I. Introduction to Ecology Unit 1

Ecology: The study of how organisms interact with each other and their environment

Themes of this unit Organisms are interdependent with each other. Living things capture energy, transform it for use, and transfer it to other organisms. Ecosystems are relatively stable over time but show variation. This is called dynamic equilibrium.

Biotic vs. Abiotic factors Biotic: living factors: predators, prey, mates Abiotic: non- living factors: water, light, soil

1.Organism 2.Population: all organisms of one species in an area 3.Community: all of the living organisms (populations) in an area 4.Ecosystem: all biotic and abiotic factors in an area Levels of Organization

5.Biome: major region characterized by specific plants, animals, and climate 6.Biosphere: all areas of the Earth that can sustain life

II. Energy Flow Unit 1

Trophic Levels Producer: autotrophs, make own food by capturing sun’s energy Consumer: consumes and gets energy from other organisms in the food web Decomposer: breaks down dead organic matter and returns materials to the soil

Types of Consumers In order in a food chain: – Primary consumer – Secondary consumer – Tertiary consumer Names: – Herbivore: eats plants – Omnivore: eats plants and animals – Carnivore: eats animals – Detrivore (scavenger): eats dead organisms

Food Chains Flow of energy from one organism to another. Arrow indicates direction of energy flow.

Food Webs Interconnected food chains in a community. More realistic than one food chain.

Ecological Pyramids Categorizes organisms by trophic levels. Shows amount of organisms and energy available at each level.

Ecological Pyramids Only 10% of energy is transferred from one level to the next. The rest is lost as heat and work when organisms USE energy to live. Higher trophic levels = LESS energy available.

III. Nutrient Cycles Unit 1

The Water Cycle precipitation condensation transpiration evaporation water storage runoff

The Water Cycle 1.Evaporation: liquid water changed to water vapor (gas) 2.Condensation: water vapor condenses to a liquid in clouds 3.Precipitation: liquid water falls from sky to earth 4.Transpiration: evaporation of water from the leaves of plants

The Carbon Cycle fossil fuels CO 2 in water decomposition respiration CO 2 in air photosynthesis combustion

The Carbon Cycle Carbon fixation: CO 2 captured from atmosphere by plants in photosynthesis Respiration: releases CO 2 into the atmosphere (performed by ALL organisms) Burning of fossil fuels: releases stored carbon for millions of years (oil, gas, coal) into the atmosphere

The Nitrogen Cycle Atmospheric Nitrogen animals Nitrogen that living things can use decomposers plants nitrogen- fixing bacteria

The Nitrogen Cycle 1.Nitrogen Fixation: bacteria capture nitrogen from atmosphere for plants to use. 2.Other organisms get nitrogen by consuming plants. 3.Denitrification: bacteria release nitrogen back into the atmosphere

IV. Competition & Cooperation Unit 2

Ecosystem Interactions Habitat vs. Niche: Habitat: where an organism lives Niche: an organism’s role in the environment Organisms interact in their environment through competition, symbiotic interactions and predation.

Competition We often think of animals as competing with each other for resources, but look at one instance of direct plant competition: 503F99BB F99BB5 How else are plants competing (in less obvious ways)?

Competitive Exclusion Principle: Two species cannot exist in the exact same niche. One will always have some slight advantage and outcompete the other. Is the competitive exclusion principle a theory or a law?

Generalist vs. Specialist Generalists have very broad niches: they can tolerate a broad range of conditions and use a variety of resources. – Examples? Specialists have very narrow niches, living in only a specific set of conditions eating specific resources. – Examples?

Symbioses: close, often long-term interactions between two different species Mutualism: Both organisms benefit in the relationship. – Example: oxpecker and rhino. Bird eats ticks off of a rhino for food and the rhino’s pests are taken away. – Any other examples??

Symbioses Parasitism: one organism benefits and the other is harmed. – Ex. Dog and heartworm. Heartworm is supplied food and the dog is hurt.

Symbioses Commensalism: One organism benefits and the other is not affected. – EX. Remora fish has a suction disk which attaches it to a shark. The fish is protected and can grab bits of food that the shark drops. The shark is not affected.

V. Populations Unit 2

Human Population

Population Growth Limiting factors: environmental factors that limit the size of a population – Ex) space, water, predators, food

Limiting Factors Density-Dependent Factors: limiting factors that depend on how many organisms there are in an area – Food, water, space, predators, disease Density-Independent Factors: limiting factors that don’t depend on how many organisms there are in an area – Drought, flooding, extreme heat/cold, etc.

Logistic Growth Curve A.Lag phase B.Exponential growth C.Steady state K = Carrying capacity: the number of organisms that can be supported long term by an ecosystem b c

Population Growth is affected by… Natality – birth of organisms Immigration – new individuals move INTO the population Mortality – death Emigration – individuals move OUT OF the population

Reproductive Strategies r-strategists – Have as many offspring as possible, low parental investment in survival – Organisms often small, prey, changing conditions k-strategists – Have few offspring, high parental investment in survival – Organisms often larger, predator/not-prey, stable conditions

Is this rate of growth sustainable? If we were to get close to our carrying capacity (which would be BAD) based on our current lifestyles, how could we change our habits to increase the carrying capacity? (HINT: think about our discussion of trophic efficiency)

VI. Ecological Succession Unit 2

Ecological Succession Change in an environment over time. Species gradually replace one another. Primary succession: beginning of a new community where one has not existed before. Starts with bare rock (no soil)

Ecological Succession Secondary succession: new community developing after disturbance to an existing community. Soil still remains.

Ecological Succession Pioneer species: First organisms to occupy an area Climax community: stable end community that characterizes a region The climax community in Virginia is a temperate deciduous forest (oaks, maples, hickories, pines)

Ecological Balance Dynamic Equilibrium means that ecosystems maintain balance. Ecosystems are relatively stable over time. However, this balance may be disturbed by the introduction of new species, the extinction of species, or man-made causes.