Chapters 3-6: Ecology

Ecology• study of interactions that take place

between organisms and their environment

Biosphere

• Part of the Earth that holds all living things• Air, land, and sea• Living things affected by nonliving and

living things

• Abiotic factors– Nonliving parts of an environment– Temperature, moisture, light, soil…etc

• Biotic factors– All living organisms that inhabit an environment– Plants, other animals– Depend on others directly or indirectly

• Food, shelter, reproduction, protection

Levels of Organization

• Organisms make up population

– Group of organisms of the same species

– Interbreed and live in the same area

– Can compete for food, water, mates

• # of populations make up community

–Made up of interacting populations

–Change in a population can affect entire community

• Populations + abiotic factors make up ecosystem–Terrestrial (land): forests, meadows–Aquatic (water): oceans, lakes, ponds,

rivers

• Habitat: place where an organism lives

• Can change or disappear because of natural and human causes

• Niche: all the ways and adaptations a species uses in its environment

• How it meets its needs for food, shelter, survival, reproduction

– Biotic + abiotic parts of the environment

Predation• consumers

• Eat plants and animals

• Eat prey (animals that predators eat)

• Fight for survival

Symbiosis• Relationship where there is a

close and permanent association between different organisms

• Means “living together”

• 3 kinds

Mutualism

• Both species benefit (+,+)

Commensalism

• one benefits and the other does not benefit or is harmed (+,o)

Parasitism

• one benefits and the other is harmed (+,-)

How Organisms Get Energy

• Sun is the ultimate form of energy and source for energy

• Producers: autotrophs

–Uses light to make own food (photosynthesis) and energy

• Ex: grass, trees, green algae

Consumers

• Heterotrophs

• Eat other organisms to get energy

• CANNOT make its own food

Herbivores• Only eat plants

Carnivores• Only eat animals

Omnivores• Eat both plants and animals

Scavengers• Eat on dead organisms

Decomposers• break down and

release nutrients from dead organisms

Flow of Matter and Energy

• You consume matter when you eat food

–Carbon, nitrogen, other elements

• Energy flows through levels of the entire ecosystem

–Only some energy is transferred from 1 energy level to the next

Food Chains• show how matter and

energy move through an ecosystem– Nutrients and energy

move from autotrophs to heterotrophs and then decomposers

– Ex: grass rabbit wolf

– Arrows indicate the direction energy is transferred from one organism to the next

Ecological Pyramid• shows how energy

flows through an ecosystem

– Energy that is transferred from one trophic level to the next is only 10%

Trophic Level• A feeding step in passing of energy

and materials

Heterotroph

Heterotroph

Herbivore

Autotroph

Food Webs• all the possible relationships at each

trophic level of a community

Chapter 3-6 Review #1:1. Which of the following types of heterotrophs eat

other animals? a. omnivores & carnivores c. carnivores only

b. herbivores & omnivores d. carnivores & herbivores

2. Which of the following types of heterotrophs would bacteria and fungi be classified as?a. detritivores b. herbivores c. carnivores d. decomposers

3. What is the one-way flow of energy in an ecosystem called?

a. food chain b. energy pyramid c. food web d. biomass pyramid

4. What is each step in a food chain or food web called?

Limiting Factors• Affect an organism’s ability to survive in its

environment

• Ex: water, food, predators, temperature

• Density-dependent: disease, competition, parasites, food

– Depend on the density of a population

• Density-independent: affects all populations regardless of their density

– Temperature, storms, floods, drought, and habitat disruption

Succession

• Natural changes and species replacement that takes place in communities in an ecosystem– Occurs in stages

• Primary succession– Colonizing bare land where there are no

organisms– Pioneer species: 1st species in an area

Climax Community• Stable, mature community that

has little or no changes in species

Secondary Succession

• Changes that occur when existing community is disrupted by natural disasters or human actions

Biomes• Large group of

ecosystems that share the same type of climax community

• Terrestrial or aquatic– Aquatic: marine,

estuaries, freshwater, swamps

– Terrestrial: tundra, taiga, desert, grassland, rain forest, temperate forest

Population Growth• Organisms can

grow exponentially

• Exponential growth: as a population gets larger, it also grows faster

– J-shaped curve (diagram):

• Growth will be limited at some point by limiting factors

• Food availability, disease (ex: AIDS, influenza, TB, Dutch Elm disease, Pfiesteria), predators, lack of space

• Results in an S-shaped curve• Diagram:

• Carrying capacity: the number of organisms of a species that an environment can hold

Define these terms:

• Birth rate

• Death rate

• Emigration

• Immigration

• Zero population growth

Biological Diversity• Biodiversity: the variety of species in a specific area

• Loss of biodiversity is increasing

• Extinction: disappearance of a species when the last organism dies

• Ex:

• Endangered species: # of species become low that can lead to extinction

• Ex:

• Threatened species: population likely to become endangered

• Ex:

Cycles in Nature• Matter is constantly being

recycled

Water Cycle• Water evaporates from lakes and oceans to

become water vapor in the air

• Water vapor in the air condenses to form clouds

• More water condensation leads to precipitation, falling as rain, ice, or snow back to the ground

• Cycle repeats constantly

• Problems with the cycle:

Carbon Cycle• Starts with autotrophs

–Makes carbon molecules from CO2 during photosynthesis

• Heterotrophs feed on autotrophs, getting those carbon molecules

• Release CO2 back into the atmosphere

Problems with Cycle

• Global Warming:

–Greenhouse effect

–Gases that lead to global warming

Nitrogen Cycle• Lightning and some bacteria convert nitrogen in the air

into a usable form• Plants use nitrogen to make proteins• Herbivores eat plants

– Convert nitrogen-containing plant proteins into animal proteins

• Humans eat plants– Convert animal proteins to human proteins

• Excess nitrogen in animals released in urine– Returned to water or soil

• Nitrogen molecules return to the soil when animals die– Re-used by plants– Bacteria put nitrogen back into the air

Phosphorous Cycle• All organisms need phosphorus for

growth and development

• Plants get phosphorus from the soil

• Animals get phosphorus by eating plants

–Decompose when they die, returning phosphorus to the soil

Problems:

• Eutrophication

Impact of Human Activities on the Environment

• Population growth

• Pollution

• Global warming

• Burning fossil fuels

• Habitat destruction

• Introducing nonnative species

Chapter 3-6 Review #2:1. A lone elephant joining another herd of

elephants is an example of a. emigration c. immigration

b. parasitism d. exponential growth

2. What term is used to describe a species whose population is rapidly shrinking and might disappear completely?a. endangered c. extinct

b. threatened d. invasive