Abiotic Factors, cont. • Water – Some organsims are adapted for life in water – Water helps all living things carry out life processes, such as digestion – Water can also serve as shelter and a way to move from place to place •Sunlight – The sun is the main source of energy for most organisms on Earth – Energy from the sun is used by green plants to produce food – Humans get energy by eating plants and other organisms that have fed on plants 8 The Living Environment • Biotic factors- all the living organisms that inhabit an environment. • All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection. 9 Abiotic or Biotic? Biotic 10 Abiotic or Biotic? Abiotic 11 Abiotic or Biotic? Abiotic 12 Abiotic or Biotic? Biotic 13 Levels of Organization • Ecologists have organized the interactions in which an organism takes part into different levels according to complexity. • Ecologists organize living things into groups to make it easier to study ecosystems 14 1st Level of Organization • Organism: An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops 15 2nd Level of Organization • Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time. • Ecologists use tags to study populations of animals that travel long distances 16 2nd Level of Organization • Population: Ecologists want to know the size of a population, where its members live, and how it is able to stay alive • Ecologists determine population density by comparing the size of a population with its area 17 3rd Level of Organization • Biological Community: All the populations of different species that live in the same place at the same time and interact (solely biotic in terms of composition). 18 4th Level of Organization • Ecosystem: Populations of plants and animals that interact with each other in a given area, along with the abiotic components (physical and chemical) of that area. [terrestrial or aquatic] 19 5th Level of Organization • Biome: Many different ecosystems are found in a biome; e.g., mountains, tropical rain forests, tundra 20 6th Level of Organization • Biosphere: Broadest, most inclusive level, i.e., the thin volume of Earth and its atmosphere that supports life (5 to 6 miles above surface to deepest part of the oceans) •Earth:apple::biosphere:skin of apple 21 Energy Transfer •Begins with the SUN •Photosynthesis •Energy moves through a community as producers and consumers interact 6CO2 + 6H2O + sunlight & chlorophyll C6H12O6 + 6O2 23 Energy Transfer Energy moves through an ecosystem in the form of food Producers: autotrophs that capture energy and use it to make organic molecules *Photosynthesis *Chemosynthesis 24 Energy Transfer Consumers: heterotrophs that obtain energy by consuming organic molecules made by other organisms *Herbivores: eat producers *Carnivores: eat other consumers *Omnivores: eat both producers and consumers *Detritivores/Scavengers: feed on the “garbage” of an ecosystem Decomposer: Organisms that get energy by breaking down dead organisms 25 Living things use energy! Living things are divided groups by how they get their energy. – Producers: gets energy from sunlight – Consumers: gets energy from other things • Herbivore: eats only plants • Carnivore: eats only animals • Omnivore: eats plants and animals – Decomposers: get energy from dead things Living things use energy! • Food Chain - shows energy flow from one organism to another Food Chains and Food Webs Food Chain: single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer; matter cycle through food chains • The amount of matter on Earth never changes • Matter in ecosystem is recycled Food Web: Interrelated food chains that overlap in an ecosystem 28 Food Web 29 Food Chains and Food Webs Ecological pyramids: bottom layer of pyramid represents ecosystem producers; top layers represent consumers Energy pyramid: compares the energy available at each level of a food chain; bottom levels have more energy than top levels 31 Living things use energy! • Energy Pyramid – a triangular diagram that shows the loss of energy as it moves between organisms In an energy pyramid, a producer is ALWAYS on the bottom, with a predator on top. 90% of energy is used to stay alive while 10% is passed on (up the pyramid) Energy Pyramids Show •Amount of available energy decreases for higher consumers •Amount of available energy decreases down the food chain •It takes a large number of producers to support a small number of primary consumers •It takes a large number of primary consumers to support a small number of secondary consumers 33 Characteristics of Populations • Populations size: number of individuals in a population • Population density: number of individuals in a population that occupy a definite area – E.g., 100 mice per square kilometer • Population spacing: how organisms are arranged in an area – Evenly spaced: consistent distance between organisms Randomly spaced: individual location is independent of other individuals’ locations – Clumped spacing: organisms group together 34 Limiting Factors Ch.18-3 • Populations do not have enough resources to grow larger and larger forever • Any biotic or abiotic factor that limits the number of individuals, or size of a population – E.g. drought, food, water, living space • Carrying Capacity: the maximum population size that can live in an environment over time • Biotic Potential – the size a population could reach if no limiting factors stopped its growth 35 Organisms in a Changing Environment •Acclimation: Adjusting tolerance to abiotic factors over the course of a lifetime •Adaptation: Genetic change in a species or population that occurs from generation to generation over time 36 Symbiotic Relationships “Living together” – close interactions between species ~3 ways • The most common interactions in a community are FEEDING interactions • Organisms will compete for any resource that is in limited supply • The greater the population size of an area, the greater the competition for resources 37 Symbiotic Relationships “Living together” – close interactions between species ~3 ways 1. Mutualism: both species benefit Ex. Ants & acacia trees (ant protect trees, tree provides nectar & home) Ex: When the African tickbird eats insects off a zebra’s skin, both organisms in the relationship benefit 38 Symbiotic Relationships • 2. Commensalism: 1 species benefits & other is neither harmed nor benefits – Ex. Moss on trees (moss has place to grow, but does not effect trees) – A bird that builds its nest in a tree benefits but the tree in neither harmed nor helped 39 Symbiotic Relationships • 3. Parasitism: 1 species benefits, the other is HARMED – Ex. Tick on a dog (tick gets food, dog loses blood, could get a disease) – Insects biting a zebra’s skin harm the zebra but benefit themselves 40 Symbiotic Relationships • Predations is also one way in which population size is regulated – Predation is the act of one organism feeding on anotehr – Predators feed on prey • A bird of prey, such as a falcon, is an example of a predator • A falcon’s prey is the organism it eats 41 Habitat & Niche • Habitat is the place a plant or animal lives • Niche is an organism’s role in an ecosystem, to include the range of conditions that it can tolerate, the resources it uses, the methods by which it obtains resources, the number of offspring it has, the time of reproduction, etc. • Each type of organisms has a different role to play in an ecosystem 42