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Visualizing Environmental Science How Ecosystems Work Chapter 5 Chapter Chapter77 [chapter [chapteropener openerimage] image] Copyright © 2014 John Wiley & Sons, Inc. All rights reserved. What is Ecology? • The study of the interactions among organisms and between organisms and their abiotic environment • Biotic and abiotic © 2014 John Wiley & Sons, Inc. All rights reserved. What is Ecology? • Levels of organization – Population: a group of organisms of the same species that live in the same place at the same time – Communities: all the populations of different species that live and interact together within an area at the same time; note the tidal pool community – Ecosystem: community and physical environment © 2014 John Wiley & Sons, Inc. All rights reserved. What is Ecology? • A landscape is a region that includes several interacting ecosystems • Biosphere– layer of Earth that contains all living organisms – Compare atmosphere, lithosphere , hydrosphere © 2014 John Wiley & Sons, Inc. All rights reserved. The Flow of Energy Through Ecosystems • Energy—the ability to do work – Potential energy—stored energy – Kinetic energy—energy of motion • Thermodynamics—the study of energy and its transformations – First and second law of thermodynamics © 2014 John Wiley & Sons, Inc. All rights reserved. The First Law of Thermodynamics • Energy cannot be created or destroyed • Total energy content always the same • Energy can change from one form to another – Photosynthesis—solar energy converted to chemical energy © 2014 John Wiley & Sons, Inc. All rights reserved. The Second Law of Thermodynamics • The amount of usable energy in the universe decreases over time as some is lost as heat – Heat—less usable and disorganized form of energy • Entropy—a measure of this disorder © 2014 John Wiley & Sons, Inc. All rights reserved. The Flow of Energy Through Ecosystems • Producers manufacture large organic molecules from simple inorganic molecules – Producers are potential food for other organisms – This moose is an herbivore or a primary consumer, feeding on the chemical energy stored in grasses © 2014 John Wiley & Sons, Inc. All rights reserved. The Flow of Energy Through Ecosystems • Consumers are animals that consume other organisms • Detritivores—consumers such as this crab eat organic matter called detritus • Decomposers—bacteria and fungi that break down dead and decaying organisms © 2014 John Wiley & Sons, Inc. All rights reserved. The Flow of Energy Through Ecosystems • Energy flow—the passage of energy in a one-way direction through an ecosystem, occurs in food chains • Trophic level—each level in a food chain • Energy is lost as heat along the way, thus the number of steps in a food chain is limited and less energy is available for organisms at the higher trophic levels © 2014 John Wiley & Sons, Inc. All rights reserved. The Flow of Energy Through Ecosystems • Ecological pyramids graphically represent the relative energy values of each trophic level • Pyramids of energy illustrate how energy dissipates into the environment as it moves from one trophic level to the next © 2014 John Wiley & Sons, Inc. All rights reserved. Ecosystem Productivity • Gross primary productivity (GPP) is the rate at which energy is captured during photosynthesis • Net primary productivity (NPP) is the amount of biomass found in excess of that broken down by a plant during cellular respiration – NPP is expressed in grams of dry matter per square meter per year for the selected ecosystems © 2014 John Wiley & Sons, Inc. All rights reserved. The Cycling of Matter in Ecosystems • Biogeochemical cycles – Matter—the material of which organisms are composed – Humans have GREAT influence on them © 2014 John Wiley & Sons, Inc. All rights reserved. The Cycling of Matter in Ecosystems • The carbon cycle – The global movement of carbon between the abiotic environment (atmosphere, ocean) and organisms – Atmosphere/ocean photosynthesis cellular respiration/combustion/decomposition atmosphere/ocean • Carbon is an essential component of organisms’ molecules • Also essential component of abiotic environment © 2014 John Wiley & Sons, Inc. All rights reserved. Carbon Cycle • 0.04% of the atmosphere • Needed to make proteins and carbohydrates • Present in several forms such as CO2, HCO3-, and CaCO3 • Fossil fuels, coal, oil and natural gas are deposits of carbon compounds • Photosynthesis fixes carbon from CO2 into carbohydrates © 2014 John Wiley & Sons, Inc. All rights reserved. The Hydrologic Cycle • Water circulates among the ocean, land, and atmosphere • Creates a renewable supply of water for terrestrial organisms – Runoff is water from land to rivers and lakes – Watersheds are areas of land where runoff drains © 2014 John Wiley & Sons, Inc. All rights reserved. The Nitrogen Cycle • Nitrogen is an essential component of proteins and nucleic acids • Atmosphere is 78% nitrogen gas • Five steps in which nitrogen cycles between the abiotic environment and organisms – – – – – Nitrogen fixation Nitrification Assimilation Ammonification Denitrification © 2014 John Wiley & Sons, Inc. All rights reserved. The Cycling of Matter in Ecosystems • Nitrogen-fixing bacteria carry out nitrogen fixation in soil and aquatic environments – This bacteria is fixing nitrogen in the nodules of a pea plant’s root • Photochemical smog and acid deposition are nitrogenbased air pollutants © 2014 John Wiley & Sons, Inc. All rights reserved. The Sulfur Cycle • Most sulfur is underground in sedimentary rocks and minerals • Animals get sulfur from plant protein • Sulfur gas is a minor part of the atmosphere, but movement of sulfur is substantial • Bacteria-driven cycle • Burning coal releases sulfur, which causes acid deposition © 2014 John Wiley & Sons, Inc. All rights reserved. The Phosphorous Cycle • No atmospheric component • Cycles between land and organisms • Phosphorous in soil is absorbed by plant roots – Necessary to make nucleic acids and ATP • Phosphorus in fertilizers can cause eutrophication, as in Lake Washington (chapter • opener) Anthropogenic loss of terrestrial phosphorus © 2014 John Wiley & Sons, Inc. All rights reserved. Ecological Niches • Niche – The totality of an organism’s adaptations, its use of resources, and the lifestyle to which it is fitted • Describes the place and function of an organism within the ecosystem • The “way of life of an organism” • Habitat – Part of an organism’s niche, the place where the organism lives © 2014 John Wiley & Sons, Inc. All rights reserved. Ecological Niches • Fundamental niche—the potential, idealized niche • Realized niche—the actual niche an organism occupies • While the fundamental niches of these two lizards initially overlap, the brown anole outcompeted the green anole, restricting is realized niche • Generalists vs. specialists © 2014 John Wiley & Sons, Inc. All rights reserved. Resource Partitioning • One way species avoid or reduce niche overlap • Serves to reduce competition for resources • Resource partitioning of five warbler species – Each species spends most of their time feeding in different portions of the tree © 2014 John Wiley & Sons, Inc. All rights reserved. Interactions Among Organisms • Symbiosis—two species living in close association • Symbiosis is the result of coevolution, as seen in this honeycreeper’s curved bill perfectly suited to sip nectar from the tubular flowers © 2014 John Wiley & Sons, Inc. All rights reserved. Interactions Among Organisms • There are three main types of symbiosis – Mutualism, where both organisms benefit • The ant obtains food and shelter from the plant and in turn, protects the plant from predators – Commensalism, where one benefits but the other is unaffected—neither harmed nor helped – Parasitism, one benefits at the expense of the other © 2014 John Wiley & Sons, Inc. All rights reserved. EnviroDiscovery Bee Colonies Under Threat • Since 2006, major losses to bee colonies, referred to as colony collapse disorder (CCD) – CCD is the result of pesticides, pathogens, parasites, and viruses such as Israeli acute-paralysis virus • Bees are important pollinators and many crops are threatened by bee declines – Pear trees in China being hand pollinated © 2014 John Wiley & Sons, Inc. All rights reserved. Interactions Among Organisms • Predation—the consumption of one species (prey) by another species (predator) – Coevolutionary “arms race” as predators evolve to better catch prey and prey evolve to better escape predator – The cheetah sprints at high speeds to catch prey – The goldenrod spider uses camouflage to ambush prey © 2014 John Wiley & Sons, Inc. All rights reserved. Avoiding Predation • Social behavior can decrease predation such as adult meerkats standing guard at their burrow, ready to alert the group of danger • Chemical defense in prey such as poison glands and bright warning colors • Camouflage to hide from predators such as this Indian leaf butterfly © 2014 John Wiley & Sons, Inc. All rights reserved. Competition • The interaction among organisms that vie for the same resources in an ecosystem, such as food or living space – Intraspecific competition – Interspecific competition © 2014 John Wiley & Sons, Inc. All rights reserved. Competition • Keystone species, such as the gray wolf, is crucial to the maintenance of the ecosystem – Not the most abundant, but have influence on entire ecosystem – Note the reintroduction of the wolf in 1995 affected the elk population © 2014 John Wiley & Sons, Inc. All rights reserved. Keystone Species • Another keystone species, the sea otter exerts their influence by changing competitive relationships. • They help maintain balance in an ecosystem. 3-31 Monterey Bay, California Keystone Species