Notes: Ecosystems and Communities Pre-AP
Habitat- __________________________________________________________________________
Niche- ___________________________________________________________________________
_________________________________________________________________________________
Competition- ___________________________________________________________________
 Interspecific competition: _______________________________________________________
_________________________________________________________________________



Intraspecific competition: _______________________________________________________
___________________________________________________________________________
Competitive exclusion _________________________________________________________
o One species is better suited to the niche and the other will either be pushed out or
become extinct.
o The niche will be divided.
o The two species will further diverge.
Ecological Equivalents ________________________________________________________
___________________________________________________________________________
Predation- ________________________________________________________
Ex: lion eats a deer
1. Mutualism- _______________________________________________________________
Ex. ant live on an acacia tree, ant protects tree from harmful plants, tree gives ant a home
2. Parasitism- ______________________________________________________________
Ex. Fleas or ticks on a dog; flea gets a home, sucks the dog’s blood and is bothered by it
3. Commensalism- __________________________________________________________
Ex. moss growing on trees
4. Symbiosis- ________________________________________________________
Symbiotic Relationship
Mutualism
Parasitism
Commensalism
+: benefit
-: harm
Species A
Species B
0: neutral
Population Density - _______________________________________________________________
Population Dispersion- _____________________________________________________________
 Clumped____________________________________________________________________
 Uniform_____________________________________________________________________
 Random____________________________________________________________________
Logistic Growth
Exponential Growth
Factors Affecting Populations
Four things affect population size:
 ___________________________________
 ___________________________________
 ___________________________________
 ___________________________________
Types of Growth
 ________________________- if a population has abundant space and food, no disease or
predators; it will grow at an exponential rate. It is a J-shaped curve resembling y = ax2 + b

_________________________- population growth slows then stops (stays stable) after a
period of exponential growth once resources become less available. The number at which the
environment can support this population is known as the carrying capacity.
Limiting factor- factor that causes a population to decrease in size
 Density dependent- _________________________________________________________
___________________________________________________________________________
Notice the pattern of population size with predator/prey relationship of wolves and deer

Density independent_________________________________________________________. Unusual weather,
natural disasters, seasonal cycles, and certain human activities
Succession- ______________________________________________________________________
o After such disasters, a community can start anew by a process called ecological
succession (series of predictable changes that occurs in a community over time); there
are two types
 Primary succession- __________________________________________
(after a volcanic eruption/ glacier retreats)
 Secondary succession- _________________________________________
(after a fire, disease, natural disaster
Marine Succession
•

•
Stage 1
– Begins when a large whale dies and sinks to the ocean floor
– Attracts scavengers and decomposers (hagfish, sharks, crabs, shrimp), which eat the soft tissue
Stage 2
– After 1 year, most of the soft tissue has been eaten
– Decomposition of the body enriches the sediment with nutrients, which attracts fish, crabs, and
many marine snails and worms
Stage 3
– Begins only when the skeleton remains
– Bacteria decompose the oils inside the bones
– The bacteria support a community of mussels, marine snails, marine worms, crabs, and clams