Download Chapter 4: Ecosystems and Communities

Chapter 4: Ecosystems and Communities
A. Effects on the Ecosystem:
1. Limiting Factor: biotic and abiotic factors that restrict or limit
the number of organisms that inhabit and area
Ex. Biotic: food, predators, prey, autotrophs, competition
Abiotic: space, water, sunlight, salt, oxygen,
temperature (altitude/latitude)
2. Carrying Capacity: the maximum number of organisms an
area can “hold” on a sustained basis
 Organisms grow exponentially (reproduce at a high
rate) until the limiting factors keep them at the
carrying capacity
3. Biodiversity: all of the different types of life that exist in an
area
 The more biodiversity (variety of life) the more stable
(unchanging) the environment is
 More biodiversity means limiting factors will not affect
an area as much as an area with a single population
B. What Shapes and Ecosystem?
1. Niche: the role or occupation an organisms has in the
environment
Ex. Bee=pollinator, lion=predator, algae=photosynthesis
 Organisms with the same niche wind up competing
 Some will die, have to move, or develop new
adaptations
 The niche is mostly how organisms obtain food
2. Habitat: the place in the ecosystem where an organisms lives
out its life
Ex. Worm=dirt, bird=tree in forest, polar bear=arctic
3. Community Interactions:
a. Predation: organisms that kill for food (prey)
b. Symbiosis: a relationship in which 2 species live
closely together
1. Mutualism: both species benefit from the
relationship (+,+)
Ex. Bee and flower
2. Commensalism: one species benefits but
the other is neither harmed nor benefits
(+,0)
Ex. Barnacle on a whale
3. Parasitism: one species benefits, the other
is harmed, (+,-)
 Parasite/host relationship
 If the host dies the parasite dies
Ex. Tapeworm, tick, flea, leech,
mosquito
C. Ecological Succession
1. Succession: a change in the environment over time due to
a disturbance
 As long as the climate stays the same the
environment will return to its previous condition
after many years
 As the types of autotrophs change the heterotrophs
change as well
 The more soil that is created the large and more
deep-rooted the vegetation becomes
a. Pioneer Species: first organisms to inhabit a new
area
 Cling to and crush the rock to create a thin
layer of soil
Ex. Lichens and moss
b. Climax Community: the environment continues to
change until it becomes stable and mature
(biodiverse)
c. Self-sustaining Ecosystem: the environment takes
care of itself
 No outside influence is needed to maintain it
 Ecosystem has a constant source of energy
and has a lot of biodiversity
d. Causes for Succession:
 Volcanic eruption, floods, fires, hurricanes,
tornadoes
D. Biomes
1. Biome: many ecosystems that share the same characteristics
and climax communities
 Determined by climate (altitude/latitude)
 Usually named after the significant autotroph
population
a. Aquatic Biome:
 Most stable biome due to its ability to hold heat
and relative size
 Has the most autotrophs
1. Estuaries: body f water containing fresh and
salt water
 Organisms must have a high tolerance for
the changing salt concentrations
Ex. Mississippi River and Gulf of Mexico
2. Photic Zone: portion of the marine biome where
light penetrates
 Complete food chain (autotrophs present)
3. Aphotic Zone: portion of the ocean that does not
receive light
 Only find predators, scavengers, and
decomposers that feed on the remains
other organisms or the remain from the
photic zone
4. Intertidal Zone: portion of the shoreline that is
covered during high tide but exposed
during low tide
 Organisms must have adaptations to
survive in this harsh environment
 Limiting factors: waves, rock