Ecology Chapters 2-5
Define ecology • Study of interactions among organisms and between organisms and their environment • Biosphere – all the parts of the planet in which life exists including land, ocean, and atmosphere • Interactions within biosphere create a web of interdependence between the organisms and their environment
Principles of Ecology The Biosphere
Principles of Ecology Biotic Factors • Living factors in an organism’s environment • Ex: predation Abiotic Factors • Nonliving factors in an organism’s environment • Ex: sunlight, temperature
Principles of Ecology Levels of Organization • Levels increase in complexity as the numbers and interactions between organisms increase. • organism • population • biological community • ecosystem • biome • biosphere
Principles of Ecology Organisms and Their Relationships • The lowest level of organization is the individual organism itself. • Organisms of a single species that share the same geographic location at the same time make up a population. • A biological community is a group of interacting populations that occupy the same geographic area at the same time.
Principles of Ecology • An ecosystem is a biological community and all of the abiotic factors that affect it. • A biome is a large group of ecosystems that share the same climate and have similar types of communities.
Principles of Ecology Ecosystem Interactions • A habitat is an area where an organism lives. • A niche is the role or position that an organism has in its environment.
Principles of Ecology Community Interactions • Competition • Occurs when more than one organism uses a resource at the same time • Predation • Many species get their food by eating other organisms.
Principles of Ecology Symbiotic Relationships • The close relationship that exists when two or more species live together • Mutualism • Both species benefit • Commensalism • One organism benefits, the other is not helped or harmed • Parasitism • One organism is helped, the other is harmed
Principles of Ecology • Organism that gets it energy requirements by consuming other organisms Energy in an Ecosystem • Autotrophs • Organism that collects energy from sunlight or inorganic substances to produce food • Heterotrophs A lynx is a heterotroph. • AKA: consumers • Types: • Herbivores: plant eaters • Carnivores: meat eaters • Omnivores: plant and meat eaters • Detritivores: eat plant and animal remains
Principles of Ecology • Detritivores eat fragments of dead matter in an ecosystem, and return nutrients to the soil, air, and water where the nutrients can be reused by organisms. Fungus
Principles of Ecology Models of Energy Flow • Food chains and food webs model the energy flow through an ecosystem. • Each step in a food chain or food web is called a trophic level.
How does energy flow through an ecosystem? • In one direction- from sun to producers then to consumers
Principles of Ecology Food Chains • A food chain is a simple model that shows how energy flows through an ecosystem.
Principles of Ecology Food Webs • A food web is a model representing the many interconnected food chains and pathways in which energy flows through a group of organisms.
Principles of Ecology Ecological Pyramids • A diagram that can show the relative amounts of energy, biomass, or numbers of organisms at each trophic level in an organism
What are trophic levels? • Trophic levels represent each step in a food chain • 1st level = producers • 2nd level = herbivores • 3rd level and up = carnivores and omnivores
How can we show all of the energy in an ecosystem? • Ecological pyramids – shows amounts of energy or matter within each trophic level • Energy pyramids – shows amounts of energy transferred to the next trophic level is only about 10% of the previous level • Biomass pyramid – shows total amount of living tissue • Numbers pyramid – shows #s of individuals in each trophic level
Principles of Ecology Cycling of Matter Cycles in the Biosphere • Energy is transformed into usable forms to support the functions of an ecosystem. • The cycling of nutrients in the biosphere involves both matter in living organisms and physical processes found in the environment such as weathering.
How does water move around an ecosystem? • The water cycle – water continually moves from the ocean to the atmosphere to the land and back to atmosphere • Evaporation – change from liquid to gas – from oceans or any standing water or lakes, etc. • Transpiration – evaporation from plant leaves • Condensation – gas to liquid in atmosphere forming clouds • Precipitation – liquid falls back to the earth where it drains into oceans, rivers, and lakes or soaks into the ground for storage • Run-Off- liquid runs back into water source • Percolation- liquid seeps into the soil.
Principles of Ecology The Water Cycle
Principles of Ecology • Approximately 90 percent of water vapor evaporates from oceans, lakes, and rivers; 10 percent evaporates from the surface of plants • Freshwater constitutes only about 3 percent of all water on Earth. • About 69 percent of all freshwater is found in ice caps and glaciers.
Principles of Ecology The Carbon and Oxygen Cycles
Principles of Ecology • Carbon and oxygen often make up molecules essential for life. • Carbon and oxygen recycle relatively quickly through living organisms.
Principles of Ecology The Nitrogen Cycle • The capture and conversion of nitrogen into a form that is useable by plants is called nitrogen fixation.
Principles of Ecology • Nitrogen enters the food web when plants absorb nitrogen compounds from soil. • Consumers get nitrogen by eating plants or animals that contain nitrogen.
Principles of Ecology • Nitrogen is returned to the soil in several ways: • Animals urinate. • Organisms die. • Organisms convert ammonia into nitrogen compounds. • Denitrification
Principles of Ecology The Phosphorus Cycle
Communities, Biomes, and Ecosystems Limiting Factors • Any abiotic factor or biotic factor that restricts the numbers, reproduction, or distribution of organisms is called a limiting factor. • Includes sunlight, climate, temperature, water, nutrients, fire, soil chemistry, and space, and other living things
Communities, Biomes, and Ecosystems Range of Tolerance • An upper limit and lower limit that define the conditions in which an organism can survive • The ability of any organism to survive when subjected to abiotic factors or biotic factors is called tolerance.
How do ecosystems change over time? • Always changing in response to natural and human disturbances • Older inhabitants die out, new organisms move in • Ecological succession – predictable changes in a community over time; the change in an ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors • Caused by slow changes in physical environment • Caused by sudden natural disturbance
Communities, Biomes, and Ecosystems Ecological Succession • There are two types of ecological succession—primary succession and secondary succession.
What is primary succession? • Succession on land where no soil previously existed • Hardened volcanic lava or ash • Rocks exposed from glacier melt • Pioneer species – 1st to populate an area • i.e. Lichens • Creates soil
What is secondary succession? • Follows a community changing disturbance • Wild fires, humans clearing land • Climax Communities – ending point of succession – mature stable community • Still goes through change over time
What role does climate play? • Weather – day to day atmospheric conditions at a certain place • Climate – average year-round conditions of temperature and precipitation • Causes of climate • Trapping of heat by atmosphere • Latitude • Transport of heat by winds and currents
What is the greenhouse effect? • Gases in the atmosphere trap heat energy and maintain Earth’s temperature range • Carbon dioxide, methane, water vapor • Traps heat being released from the earth • Naturally occurring • Magnified by the burning of fossil fuels
What effect does latitude have on climate? • Earth is tilted on it’s axis and receives varying angles of solar radiation at different latitudes. • Creates 3 climate zones: • Tropical: at the equator, hot • Temperate: middle latitudes, hot and cold depending on season • Polar: high latitudes, cold
Communities, Biomes, and Ecosystems • Biomes are classified by their plants, temperature, and precipitation.