1. Energy Flow and Populations

2. Autotrophs (Producers)
Flow of Energy in an Ecosystem
Energy in an Ecosystem
Autotrophs (Producers)
Organism that collects energy from sunlight or inorganic substances to produce food
Heterotrophs (Consumers)
Organism that gets it energy requirements by
consuming other organisms
A lynx is a heterotroph.

3. Also known as Detritivores
Flow of Energy in an Ecosystem
and return nutrients
to the soil, air,
and water where
the nutrients can
be reused by
organisms.
Decomposers eat fragments of dead matter in an ecosystem,
Fungus
Also known as Detritivores

4. Food chains and food webs model the energy flow through an ecosystem.
Flow of Energy in an Ecosystem
Models of Energy Flow
Food chains and food webs model the energy flow through an ecosystem.
Each step in a food chain or food web is called a trophic level.
Producers
Primary Consumers
Secondary Consumers
Tertiary Consumers
Tertiary Consumers
Secondary Consumers
Primary Consumers
Producers

5. The length of a Food chains varies with each ecosystem.
Flow of Energy in an Ecosystem
Food Chains
A food chain is a simple linear model that shows how energy flows through an ecosystem.
The length of a Food chains varies with each ecosystem.

6. Food Chains

7. Flow of Energy in an Ecosystem
Food Webs
A food web is a model representing the many interconnected food chains and pathways in which energy flows through a group of organisms.

8. Food Webs

10. 90% of energy is lost as heat 10% is available energy
Flow of Energy in an Ecosystem
Ecological Pyramids
A diagram that can show the relative amounts of energy, biomass, or numbers of organisms at each trophic level in an organism
90% of energy is lost as heat
10% is available energy

11. The number of organisms of a certain species per unit area
Population Dynamics
Population Density
The number of organisms of a certain species per unit area

12. Population Dynamics
Population Ranges
A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region.
Common dolphin
Pupfish

13. Population-Limiting Factors
Population Dynamics
Population-Limiting Factors
There are two categories of limiting factors—density-independent factors and density-dependent factors.

14. Density-Independent Factors
Population Dynamics
Density-Independent Factors
Any factor in the environment that does not depend on the number of members in a population per unit area is a density-independent factor.
Weather events
Fire
Human alterations of the landscape
Air, land, and water pollution

15. Density-Dependent Factors
Population Dynamics
Density-Dependent Factors
Any factor in the environment that depends on the number of members in a population per unit area is a density-dependent factor.
Biotic factors
Disease
Competition
Parasites

16. Population Growth Rate
Population Dynamics
Population Growth Rate
The population growth rate (PGR) explains how fast a given population grows.

17. Exponential Growth Model
Population Dynamics
Exponential Growth Model
Exponential growth occurs when the growth rate is proportional to the size of the population.
All populations grow exponentially until
some limiting factor slows the population’s
growth.

18. Population Dynamics
Logistic Growth Model
The population’s growth slows or stops following exponential growth, at the population’s carrying capacity.

19. Population Dynamics
A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration.

20. Population Dynamics
Carrying Capacity
The maximum number of individuals in a species that an environment can support for the long term is the carrying capacity.
Carrying capacity is limited by the energy, water, oxygen, and nutrients available.

25. Wrap up