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PRINCIPLES OF ECOLOGY Chapter 2 Introduction: What is Ecology? 2 The scientific study of interactions among organisms and their environments Shows relationships between living and nonliving parts of the world Scientists obtain data through observation and controlled experiments Aspects of Ecological Study 3 Biosphere = the portion of Earth that supports life Interactions between living and non-living things Abiotic factors = nonliving parts of the environment Determine (deserts, grassland, forest, tropical forest, tundra, freshwater, saltwater) Ex: which species live in a particular environment air currents, temperature, moisture/water, light, soil Biotic factors = living parts of the environment All living organisms affect other organisms (food, shelter, reproduction & protection) Ex: plants, animals, decomposers Levels of Organization 4 Scientists study interactions among organisms at different levels: 1. Organism – one species A zebra What does it need to survive? 2. Population – a group of the same species A herd of zebras Competition for resources Levels of Organization, cont. 5 3. Community –interacting populations in an area zebras, giraffes, lions, trees, grass changes in one population affect the other populations 4. Ecosystem – interactions between the community and nonliving surroundings African grassland Three major kinds of ecosystems: Terrestrial = land Freshwater = ponds, lakes, streams Saltwater (marine) = oceans 5. Biome 6. Biosphere Organisms in an Ecosystem 6 Habitat = the place where an organism lives Several species may share one habitat Niche = the role and position a species has in its environment – how it survives & reproduces Unique strategies for finding food & shelter Example: bird beaks – adapted for different foods or feeding strategies Beak Variations in Finches 7 Biodiversity 8 the number of different species that live in a certain area How Organisms Get Energy 9 All organisms need energy to survive Autotroph Two types of Organisms 10 Autotrophs – use energy from the sun (photosynthesis) or chemicals (chemosynthesis) to produce their own food Also called producers – they produce usable energy Examples: plants, some bacteria Heterotrophs – organisms that must eat to obtain energy Also called consumers – they must consume food to get usable energy Examples: all animals, some bacteria, decomposers Kinds of Heterotrophs 11 Herbivores – feed on autotrophs such as plants, seeds, or algae Insects, deer, rabbits, squirrels, bees, elephants Carnivores – feed on other heterotrophs Lions, coyotes, sharks Scavengers eat carrion & refuse (leftovers from carnivores) Ants, beatles, vultures Kinds of Heterotrophs 12 Omnivores – feed on animal and plant materials Humans, raccoons, opossums, bears Decomposers – break down dead organisms & recycle nutrients Fungi & bacteria Matter & Energy Flow in Ecosystems 13 The food you eat contains matter (carbon, nitrogen, oxygen, hydrogen, etc) and energy Energy moves ONE WAY – it cannot be recycled Food chains – simple models used to show the movement of energy through an ecosystem Food Chains 14 Energy moves from autotrophs to heterotrophs, eventually to decomposers Arrows indicate the direction of energy transfer Example: Algae fish bird The algae is an autotroph. Energy is transferred to the fish when it eats the algae, then to the blue heron when it eats the fish Most food chains have no more than five links because the amount of energy decreases at each level. Trophic Levels 15 Represent a feeding step in the passage of energy Many species may occupy one trophic level Food webs express all the possible feeding relationships at each level in a community More realistic than a food chain because most organisms depend on more than one food source Food webs represent a network of food chains – overlapping & interconnected Sample Food Web: 16 3rd order heterotrophs 2nd order heterotrophs 1st order heterotrophs Autotrophs Ecological Pyramids 17 Food chains, food webs, and ecological pyramids show how energy moves in only ONE direction through an ecosystem 10% rule – only about ten percent of the energy at one trophic level is passed on to the next (the rest is used for life processes) Types of Pyramids: Energy Pyramid Pyramid of Numbers Biomass Pyramid Energy Pyramid 18 Nutrients in the Biosphere Nutrients differ from energy in two ways: It is not lost after being used, it will not produces a product such as heat for the environment Passes from one organism to another in a continues cycle that has no beginning or end Water Cycle Consists of three process: Evaporation Condensation Precipitation Nitrogen Cycle Nitrogen fixation – convents atmosphere N2 to ammonium (NH4) and nitrate (NO3) Autotrophs will absorb and convert to organic materials Heterotrophs will consume in foods Carbon Cycle Autotrophs uses CO2 gases from the atmosphere to use in photosynthesis Nonphotosynthetic organism give off CO2 COMMUNITIES & BIOMES Chapter 3 Living in a Community 24 Limiting Factors Environmental factors that affect an organism’s ability to survive Any biotic or abiotic factor that restricts the existence, population, reproduction, or distribution Food, predators, competing species, temperature, rainfall, light, soil Changes in one population may affect others in the community Ranges of Tolerance 25 Tolerance = the ability of an organism to withstand changes in biotic & abiotic factors Organisms must stay within their tolerance range Examples: people and temperature; plants & water May affect population size Succession: changes over time 26 Succession = the orderly, natural changes and species replacements that take place in the communities of an ecosystem Occurs in stages May take centuries Two types: Primary Succession Secondary Succession Primary Succession 27 The colonization of new sites Avalanche, volcano eruption, volcanic island Pioneer species = first species in an area Lichen grows on rocks, breaking them down and producing soil Climax community = a stable, mature community that undergoes little or no change in species Secondary Succession 28 The sequence of community changes that takes place after a community is disrupted Natural disasters (hurricane, fire), human actions Occurs in areas that previously contained life Takes less time than primary succession Biomes 29 Is a major type of ecosystem with its own temperature ranges, rainfall amounts, and types of organisms Aquatic Biomes 30 Marine (Salt Water) Location: Oceans, Estuaries, Photic Zone (with light), & Aphotic Zone (without light) Types of Organisms: Kelp, Whales, Dolphins, Sharks, Tuna, Crabs, Shrimp, Lobsters, Salmon, Eels, Plankton Freshwater Location: Wetlands, Rivers, Streams, Ponds, Lakes, & Creeks Types of Organisms: Algae, Muskrats, Ducks, Geese, Fish, Pike, Carp, Bass, & Catfish Land Biomes 31 Tundra Taiga Temperate Forest Grassland Desert Tropical Rain Forest POPULATION BIOLOGY Chapter 4 Population Growth Population Growth = an increase in the size of a population over time Populations grow exponentially The rate increases because the total number of reproducing individuals is increasing As the population grows larger, it reproduces faster Patterns of population growth Depend on environmental conditions Example: Elephants vs. mosquitoes Stages of Population Growth 1. 2. 3. 4. 5. Beginning growth 4 Rapid growth 3 Leveling off Carrying capacity Fluctuations 2 1 5 Limits to Population Growth (abiotic) Populations cannot grow indefinitely Carrying Capacity = the number of organisms that an environment can support Two kinds of limiting factors: Density-dependent factors disease, competion, parasites, food Bigger influence if population is large Density-independent Temperature, factors storms, floods, drought, habitat disruption Affect all populations Limits to Population Growth (biotic) Predation Predators usually catch and eat the young, old, sick, or injured individuals of a population Competition When population numbers are large, organisms must compete for resources when the demand exceeds the supply, the population decreases Crowding & Stress Individuals may become more aggressive, decreased parental care, decreased fertility, decreased resistance to disease As a result, the population decreases Symbiosis Other interaction between species Occurs when two species live in close contact with each other for a long period of time Host – is the species that is being used Symbiot – is the species that is acting on the host Symbiosis Mutualism Both individuals benefit from each other ++ Communalism One benefits the other is not affected +0 Parasitism One benefits the other is harmed + -- Amensalism One will stop the growth of another without being affected by it 0 -- Human Populations Demography (demographics) = study of human populations Several factors affect human population: Birth rates Death rates Age structure – helps to predict if a population is growing rapidly Immigration – movement into a population Emmigration – movement out of a population Age structure Demographers collect data on age structures of different countries Tracking data allows scientists to make predictions about population growth BIOLOGICAL DIVERSITY & CONSERVATION Chapter 5 Biological Diversity Biodiversity = the variety of life in an area The number of species that live in a certain area Terrestrial biodiversity increases as you move closer to the equator Canada = 163 mammal species United States = 367 Mexico = 439 The greatest biodiversity is found in warm areas such as tropical rain forests and coral reefs Larger islands have more biodiversity than smaller islands with the same climate Importance of biodiversity Organisms are adapted to live together in communities If one species is lost, it affects the populations of other species Life depends on life Animals cannot exist without plants Many plants cannot exist without the animals that pollinated them Decomposers recycle nutrients and get rid of dead and decaying material Biodiversity brings stability to an ecosystem A pest or parasite may destroy a farm, but not a forest. Importance to people Humans depend on other organisms Oxygen supplied by plants Diversity of foods to eat Biodiversity is useful to humans Making new food crops Improving people’s health Loss of biodiversity Extinction = the disappearance of a species when the last of its members dies Almost 40 species of plants and animals in the United States have gone extinct since 1980 Threatened = When the population of a species begins to decline rapidly Ex. African elephants have decreased in number due to hunting Endangered = when a species’ numbers become so low that extinction is possible Ex. California condor, Florida manatees, bald eagle, Sumatran tiger, Galapagos tortoise, etc. Threats to Biodiversity Complex interactions among species make ecosystems unique and species well adapted to their habitats Changes to habitats put organisms in danger of extinction Most common threats to biodiversity Habitat loss Damage to habitats Pollution Introduction of exotic species Habitat Changes The biggest threat to biodiversity is habitat loss Habitat fragmentation = the separation of wilderness areas from other wilderness areas Ex. Building a freeway, clear-cutting forest trees, etc. Habitat degradation = damage to a habitat by pollution Air pollution Water pollution Strategies of Conservation Biology Conservation Biology is a new field that implements plans and methods to protect biodiversity Resource conservation Conservation biologists study law, politics, sociology, economics, and ecology Legal Protection of Species President Nixon signed the US Endangered Species Act into law in 1973. It is illegal to harm any species on the endangered or threatened species list. Federal agencies cannot fund any project that would harm these animals Cannot change an ecosystem where endangered or threatened species live Other countries have established similar laws International trade is controlled regarding certain species Preserving habitats National Parks & Preserves Protecting whole communities and ecosystems is the best way to protect the organisms that live there. Ex. Yellowstone, Yosemite, etc Park rangers are hired to manage the parks and ensure protection of organisms Sustainable use = allowing people to use the resources without damaging the ecosystem Habitat corridors = natural strips that allow the migration of organisms from one area to another Prevents isolation and habitat fragmentation Reintroduction programs The release or organisms into an area where their species once lived Organisms are captured and bred, then returned to the wild Most successful when organisms are transported to new, sustainable habitats Ex. Brown pelican, gray wolf, panda breeding program, etc Captivity = an organism that is held by people Zoos & aquariums Animals kept in captivity may lose the necessary behaviors to survive in the wild