Transcript Ecology
Concepts of Ecology CHAPTERS 3 AND 4 3–1 What Is Ecology? Objectives: Describe the study of Ecology Explain how biotic and abiotic factors influence an ecosystem Describe the methods used to study ecology What is ecology? Ecology is the scientific study of interactions among organisms and between organisms and their physical environment Interactions and Interdependence Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live. The interdependence of life on Earth contributes to an ever-changing, or dynamic, biosphere. Biosphere The biosphere contains the combined portions of the planet in which all of life exists, including: • land • water • air, or atmosphere The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean. Levels of Organization To understand relationships within the biosphere, ecologists may study these ecological levels of organization: Organism Population Community Ecosystem Biome Biosphere Organism: Individual member of a species- group of organisms that are physically similar and can interbreed with one another to produce fertile offspring Bison Copyright Pearson Prentice Hall Population Group of organisms of the same species living in the same area Bison herd Copyright Pearson Prentice Hall Community All populations that live together in a defined area Hawk, snake, bison, prairie dog, grass Copyright Pearson Prentice Hall Ecosystem All the populations and the physical surroundings Hawk, snake, bison, prairie dog, grass, stream, rocks, air Copyright Pearson Prentice Hall Ecosystem includes the biotic (living) and abiotic (nonliving) factors Biome Group of similar ecosystems that share similar climates and dominant communities of organisms (e.g tall grasses) Prairie biome Copyright Pearson Prentice Hall Biosphere The part of Earth that contains all ecosystems Copyright Pearson Prentice Hall Ecological Levels of Organization Methods Ecologists Use All of these approaches rely on the application of scientific methods to guide ecological inquiry Ecological Models Modeling- used to explain large-scale phenomena too large or too complex to study with observation or experiments alone Examples: Food webs Biogeochemical cycle diagrams Carbon cycle affects all levels of ecological organization up to the biosphere. A model helps make all aspects of the phenomenon observable 3-2 Energy, Producers, and Consumers Objectives: Define primary producers Describe how consumers obtain energy and nutrients Role of Primary Producers Energy is required for all life processes Energy flows from the sun or inorganic compounds to autotrophs (producers). Heterotrophs (consumers) eat producers to get energy. Without a constant input of energy, living systems cannot function. The primary source of energy on Earth is the sun Role of Primary Producers Autotrophs – “self feeder” Most use sunlight to create carbohydrates via photosynthesis Oxygen created as a byproduct Ex: Plants, some protists (algae) and some bacteria Some bacteria create organic compounds from inorganic chemicals in a process called chemosynthesis Live in remote places. Also can make carbohydrates and oxygen Energy Flow: Role of Producers Role of Primary Producers Autotrophs (plants, some bacteria) are called primary producers the first producers of energy-rich compounds that are later used by other organisms some of their self-made energy is stored and available to other organisms that eat them Mmm…this plant is delicious. Role of Consumers Heterotroph – “different feeder” Cannot harness energy directly from the physical environment. Must ingest food to obtain energy Ex: animals, fungi, some bacteria, some protists Energy Flow: Role of Consumers There are many different types of heterotrophs. Herbivores eat plants. Carnivores eat animals. Omnivores eat both plants and animals. Detritivores feed on plant and animal remains and other dead matter. Decomposers, like bacteria and fungi, break down organic matter. Scavengers consume carcasses of animals that have been killed by other predators Ch 3-3 Energy Flow in Ecosystems Objectives: Trace the flow of energy through living ecosystems Identify 3 types of ecological pyramids Food Chains Energy flows through an ecosystem in one direction from producers to consumers A food chain is a series of steps in which organisms transfer energy by eating and being eaten a single path of energy transfer in an ecosystem from the sun or inorganic compounds (not usually pictured) autotrophs (producers) various heterotrophs (consumers). Phytoplankton, floating algae, are primary producers in aquatic food chains Energy Flow: Food Webs A food web is the complex network of feeding relationships in an ecosystem links all the food chains in an ecosystem together Can provide information to determine the type of heterotroph Trophic levels Energy Flow: Trophic Levels Each step in a food chain or food web is called a trophic level. • Producers make up the first trophic level. • Consumers make up the second, third, or higher trophic levels. • Each consumer depends on the trophic level below it for energy. • A single organism may occupy more than one trophic level Energy Flow: Role of Decomposers Ecological Pyramids An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. Ecological Pyramids: Energy Pyramids Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level. Ecological Pyramids: Energy Pyramids Organisms use some of the energy for their own life processes Most is lost to the environment as heat Ch 3-4 Cycles of Matter Objectives: Describe how matter cycles among the living and nonliving parts of an ecosystem Describe how water cycles through the biosphere Explain why nutrients are important to living things Describe how the availability of nutrients affects the productivity of ecosystems 3-3 Cycling Matter Recycling in the Biosphere Matter is recycled within and between ecosystems. Matter moves through an ecosystem in biogeochemical cycles Biogeochemical Cycles 4 cycles of interest: water carbon nitrogen phosphorus Nutrients are all the chemical substances that an organism needs to sustain life. required to build tissues and carry out essential life functions Circulated throughout biosphere in biogeochemical cycles Water Cycle All living things need water Water Cycle Biotic parts of the ecosystem gain water by Drinking Absorption And lose it back to the environment through Transpiration (plants) Urination and exhalation of water vapor (animals) Carbon Cycle Nitrogen Cycle Nitrogen Cycle Nitrogen is needed for protein and nucleic acid synthesis 78% of Earth’s atmosphere is nitrogen gas (N2) Nitrogen containing products that can be used by plants Ammonia (NH4) Nitrate ions (NO3-) Heterotrophs can only get nitrogen by eating other organisms Bacteria and the Nitrogen Cycle Converting nitrogen gas into ammonia is called nitrogen fixation Only certain species of bacteria can do this Found living on plant roots or in soil Other nitrifying bacteria convert ammonia into nitrates A process called ammonification Plants use the converted products (NH4 and NO3-) to make plant proteins A process called assimilation Some bacteria convert nitrates into nitrogen gas (denitrification). Like in phosphorus and carbon cycles, bacteria act as decomposers returning nitrogen back to soil Root nodules on a legume Phosphorus Cycle Phosphorus Cycle Phosphorus is important for the formation of DNA and RNA molecules. Plants assimilate phosphorus that is in the soil Animals get phosphorus by eating other organisms Phosphorus is not very common and does not enter the atmosphere, instead it is found mostly on land in rock and soil. Carbon Cycle Required for photosynthesis Released during the process of cellular respiration Nutrients and Productivity o The primary productivity of an ecosystem is the rate at which organic matter (biomass) is created by producers. o One factor that controls the primary productivity of an ecosystem is the amount of available nutrients Nutrients and Productivity When a limiting nutrient, phosphorus, nitrogen, etc., is introduced it can cause bursts productivity Ex: algal blooms Compared to land, open oceans are nutrient poor Energy and Matter in Ecosystems: The Main Idea Energy flows in one direction Matter is transferred and recycled between the biotic and abiotic parts of ecosystems Niche An organism’s niche includes how it survives and reproduces in its environment. This includes: Place in food web Environmental conditions it needs to survive Type of food it eats How it obtains food Other species that use it as food When and how it reproduces What is the niche of a bullfrog? Niche Competitive Exclusion Principle - no two species can occupy the same niche in the same habitat at the same time Sharing a niche results in competition in nature often results in winner and loser – losing organism fails to survive Different species can occupy similar niches. Resource partitioning helps organisms with similar niches avoid competition Warbler Niches Cape May Warbler Feeds at the tips of branches near the top of the tree Bay-Breasted Warbler Feeds in the middle part of the tree Spruce tree Yellow-Rumped Warbler Feeds at the lower parts of the tree and bases of middle branches Community Interactions Competition- same or different species attempt to use an ecological resource in the same place at the same time Community Interactions Predation - one organism captures and feeds on another organism Predator – the one killing and eating Prey – the food Community Interactions-Symbiosis Symbiosis- an interaction between two species living close together Three types: Parasitism – one is harmed (host), one benefits (parasite) Mutualism – both benefit Commensalism – one is neutral, one benefits Mutualism Parasitism Commensalism