Chapter 2 – Ecology

I. Ecology - the study of interactions that take place between organisms and their environment

This wildfire affects plants, animals, and humans living in this area

A. The Environment is made up of Biotic and Abiotic Factors

1. Biotic Factors – living parts of the environment

Bacteria (our gut) Fungi (mushroom) Protists (algae)

Plants (cotton) Animals (bobcat)

2. Abiotic Factors – nonliving parts of the environment

air, temperature, light, minerals, water, soil

Food Production in Salt Bush

Food

pro

duct

ion

(mg

of g

luco

se/h

r) 15

10

5

10 20 30 40 50Temperature (°C)

This graph shows how the plant’s food production is affected by temperature

II. Ecologists have organized the living world into levels—the organism by itself, populations, communities, ecosystems, biomes, & the biosphere

A. Organism – an individual living thing

1 antelope

B. Population – a group of organisms (all of the same species) which interbreed and live in the same area at the same time

1. They compete with each other for food, water, mates, or resources

a group of antelope

C. Community - made up of several different interacting populations in a certain area at a certain time

antelope and zebras

1. Different popns. may or may not compete for the same resources

2. Predation – some organisms pursue others for food (prey)

D. Ecosystem – biotic factors that interact with each other in a given area and with the abiotic factors of that area

antelope, kudu, water, air, trees

E. Biome – large group of ecosystems that share the same climate & have similar types of communities

F. Biosphere - the portion of Earth that supports living things; made of

all the biomes

1. It extends from the atmosphere to the bottom of the oceans

No life in the mantle or core, inside the earth

III. Types of Ecosystems

A. Terrestrial – located on land

forest old farm field

volcano rotting log

B. Aquatic – freshwater and saltwater forms

1. Freshwater Ecosystems:

pond streamlake

2. Saltwater/Marine Ecosystems:

oceans, estuaries,

aquariums

C. Other Ecosystems

digestive system skin

mold in walls refrigerator

IV. Organisms in Ecosystems

A. Habitat - the place where an organism lives out its life (its address)

B. Niche - the role or position a species has in its environment (its profession); includes how it gets its energy (autotroph or heterotroph)Example: an oak leaf

Habitat – a forest

Niche – absorb sun, make food, provide shelter for animals, etc.

C. Symbiosis – a close relationship between 2 species; 3 kinds

1. Mutualism - both species benefit(+/+)

A grouper fish gets its mouth cleaned by a goby fish, the goby fish gets food from the

grouper’s mouth

2. Commensalism – 1 species benefits, other is neither

helped nor harmed (+/0)

the clown fish gets shelter, the sea anemone is not helped or harmed

3. Parasitism – 1 species benefits, other is harmed (+/-)

a tapeworm weakens a cow, but

doesn’t kill it

V. Nutrition & Energy Flow

A. Food Chain – route showing how energy flows through autotrophs, heterotrophs, & eventually decomposers in an ecosystem

1. Arrows show the direction of

energy flow:

plant → grasshopper→ mouse → snake

2. Decomposers can break down organisms at any trophic level

3. Usually consists of 2, 3, or 4 transfers

B. Trophic Levels – each feeding step in a food chain or food web

1. 1st order heterotroph - feeds on plants (grasshopper)

2. 2nd order heterotroph – feeds on 1st order heterotroph (mouse)

3. 3rd order heterotroph – feeds on 2nd order heterotroph (snake)

C. Food Web – model showing the many interconnected food chains &

routes in which energy flows through a community

Food Chain song Ecosystem Ecology (CrashCourse)

D. Pyramids

1. Energy, Biomass, & Numbers in each transfer is less than the level before – some energy is used to make new cells or fuel the organisms at that level, some is lost as heat (a byproduct of metabolism)