Ecosystems and communities
Weather and Climate

Weather
 Day-to-Day

variations in conditions
Climate
 Year-after-Year
 Factors
patterns of temperature and precipitation
that affect CLIMATE?
The Greenhouse Effect

Greenhouse Gases


Carbon Dioxide, Methane, Water Vapor, CFCs
Why is this important?
Where do Organisms Live?

Tolerance: the range of conditions under which an organism can survive and
reproduce.

Habitat: the general place where an organism lives

Niche: An organism’s role in an ecosystem, including how it interacts with
biotic and abiotic factors, plus the resources it uses
Competition in Ecosystems


Definition: When organisms attempt to use the same
resource

Intraspecific – between members of the same species

Interspecific – between members of different species
Competitive Exclusion Principle

No two species can occupy exactly the same niche at the
same time

If two species attempt to occupy the same niche at the same
time, one will lose out
Predation and Herbivory

Predation: One animal (predator) captures and feed on another
animal (prey)

Herbivory: One animal (herbivore) feeds on primary producers
(i.e. plants)

*BOTH affect the population size and distribution of what is
eaten
What is going on here??
Keystone Species

Definition: A species that can cause dramatic changes in
ecosystem and/or community structure
Symbiosis

Definition: Relationship in which 2 organisms live closely
together

Types: Mutualism, Parasitism, Commensalism

Mutualism: Both organisms benefit

Parasitism: One organism benefits and the other is harmed

Commensalism: One organism benefits and the other is unaffected
Is it Mutualism, Parasitism, or Commensalism?
Clownfish and Sea Anemone
Whale and Barnacles
Tick and Human
Caterpillar and Wasp (larvae)
Ants and Acacia
Populations
Describing Populations

Geographic Range: Area inhabited by population

Density: Number of individuals per unit area

Distribution: How individuals are spaced within a population

Random
Uniform
Clumped

Growth Rate: population numbers changing

Age Structure: Number of males and females of each age

Why is this important?
Random, Uniform, or Clumped??
Population Growth Rate

What factors affect growth rate??
 Birthrate
 Death
rate
 Immigration
 Emigration
Exponential Growth


Definition: The larger a population gets, the faster it
grows
When does this occur?

Under ideal conditions, unlimited resources
Logistic Growth

Definition: When a population’s growth slows and then
stops, following a period of exponential growth.
 Carrying
Capacity: The maximum number of individuals
of a species that a particular environment can support
Limiting Factors

Definition: Factors that control the growth of a population and
determine the carrying capacity

Density-Dependent Factors: Affect populations
significantly only when population reaches a certain size

Density-Independent Factors: Affect all populations in
similar ways, regardless of size and density