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This unit explores the roles of producers, consumers, and decomposers in an ecosystem, as well as the concept of trophic levels. It also examines the structure and diversity of food webs, the movement of energy through an ecosystem, and the cycles of chemicals such as water, carbon, and nitrogen. Additionally, it discusses the concept of niche, adaptation, and population dynamics within an ecosystem.
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Environmental Science Unit 2 – Ecological Interactions
4.1Roles of Living Things Objectives • Identify the roles of producers, consumers and decomposers • Describe the concept of tropic level.
Chapter 4 Role of Living Things Producers: Photosynthesizing organisms Consumers: any organism that can’t make its own food • Herbivore – eats only plants • Carnivore – eats only herbivores or other carnivores • Omnivores - eats either producers or consumers • Scavengers – feed on bodies of dead organisms Levels of consumers : Primary – eats plants Secondary – eats animals that eat plants Tertiary – eat animals that eat animals that eat plants Decomposers: An organism that primarily feeds on dead organisms or the waste from living organismsmainly bacteria and fungi
Trophic Levels A layer in the structure of the feeding level of a systems Heterotrophs: eat other organisms Autotrophs: make their own food
4.2Ecosystem Structure Objectives • Describe food chains and food webs. • Examine the effects of ecosystem structure on population size and pollution.
Food Chain: a series of organisms that transfer food between the tropic levels of an ecosystems Food Web: a network of food chains = not simple ! Chapter 4 Ecosystem Structure
Example: • Whales were over hunted • Their primary food source (krill) became over abundant. • More krill meant more penguins & seals Chapter 4 Interconnections
Which food web represents a more mature ecosystem? Which food web is more stable? Chapter 4 Diversity and Stability
More There are increasing concentrations of pollutants in organisms at higher trophic levels of food webs Chapter 4 Biological magnification
4.3Energy in theEcosystem Objectives • Investigate the movement of energy through an ecosystem. • Define ecological pyramid, and explain its relationship to energy in an ecosystem.
Energy and Food Producers use little of the sunlight that reaches them, the energy captured is used to make cells in both producers and consumers. The total amount of organic matter present in a trophic level is calledbiomass. 10% Law
10% Law 10% Law is the main reason most food chains have five or less links. In this example – the biomass of the owl population simply could not support another level.
Ecological Pyramid Ecological Pyramidis a diagram that shows the relative amounts of energy in different trophic levels in an ecosystem.
Biomass Pyramid Ecological Pyramids can show the biomass and numbers (of organisms) as well as energy.
4.4Chemical Cycles Objectives • Describe the chemical composition of the human body. • Explain the water cycle, the carbon cycle and the nitrogen cycle.
The Human Body 4 elements make up 96% of your body. • Oxygen 65% • Carbon 18.5% • Hydrogen 9.5% • Nitrogen 3.5% the rest ~4%
Chapter 4 Quiz
Chapter 5.1 Habitats & Niches • Describe the concept of niche. • Examine how interactions between a species and its environment define the species’ niche.
Chapter 5.1 Niches Niche refers to a populations role in its ecosystem • food • habitat • reproduction method
includes both Biotic • Competitors • Predators • Decomposers • Population Density Abiotic Chapter 5.1 Niche influence • Soil pH • Soil Humidity • Soil Temperature • Air Temperature • Wind Speed • Sunlight Intensity • Soil Nutrients
Crickets Ants Overlapping niches – species can coexist Hawks Owls Both species share the same niche – one will disappear Chapter 5.1 Competitive Exclusion The extinction of a population due to direct competition with another species for resources is
Predator is an organism that actively hunts other organisms. Keystone predator is an animal that causes a large increase in the diversity of its habitat. Chapter 5.1 Niche Diversity
Explain how a species adapts to its niche. • Describe convergent evolution and coevolution, and relate each to the concept of niche. Chapter 5.2 Evolution and Adaptation
Evolution, changes in a population of organisms over time. Chapter 5.2 Evolution
Populations evolve by adapting to niches in the environment, dividing available resources (avoiding competition) Chapter 5.2 Evolving to the Niche Specialized species vs. Generalized species
Convergent Evolution, is development of similar adaptations in two separate species with similar niches Chapter 5.2 Convergent Evolution
Coevolution, species which interact closely and adapt to one-and-other (even predator & prey) - evolve together Chapter 5.2 Coevolution
Unchecked populations growth leads to exponential growth Chapter 5.3 Populations
A population’s limit as defined by its ecosystem is its carrying capacity Chapter 5.3 Populations
Density-independent limiting factors Human Disturbance Climate Natural Disasters Population Size Predation Water Availability Chapter 5.3 Limiting Factors Living Space Parisitism Food Competition Disease Density-dependent limiting factors
Chapter 5 Quiz
Environmental Science Chapter 6 - Ecosystem Balance
Chapter 6.1 Relationships in the Ecosystems Objectives • Explainthe relationship size between populations sizes of predator and prey • Define symbiosis and state the effects of symbiotic relationships on populations
Chapter 6.1 - Predator and Prey Predator – a consumer that actively hunts and prey – organisms upon which predators feeds
Chapter 6.1 - Predator and Prey Population Cycles The populations of predator and prey are closely linked. Snowshoe hare = Lynx = N1 N2
Eyelash Mite Chapter 6.1 - Parasitism Parasitism – one organism feeds on the tissues or body fluids of another Keys to Parasite survival • Eat enough to live and reproduce • But not so much that you kill your host
Chapter 6.1 - Symbiosis Symbiosis – a relationship where two species live together closely. Parasitism is an example of symbiosis. Commensalism • One species benefits, and neither helps nor harms the other Mutualism • Both species benefits
Objectives • Describe the process of primary and secondary succession • Illustrate the evolution of many species from a single ancestor during the process of island succession Chapter 6.2 Ecological Succession
Primary Succession • Sequence of communities forming in an originally lifeless habitat Chapter 6.2 Ecosystem Successions
Lichens • A fungus and an algae living in a mutualistic relationship • Important because able to break down bare rock using stored acid • Pioneer community Chapter 6.2 Lichens
Climax community • Community that does not undergo further succession Chapter 6.2 Climax Community
Secondary community • Succession that occurs when a community has been cleared by a disturbance, but does not disturb the soil Chapter 6.2 Secondary Community
Chapter 6.2 – Other Successions Aquatic Such as what might happen in an oxbow lake Island succesion, birds often populate unfilled niches. Darwin’s Finches
Objectives • Examine the concepts of ecosystem balance and explain how humans affect that balance. • Explain that disturbance is a natural part of all ecosystems, but that disturbances trigger changes in ecosystems. Chapter 6.3 Balance in the Ecosystem
All natural ecosystems are stable, they maintain a state of balance called equilibrium. Food-web is heart of the system Chapter 6.3 Balance in the Ecosystem
Humans build houses such that salamanders vernal pools are eliminated, what might happen? Chapter 6.3 Human affect on Balance VOID
