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Ecology Chapter 3.1 to 3.3 1 What is Ecology? • Ecology – the study of interactions among organisms and between organisms and their environment • Biosphere – the largest of the areas of the earth containing the portion of the planet that life exists, including land, water and air (atmosphere) 2 Levels of Organization Ranges in complexity from single individual to entire biosphere. 3 Levels of Organization • Individual – one organism • Population – group of individuals that belong to the same species and live in the same area – Species - a group of individuals so similar to one another that they can breed and produce fertile offspring. • Community –different populations that live together is a defined area • Ecosystem – all the organisms that live in a similar area along with the nonliving material • Biome – group of ecosystems (similar climate) • Biosphere – entire earth 4 Ecological Methods • Scientists use 3 basic methods to conduct ecological research. 1. Observing – qualitative and quantitative observations 2. Experimenting – used to test hypotheses, can set up artificial environments and manipulate conditions 3. Modeling – models are made to study events that have occurred over large time periods, or are large in scale 5 Interactions Among Organisms- Energy Flow • Sunlight is the main energy source for life on Earth • Producers – autotrophs (make their own energy using the sun) – Photosynthesis – using light to produce energy / food – Chemosynthesis – using inorganic molecules to produce energy / food 6 Energy Flow Photosynthesis Chemosynthesis 7 Energy Flow • Consumers – heterotrophs (cannot make their own energy) – Herbivores – consume plants – Carnivores - consume meat – Omnivores – consume both – Detritivores –feed on dead or decaying matter • earthworms, mites, crabs, snails – Decomposers – break down organic matter • bacteria & fungus 8 Energy Transfer / Feeding Relationships • Energy flows in one direction • Food Chain- series of steps where energy is transferred by eating and being eaten • Trophic Levels – each step in a food chain • Food Web –links all food chains in ecosystem together 9 Food Chain vs. Food Web 10 Ecological Pyramids • Diagram that shows relative amounts of energy or matter contained within each trophic level in a food chain or food web for an ecosystem 1. Energy Pyramid – energy available at each trophic level - 10% rule 2. Biomass Pyramid – amount of living tissue/potential food available in each level 3. Pyramid of Numbers - number of individual organisms 11 Examples of Pyramids 12 Recycling in the Biosphere • Water Cycle – Evaporation, precipitation, condensation, transpiration, run-off, ground water – Video – Song 13 Nutrient Cycle • Carbon Cycle – carbon fixation, CO2 • Photosynthesis, respiration • Fossil fuels • Human Activities – Mining, cutting forests, burning fossil fuels Video Video 14 Biogeochemical Cycles • Nitrogen cycle – nitrogen fixation (bacteria), denitrification • Video • Video 15 Biogeochemical Cycles • Phosphorus Cycle – Does not enter atmosphere. – In land, rocks, soil and ocean sediment as inorganic phosphate. – Will dissolve in water. Video 16 Nutrient Limitation • Primary Productivity – rate of production of organic matter by producers – Amount of available nutrients. • Limiting Nutrients – nutrient that limits productivity when scarce. • Aquatic ecosystems – large input of limiting nutrient can cause an increase of algae or producers = algal bloom 17 Chapter 4.2 What shapes an ecosystem? 18 Biotic Factors • Biological influences on organisms within an ecosystem – Include all living organisms. – Cast of characters that an organism might interact with – Bullfrog: • Plants and algae as a tadpole • Herons that eat adult bullfrogs • Other species that compete with frog for space and food. 19 Abiotic Factors • Physical or non-living factors that shape an ecosystem – Climate: • Temperature, precipitation, humidity. – Wind, nutrients availability, soil type, sunlight • Biotic and Abiotic factors together determine the survival and growth of an organism and productivity of an ecosystem 20 Niche • An organisms habitat is its address, its niche is its occupation. • Full range of physical and biological conditions in which it lives and the way the organism uses these conditions. – Type of food it eats, how it obtains food, what other species use the organism as food. 21 Community Interactions • Competition- when organisms of same or different species attempt to use an ecological resource in the same place and at the same time. • Resource- necessity of life • Competitive Exclusion PrincipalNo two species can occupy the same niche in the same habitat at the same time. – Losing organism will fail to survive. 22 Community Interactions • Predation- One organism captures and feeds on another organism. • Symbiosis- “living together” – Mutualism- both benefit • Flowers and insects – Commensalism- one benefits, other is neither helped nor harmed. • Barnacles on marine animals – Parasitism- one organism lives on or inside another and harms it. • Tapeworms, fleas, ticks, lice 23 Label each 24 Ecological Succession • Predictable changes that occur in a community over time. • Ecosystems are constantly changing in response to natural and human disturbances. • As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further change. 25 Ecological Succession • Primary Succession -occurs on surfaces where no soil exists – Volcanic eruptions, bare rock – Pioneer species- first species to populate • Often lichens (fungus and algae) – When they die they add organic material to become soil. • Secondary succession – a disturbance changes an existing community without removing soil. – Land clearing and farming – Wildfires 26 Chapter 5.1 to 5.2: Populations 27 Three important characteristics of a population • 1. Geographic Distribution/Range – Area inhabited by a population – Varies in size- Microscopic to miles • 2. Population Density – Number of individuals per unit area. – Can again vary greatly • 3. Population Growth Rate – A. Number of Births – B. Number of Deaths – C. Number of individuals who have entered/leave population = immigration and emigration 28 Types of Population Growth • Exponential Growth– Under ideal conditions with unlimited resources. – Will start out slow and then approaches an infinitely large size - J curve – Reproduce at a constant rate - Not in natural populations! • Logistic Growth – Populations growth will slow or stop after a period of exponential growth – As resources become less available, the growth of a population slows or stops - S curve – Reached carrying capacity- number of individuals that a given environment can support 29 30 Limits to Growth • Limiting factors cause population growth to decrease. – Density Dependent- only become limiting when a population reaches a certain level (TOO LARGE) • • • • Competition Predation Parasitism Disease – Density Independent- affects populations in same way regardless of size • Unusual weather, natural disasters, seasonal cycles, human activities 31 Chapter 6.2 to 6.4: Humans in the Biosphere 32 Classifying Resources • Renewable resources- can regenerate or can be replenished by biochemical cycles – Can be living or nonliving • Nonrenewable resource- cannot be replenished by natural process. – Fossil fuels: coal, oil, natural gas. • Classification depends on context – EX: Trees • Single vs. entire population • Sustainable development – Using natural resources without depleting them. 33 Different types of Resources • Land Resources – Soil erosion- wearing away of soil by wind and water – Desertification-turning once productive areas into deserts. • Forest Resources – Deforestation- loss of forests • Fishery Resources – Overfishing – Aquaculture- raising aquatic animals for human consumption • Air Resources – Smog, pollutant • Freshwater Resources – Pollution 34 Biodiversity: Greatest Natural Resource • Sum total of all the genetically based variety of all organisms in the biosphere – Ecosystem Diversity • Habitats, communities, ecological processed – Species Diversity • Number of different species in the biosphere – Genetic Diversity • Sum total of all the genetic information carried by all organisms living on earth today. 35 Threats to Biodiversity • Extinction- species disappears • Endangered species- population size declining • 1. Habitat Alteration – Habitat fragmentation- development splits ecosystems into pieces • 2. Demand for wildlife products • 3. Pollution – Biological Magnification- concentration of harmful substances increases at higher trophic levels • 4. Introduced species – Invasive species- reproduce rapidly because of lack of predators • Conservation efforts are in place to manage natural resources. 36 Biological Magnification 37 Charting the course for the future • Researchers are gathering data to study the effects of human activities on the biosphere. • Ozone depletion. – Ozone layer- 20-50 kilometers above earth surface. Absorbs UV light before it reaches earths surface. • Global climate change – Global warming- increase in average temperature of biosphere. 38