Chapter 18: Ecology

What is Ecology?? The study of interactions that take place between organisms and their environment. It explains how living organisms affect each other and the world they live in.

Habitat & Niche Habitat is the place a plant or animal lives Niche is an organism’s total way of life—habitat and its role in environment

Niches A niche is determined by a limiting factor. Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

Limiting Factors Examples of limiting factors - Amount of water Amount of food Temperature Amount of space Availability of mates

The Nonliving Environment Abiotic factors- the nonliving parts of an organism’s environment. Examples include air currents, temperature, moisture, light, and soil. Abiotic factors affect an organism’s life.

The Living Environment Biotic factors- all the living organisms that inhabit an environment. All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection.

Abiotic or Biotic? Biotic

Abiotic or Biotic? Abiotic

Abiotic or Biotic? Abiotic

Abiotic or Biotic? Biotic

Levels of Organization in Ecology

What are the Levels? Organism Population Community Ecosystem Biosphere

1st Level of Organization Organism: An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops

2nd Level of Organization Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time.

3rd Level of Organization Community: All the populations of different species that live in the same place at the same time.

4th Level of Organization Ecosystem: Populations of plants and animals that interact with each other in a given area with the abiotic components of that area.

5th Level of Organization Biosphere: The portion of Earth that supports life.

The Biosphere Life is found in air, on land, and in fresh and salt water. The BIOSPHERE is the portion of Earth that supports living things.

Energy Transfer Producers: autotrophs that capture energy and use it to make organic molecules *Photosynthesis *Chemosynthesis Biomass: organic material that has been produced in an ecosystem

Energy Transfer Consumers: heterotrophs that obtain energy by consuming organic molecules made by other organisms *Herbivores: eat producers *Carnivores: eat other consumers *Omnivores: eat both producers and consumers *Detritivores: feed on the “garbage” of an ecosystem via oral ingestion -Decomposer: a detritivore that breaks down organic material by the release of enzymes = decomposition

Energy Flow Trophic Level: indicates organism’s position in a sequence of energy transfers *1st trophic level = producers *2nd trophic level = herbivores *3rd+trophic level = consumers -Higher trophic levels contain less energy, so they support fewer individuals

Energy Transfer Through Trophic Levels

Energy Pyramids Show : Amount of available energy decreases for higher consumers It takes a large number of producers to support a small number of primary consumers It takes a large number of primary consumers to support a small number of secondary consumers

Food Chains and Food Webs Food Chain: single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer Food Web: Interrelated food chains in an ecosystem On average, only 10% of the total energy consumed in one trophic level is incorporated into organisms in the next

Food Web

Ecosystem Recycling As energy and matter flow through an ecosystem, matter must be recycled and reused. Substances such as water, carbon, nitrogen, and phosphorus each pass between the living and nonliving worlds through biogeochemical cycles

The Water Cycle Key processes in the water cycle are evaporation, transpiration, and precipitation. Evaporation: Movement of water from soil & bodies of water (lakes, ponds, etc.) to the air (turning into gas) Transpiration: Loss of water through a plant’s stomata; liquid water turns to gas Precipitation: Water released from the atmosphere (rain, snow, sleet, hail)

The Water Cycle Transpiration and evaporation remove water from Earth’s surface The liquid water is turned into gas as it enters the atmosphere Precipitation adds liquid water to Earth’s surface

The Carbon Cycle Photosynthesis and cellular respiration are the two main steps in the carbon cycle. Decreased rates of photosynthesis = excess CO2 in atmosphere (inversely-related) Increased respiration = excess CO2 in atmosphere Burning of fossil fuels = excess CO2 in atmosphere Decomposition/decay = adds CO2 to soil

Carbon Cycle

Nitrogen Cycle Nitrogen-fixing bacteria are important in the nitrogen cycle because they change nitrogen gas into a usable form of nitrogen for plants. N2 (gas) converted by bacteria into NO3 (nitrates) to be used by plants

Nitrogen Cycle

Phosphorus Cycle In the phosphorus cycle, phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean. MOST IMPORTANT POINT: PHOSPHORUS IS NOT IN THE ATMOSPHERE

Phosphorus Cycle