Autotroph
Heterotroph
Food Web
Energy Flow
Energy Pyramids:
Habitats, Niches,
and Community
Interactions
4.2: 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
Clownfish and sea
anemone
Hummingbird and
Flower
– 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. Density
3. Growth rate
4. Age structure
Factors that affect population size
are:
1. Number of births
2. Number of deaths
3. 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
Populations are limited by
space, food, etc.
Carrying capacity – largest
number of individuals that
a given environment can
support