Download Ecosystems and Communitiesthird class

ECOSYSTEMS AND
COMMUNITIES
• Learning Goal: In this lesson we will learn
about abiotic and biotic components of an
ecosystem. We will also learn about how
populations interact with other populations
within their communities.
BIOTIC VS. ABIOTIC FACTORS
Biotic factor: living component of an
ecosystem
Abiotic factor: nonliving component
of an ecosystem
Can you list abiotic and biotic
factors in this picture?
HABITAT VS. NICHE
Habitat: the area where an
organism lives, including the biotic
and abiotic factors that affect it
Niche: an organism’s habitat plus
its role in an ecosystem
COMMUNITY INTERACTIONS
Competition: when organisms of the
same or different species attempt
to use an ecological resource at the
same time
Example: in a forest, broad-leaved
trees may compete for sunlight by
growing tall, spreading out their
leaves and blocking sun to shorter
plants
Competitive exclusion principle: no two species
can occupy the same niche at the same time
COMMUNITY INTERACTIONS
Predation: an
interaction in which
one organism
captures and feeds
on another
organism
Example: Some
types of bears
capture and eat
fish
COMMUNITY INTERACTIONS
Symbiosis
Parasitism: symbiotic
relationship in which
one organism
benefits while the
other is harmed
Example: fleas, ticks
and lice feed off
the blood and skin of
mammals
COMMUNITY INTERACTIONS
Symbiosis
Mutualism: symbiotic
relationship in which
both organisms
benefit
Example: oxpeckers
eat the insects off
large mammals in
Africa
Cleaner wrasse
COMMUNITY INTERACTIONS
Symbiosis
Commensalism: symbiotic relationship in
which one organism benefits while the
other is neither harmed nor does it
benefit
Example: Remoras eat the small pieces
of food that are created when sharks
eat
Shark and a remora
A whale with barnacles
POPULATION
GROWTH
Exponential Growth:
rapid period of
growth that occurs
under conditions with
unlimited resources
Logistic Growth: when
a population’s growth
slows or stops after a
period of exponential
growth.
How might this happen?
Limiting factors: factors that limit the
growth of a population
 Food
 Sunlight
 Water
 Dissolved oxygen
 Nutrients in soil
 Disease
Carrying capacity: the largest number
of organisms that an environment can
consistently support