Chapter 13: Principles Of Ecology

Principles of EcologyEcologists study relationships in an environment.Words to know: ecology, community, ecosystem, biome, organism, populationEcology is the study of the interactions among living things, and between living things and their surroundings.Levels of Organization in an Environment 1. Organism – an individual species.Ex: an alligator 2. Population – a group of the same species that lives in one area.Ex: alligators in the swamp 3. Community – a group of different species that live together in an area.Ex: alligators, turtles, birds, fish and plants in the Florida Everglades 4. Ecosystem – includes all of the organisms as well as the climate, soil, water and rocks.Ex: Florida everglades with all of the plants, animals, soil, water and sun 5. Biome – a major regional or global community of organisms.Ex: Tropical rainforest, Tundra, DesertWhat level of organization describes a flock of pigeons in the park?Ecological Research Methods include Observation, Experimentation, and ModelingObservation Act of carefully watching something over time Can occur over short or long periods of time One type of population observation is surveys.o Direct Surveys - used for species that are easy to follow. (naked eye, binoculars)o Indirect Surveys - used for species that are difficult to track. (signs of presence) Radio Telemetry - used to track animal movement. Population sampling can also be used. Quadrat Sampling – used to monitor plant populations.o Scientists focus on the quadrat of plants in a random area and estimate from there.How might a scientist use observation to study a population of mountain goats? Explain your answer.Experimentation Experiments can be performed in the field or in the lab. A lab experiment allows for more control, but a field experiment gives a more accurate picture of howthe organisms interact in a natural setting.What is the difference between a lab experiment and a field experiment?Modeling Modeling is used when a question cannot be answered by observation or experimentation. Models are created with the use of real data, but are lab tools. Models can be used to: track populations, find vegetation, predict snow.How does modeling differ from experimentation?

Biotic and Abiotic FactorsWords to know: biotic, abiotic, biodiversity, keystone speciesAn ecosystem includes both biotic and abiotic factors. Biotic Factors - living things, such as plants, animals, fungi and bacteria Abiotic Factors - nonliving things, such as moisture, temperature, wind, sunlight, water and soilWhat is the difference between biotic and abiotic factors?Changing one factor in an ecosystem can affect many other factors. ALL species are affected by changes in biotic and abiotic factors in an ecosystem.Biodiversity Biodiversity - the assortment, or variety, of living things in an ecosystem The amount of biodiversity found in an area depends on many factors, including moisture andtemperature.Keystone Species The change in a single biotic or abiotic factor can cause changes that are barely noticeable or causethe extinction of a species. Keystone Species - a species that has an unusually large effect on its ecosystem.Ex: Beavers fell trees and create ponds, wetlands, and streams, which can lead to huge changes inan ecosystem.Explain why the Pacific Salmon could be considered a keystone species.Energy in EcosystemsWarm Up: 6H2O 6CO2 C6H12O6 6O2Why does life as we know it depend upon the formula written above?Words to know: producer, autotroph, consumer, heterotroph, chemosynthesis, photosynthesis.Producers provide energy for other organisms in an ecosystem. Producers - organisms that get their energy from nonliving resources Producers are also called autotrophs meaning “self-nourishment”. Consumers - organisms that get their energy by eating other living or once living resources, such asplants or animals Consumers are also called heterotrophs meaning “different-nourishment”. All ecosystems depend on producers because they provide the basis for the ecosystem’s energy. Most producers use sunlight to make food; therefore, almost all living things depend directly orindirectly on the sun as a main energy source.How would a long-term drought affect producers and consumers?Almost all producers obtain energy from sunlight. Photosynthesis - two-stage process used by most producers to make food Chemosynthesis - process in which an organism forms carbohydrates using chemicals rather thanlight, as an energy sourceHow do photosynthesis and chemosynthesis differ?

Food Chains and Food WebsWarm Up: What do you get from food? How does energy and matter come from the food you eat? Whatother way could you get energy for your body?Terms to know: food chain, herbivore, carnivore, omnivore, detritivore, decomposer, specialist, generalist,trophic level, food webFood Chain Model that shows a sequence that links species by their feeding relationships Rather than describe every potential relationship, this model chain only follows the connectionbetween one producer and a single chain of consumers within an ecosystem. Ex: Sun Grass Cottontail HawkTypes of Consumers Herbivores - organisms that eat ONLY plantsEx: deer, rabbits Carnivores - organisms that eat ONLY animalsEx: hawks, sharks Omnivores - organisms that eat BOTH plants and animalsEx: humans, bears Detritivores - organisms that eat detritus, or dead organic matterEx: vultures, hyena Decomposers - detritivores that break down organic matter into simpler compoundsEx: bacteria, fungus Specialist - consumer that primarily eats one specific organism or feeds on a very small number oforganismsEx: Florida snail kite depends primarily on apple snails Generalists - consumers that have a varying dietEx: Grey wolfTrophic Levels The levels of nourishment in a food chainEx: Producer Herbivore Carnivore has THREE Trophic Levels.The carnivore is the highest trophic level. Energy flows up the food chain from the lowest trophic level to the highest. Primary Consumers - herbivores Secondary Consumers - carnivores that eat Herbivores Tertiary Consumers - carnivores that eat secondary consumers Organisms can fall at different trophic levels based on where they fall in a food chain.What is the connection between food chains and trophic levels?Food Web Model that shows the complex network of feeding relationships and the flow of energy within andsometimes beyond an ecosystem. At each link in a food web, some energy is stored within an organism, and some energy is dissipatedinto the environment.How might the introduction of a new predator affect the flow of energy through a food web?

Cycling of MatterWarm Up: As humans, we are made of cells. Where does all that material come from? What would youinclude on a shopping list of elements that are critical to a human?Words to know: hydrologic cycle, biogeochemical cycle, nitrogen fixationWater Cycles through the Environment Matter changes form, but it does not disappear, it is used over and over again in cycles. The hydrologic cycle (water cycle) is the circular pathway of water on earth from the atmosphere, tothe surface, below, ground and back. Water Storage Evaporation Condensation Precipitation Runoff Water StorageRiverliquid to gasgas to liquidrain, snowgravity pulls downElements essential for life also cycle through ecosystems. A biogeochemical cycle is the movement of a particular chemical through the biological and geologicalparts of an ecosystem. Just as water changes states, so may other chemicals as they pass though cycles.The Oxygen Cycle Plants, animals, and most other organisms need oxygen for cellular respiration. Plants release oxygen as a waste product of photosynthesis. In turn, humans and other organisms take in this oxygen and release it as carbon dioxide throughcellular respiration.Explain how deforestation might affect the oxygen cycle.The Carbon Cycle Carbon is the building block of life; it is key to the structure of all organisms on our planet. Carbon exists in several forms: CO2 gas, bicarbonate dissolved in water, fossil fuels, limestone andorganic matter in soil. The simplest transfer of carbon occurs between plants and animals.o Plants use energy from the sun to convert carbon dioxide from the air into organic material thatbecomes a part of the plant’s structure. Carbon then moves through the biotic world as oneorganism eats another. Carbon is returned to the atmosphere as carbon dioxide by respirationor decomposition.The Nitrogen Cycle 78% of the Earth’s atmosphere is made of nitrogen gas. Certain types of bacteria convert gaseous nitrogen into ammonia (NH3) in a process called nitrogenfixation. Some nitrogen fixing bacteria live on nodules (bumps) on the roots of bean and pea plants. Nitrates released by soil are taken up by plants that convert the nitrates into amino acids and proteins. Animals then eat the plants and get the nitrogen. When decomposers break down animal excretions or dead animal and plant matter, nitrogen isreturned to the soil through ammonification. Denitrifying bacteria use nitrate as an oxygen source and release nitrogen gas into the atmosphere.The Phosphorus Cycle Most of the phosphorus cycle takes place at and below ground level. Phosphate is released by the weathering of rocks.

Plants and some fungus are able to take up phosphate.Phosphorus moves to consumers through the food chains and webs.When living things die and are decomposed, phosphorus is released back into the Earth.Choose one of the biogeochemical cycles, and list the key processes involved in the cycling of elements.Pyramid ModelsWarm Up: How is food energy measure? What do Calories measure?Words to know: biomass, energy pyramidEnergy Pyramid Shows the distribution of energy among trophic levels Ecosystems get their energy from sunlight. That energy then flows through food chains. Some energy gets lost in the process in the form of heat, so each level in a food chain contains muchless energy than the group before it.Loss of Available Energy Biomass is a measure of the total dry mass of organisms in a given area. When an organism consumes biomass a great deal of energy is given off as heat and waste. Scientists use the “Rule of 10”.o Each level in a food chain only gets 10% of the available energy from what it eats.Energy Pyramids An energy pyramid is a diagram that compares energy used by producers, primary consumers, andother trophic levels. Producers ALWAYS make up the bottom layer of the pyramid (they have the most energy). Sections become progressively smaller as you go up the pyramid since the amount of usable energysharply decreases. RULE: As you move up the energy pyramid, the amount of available energy goes down.Draw an energy pyramid for a desert food chain. Use arrows to illustrate the flow of energy.Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms. A biomass pyramid is a diagram that compares the biomass of different trophic levels within anecosystem. The pyramid shows the mass of producers needed to support primary consumers, the mass of primaryconsumers required to support secondary consumers, and so on. A pyramid of numbers shows the numbers of individual organisms at each trophic level in anecosystem.If a scientist wanted to compare the exact number of organisms at each trophic level within a desertecosystem, which pyramid model would he or she use? Explain.