Download Chapter 14 Interactions in Ecosystems

Interactions in
Ecosystems
Chapter 14
Every organism in the biosphere lives
in a given habitat. The address
The conditions that must exist for
it to live within it’s habitat is the
niche.
Resource availability determines
the structure of a community
Resource Partitioning
Increases
Biodiversity
Competitive Exclusion Principle
Two living separately okay,
living together one will cause the other to go extinct
Species interactions defines
the role and success of each
organism within the biosphere
Predator Prey Interaction
What factors effect predator-prey relationships?
Symbiosis- three forms
1. Mutualismthey both
benefit!
Lichen- fungus and an algae, fungus provides the
home, algae provides the food, pioneer organism
Symbiosis continued…..
2. Commensalism
one benefits the other is
neither helped nor harmed
3. Parasitism-
one
benefits, the other is
harmed
There are two types of population
growth curves
Exponential growth- J curve
Human Population Growth
Overshoots
carrying capacity,
does not respond
to limiting factors,
can cause a sudden
die off
Our population is currently 6.7 billion people
We reached 6 billion in August 1999
Logistic Growth- S curve
Curve found in
nature where
species population
is held in check by
limiting factors.
Limit of population
is called the
carrying capacity,
fluctuates with
climatic changes
Limiting Factors
factors that hold a population in check
Density-Independent factors
Will kill everyone no matter what the density is
Earthquakes, floods, volcanic eruptions
Density-Dependent factors
Increase as the population of species increases
Competition, predation, disease
P= (B + I) – (D- E)
P= population
B= births
I= immigration
D= death
E= emigration
Survivorship Curvesdescribe the life history of a species
Type I
few young
take care of
young for a
long period of
time
Type III
no care of
young, they
become
part of the
food chain
Type II
Have equal chances of
living or dying
Primary Succession
There is no
soil
Secondary Succession
A disturbed environment
Begins
with
weeds
Fire Succession
A form of secondary succession
Many plant communities depend upon fire
to germinate seeds and maintain health