Principles of Ecology
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Chapter 2 Please complete the handout at your desk You have 10 minutes Ecology—the scientific study of organisms and their interactions with the environment Studies relationships of living and nonliving parts What kinds of questions might an ecologist ask? Ecologist would study: ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ What it eats Where it lives What other organisms it interacts with Patterns of dispersion What eats it Disease Impact on environment And more Biosphere—the portion of Earth that supports life The non-living components of an environment Examples: ◦ ◦ ◦ ◦ ◦ Rocks Air Temperature Light Moisture The living parts of an environment, including the organisms themselves Examples: ◦ ◦ ◦ ◦ ◦ People Plants Animals Fungi Bacteria Organism Population—a group of organisms of the same species within the same geographic location Biological Community—a group of interacting populations that occupy the same area at the same time Ecosystem—a biological community and all of its abiotic factors Biome—a group of ecosystems of the same climate and types of communities Biosphere A habitat is a place where an organism lives An ecological niche is the role and position of an organism within its environment Organisms or species cannot occupy the same exact ecological niche at the same time Why??? https://www.youtube.com/watch?v=xIVixvcR 4Jc Sym= Together Bio= Living Symbiosis is close association between two or more organisms There are a few key types of symbiotic relationships A type of symbiotic relationship where one organism clearly benefits because it is living at the expense of another (+/-) Both organisms in the relationship benefit (+/+) https://www.youtube.com/watch?v=dJRJCO5 9bf4 One organism benefits and the other is not affected (+/0) Example: Sea anemone and clownfish Autotrophs are organisms that use energy from the sun to manufacture their own nutrients Literally means “self feeder” Heterotrophs are organisms that must feed on other organisms and cannot make their own food Herbivore—eats plants Carnivore—meat eaters Omnivore—eats all Detritivore—eats dead organic material A food chain is a simple model that shows how energy flows through an ecosystem ◦ GrassCowHuman Food Webs are models representing interconnected food chains in which energy flows through a group of organisms Trophic Levels are steps in the food web or chain https://www.youtube.com/watch?v=Cd1M9x D482s Levels of energy passage Plants= producers Animals who cannot make their food are primary, secondary, tertiary, and quaternary consumers Then there are the detritivores Sun Key Chemical cycling Energy flow Heat Primary producers Primary consumers Detritus Secondary and tertiary consumers Microorganisms and other detritivores Tertiary consumers Secondary consumers 10 J 100 J Primary consumers 1,000 J Primary producers 10,000 J 1,000,000 J of sunlight Trophic level Biomass Pyramids Tertiary consumers Secondary consumers Primary consumers Primary producers Dry mass (g/m2) 1.5 11 37 809 (a) Most ecosystems (data from a Florida bog) Trophic level Primary consumers (zooplankton) Primary producers (phytoplankton) Dry mass (g/m2) 21 4 (b) Some aquatic ecosystems (data from the English Channel) Nutrient cycles in ecosystems involve biotic and abiotic components and are often called biogeochemical cycles Common cycles include ◦ ◦ ◦ ◦ ◦ ◦ Carbon Oxygen Sulfur Nitrogen Phosphorus Water Water is essential to all organisms Liquid water is the primary physical phase in which water is used The oceans contain 97% of the biosphere’s water; 2% is in glaciers and polar ice caps, and 1% is in lakes, rivers, and groundwater Water moves by the processes of evaporation, transpiration, condensation, precipitation, and movement through surface and groundwater Nitrogen is a component of amino acids, proteins, and nucleic acids The main reservoir of nitrogen is the atmosphere (N2), though this nitrogen must be converted to NH4+ or NO3− for uptake by plants, via nitrogen fixation by bacteria Nitrogen fixation is conversion of unusable forms of nitrogen into forms that plants and animals can use Denitrification is when fixed nitrogen is converted back into atmospheric nitrogen N2 in atmosphere Reactive N gases Industrial fixation Denitrification N fertilizers Fixation NO3− Dissolved organic N Aquatic cycling Runoff NH4 NO3− Terrestrial cycling Denitrification Decomposition and sedimentation Assimilation Decomposition Fixation in root nodules The nitrogen cycle N2 Ammonification NO3− Uptake of amino acids Nitrification NH4 Go to page 53 Respond to the “Constructed Response” questions #9, 10, 23, 34, 35 Take a look at each of the cycles starting on page 46 of your textbook ◦ ◦ ◦ ◦ Water Carbon/Oxygen Nitrogen Phosphorus Draw a simplified diagram of each of the four cycles and annotate it for your notes April 25, 2014 Take 8 minutes to look over your notes for the quiz HINT: It might be helpful to know how to make a cladogram If you talk during this time, you lose this time, so use it wisely What is YOUR community? A community is a group of interacting populations that occupy the same area at the same time It is not restricted to a single species or population, its all of the living things in the area How can communities vary? Could an organism survive in just any community? How does this tie into ecological niche? Limiting factors are biotic or abiotic factors in an ecosystem or community that restrict the numbers, reproduction, or distribution of organisms Can you think of any?? Sunlight Temperature Water Nutrients Fire Soil Chemistry Available Space Abiotic Factors Other living things Biotic Factors Every organism has an upper and lower limit for each limiting factor The ability of an organism to survive when it is subjected to biotic or abiotic factors is called tolerance A fire burns down a forest? A volcano erupts and flows over fertile land? Humans clear forests for lumber? Ecological succession is the change in an ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors Primary succession occurs in areas in which there is no layer of topsoil Secondary succession is the orderly and predictable change that occurs after a community or organisms have been removed but the soil has remained intact Climax communities occur when there is little change in the composition of a species Weather is the condition of the atmosphere at a specific place and time Latitude is the distance at any point of the Earth north or south from the equator Climate is the average weather conditions in an area, including temperature and precipitation Freezing temperatures Treeless Covered by layer of permafrost Contains some animals and shallow-rooted plants South of the tundra Evergreens Slightly warmer than tundra with longer summers No permafrost layer Used to be called taiga Cover southeast Canada, eastern US, most of Europe, and parts of Asia and Australia Composed of mainly deciduous (broadleafed) forest Has all four seasons Open woodlands and mixed shrub communities Less rainfall than temperate forest Occurs in Mediterranean, west coasts of North and South America, South Africa, and Australia Fertile soils Thick cover of grasses Found at middle latitudes No large trees Infrequent rainfall Exists on every continent except Europe Any area in which the annual rate of evaporation exceeds the annual rate of precipitation Sometimes resemble traditional desert, but sometimes do not Grasses and scattered trees Less rainfall than other tropical areas Mostly in Africa, Australia, and South America Very dry Almost all trees drop leaves in the dry season to conserve water Warm temperatures Large amounts of rainfall Central and South America Dense in biomass Much biodiversity Border tundra Cold all year Site of polar ice caps Members of the same species living and interbreeding in the same area Population density—the number of organisms per unit area Dispersion—the pattern of spacing of a population within an area Environmental and social factors influence the spacing of individuals in a population The most common pattern of dispersion is clumped, in which individuals aggregate in patches A clumped dispersion may be influenced by resource availability and behavior There is also uniform in which individuals are evenly distributed in an area Random distributions do not exhibit a pattern (a) Clumped (b) Uniform (c) Random (a) Clumped (b) Uniform (c) Random Density-Independent Factors are factors in the environment that do not depend on the members of the population per unit area ◦ Usually abiotic ◦ Examples? Density-Dependent Factors are factors in the environment that depend on the number of members in the population per unit area ◦ Examples? Change in population size can be defined by the equation Change in Immigrants population Births entering size population − Emigrants Deaths − leaving population If immigration and emigration are ignored, a population’s growth rate (per capita increase) equals birth rate minus death rate Exponential population growth is population increase under idealized conditions Under these conditions, the rate of increase is at its maximum and increases rapidly 2,000 Population size (N) dN 1.0N dt 1,500 dN 0.5N dt 1,000 500 0 0 5 10 Number of generations 15 Exponential growth cannot be sustained for long in any population A more realistic population model limits growth by incorporating carrying capacity Carrying capacity (K) is the maximum population size the environment can support In the logistic population growth model, the per capita rate of increase declines as carrying capacity is reached The logistic model starts with the exponential model and adds an expression that reduces rate of increase as population size approaches K Exponential growth Population size (N) 2,000 dN 1.0N dt 1,500 K 1,500 1,000 Population growth begins slowing here. 500 0 Logistic growth dN (1,500 N) 1.0N 1,500 dt 0 10 5 Number of generations 15 Fast reproductive strategies are known as Rstrategies Slow Reproductive strategies are called the Kstrategy R-selection (Quick and many Eg. Mice and rabbits) Large body size • Small body size Long life span • Short life span Take a long time to sexually mature • Sexually mature very quickly (weeks to months) Typically carry 1-2 young Protect and nurture their young High survivorship (type 1) of species over time. • Carry/hatch many young • Must care for themselves at an early age • Low Survivorship of young (many die) – type 3 https://www.youtube.com/watch?v=yTLX89_ Llxg Write the following words on a BRAND NEW sheet of paper: ◦ ◦ ◦ ◦ ◦ ◦ Flood Starvation Disease Earthquake Predation Space Circle the density dependent factors Underline the density independent factors You have 5 minutes Extinction is when the last member of a species dies Biodiversity is the variety of life in an area that is determined by the number of different species in that area Types of biodiversity ◦ Genetic ◦ Species ◦ Ecosystem Economic Value Health Maintaining Ecosystems Aesthetics Science Background extinction—gradual process of species becoming extinct Mass extinction—when a large percentage of all living things become extinct Lack of natural resources Overexploitation Habitat Loss Habitat Fragmentation When an overabundance of nutrients (usually N or P) in an ecosystem cause overgrowth of microorganisms and/or algae and upset the balance of an ecosystem The increasing concentration of toxic substances in organisms as trophic levels increase in a food chain or food web So what does this mean?? How does it happen?? Non-native species that are either intentionally or unintentionally transported to a new habitat What does this mean for ecological niches? Kudzu Zebra Mussel Restoration ecology seeks to initiate or speed up the recovery of degraded ecosystems Bioremediation is the use of organisms to detoxify ecosystems The organisms most often used are prokaryotes, fungi, or plants These organisms can take up, and sometimes metabolize, toxic molecules Biological augmentation uses organisms to add essential materials to a degraded ecosystem (a) In 1991, before restoration (b) In 2000, near the completion of restoration https://www.youtube.com/watch?v=iFeRFmq FChQ
