Autotroph Heterotroph

Food Web

Energy Flow

Energy Pyramids:

Habitats, Niches, and Community

Interactions4.2: Pg. 90-93

Biotic and Abiotic Factors

• Ecosystems are influenced by a combination of biological and physical factors

• Biotic Factors: the biological influences on organisms

• Abiotic Factors: Physical, or nonliving, factors– i.e. temp, precipitation, humidity, wind,

nutrient availability, soil, sunlight, etc.

Habitats and Niches• Habitat: the area where an

organism lives. Includes both the biotic & abiotic factors

• Niche: the full range of physical & biological conditions in which an organism lives & the way in which the organism uses those conditions

Niche includes…• Place in the food web• Range of temp. organism needs to

survive• Type of food organism eats• How it obtains food• Who uses the organism for food• Physical conditions required to survive• When & how organism reproduces

Competitive Exclusion Principle

• No two species can share a niche in the same habitat!!...example is the Warblers…

Warbler Niches Each of these warbler species has a different niche in its spruce tree habitat. By feeding

in different areas of the tree, the birds avoid competing with one another for food.  

Community Interactions

• Community interactions, such as competition, predation, and various forms of symbiosis can powerfully affect an ecosystem.

Competition• Competition: occurs when organisms

of the same or different species attempt to use a resource at the same place and time.

Trees in competition for light

Predation• Predation: one organism captures

and feeds on another

Lynx and Hare

Symbiosis• Symbiosis: Any relationship in which

two species live closely together– Mutualism: both species benefit

Hummingbird and Flower

Clownfish and sea anemone

– Commensalism: one species benefits, other neither harmed nor helped

Barnacles on a whale

– Parasitism: one organism lives in or in another & harms it

A flea or tick feeds on the blood of its host and may also carry disease-causing microorganisms Mistletoe in a

tree

Characteristics of Populations

5.1 pg. 119-122

Characteristics of Populations are:

1. Geographic distribution (area inhabited by population)

2. Density3. Growth rate4. Age structure

Factors that affect population size are:

1. Number of births2. Number of deaths3. Number of individuals that enter or

leave population• Immigration – move in • Emigration – move out

• If a population has abundant space and food and is protected from predators & disease, then organisms will multiply and the population will increase.

Exponential growth occurs when the individuals of a population reproduce at a constant rate.

J-shaped Curve – Exponential growth

Occurs under ideal conditions with unlimited resources

(Has not reached its carrying capacity)

S-shaped curve – Logistic Growth

Carrying capacity – largest number of individuals that a given environment can support

Populations are limited by space, food, etc.