1. Ecology 4.1 – 4.2
Eric Molina

2. Species, Communities, and Ecosystems
Species – A group of similar organisms that can
breed and produce fertile offspring
Common gene pool
Populations can become isolated
Isolated species might find itself evolving in a different way compared with the rest of the population

3. Autotrophs & Heterotrophs
Autotrophs – capable of making their own
organic molecules as a source of food
Process involves photosynthesis
Examples of autotrophs
Cyanobacteria
Algae
Grass / Trees

4. Autotrophs
Obtain inorganic nutrients from abiotic (nonliving) environment

5. Autotrophs & Heterotrophs
Heterotrophs – cannot make their own food
from inorganic matter and must
obtain organic molecules from
other organisms
Get chemical energy from autotrophs or other heterotrophs
Examples:
Zooplankton
Fish
Sheep
Insects

6. Consumers
Obtain chemical energy by feeding on the producers or other consumers (heterotrophs)

7. Detrivores Eat non-living organic matter (internal digestion)
Like dead leaves, feces, and dead animals (carcasses)
Earthworms, woodlice, and dung
beetle
Many bottom feeders in rivers, lakes, and oceans are detrivores

8. Saprotrophs Live on or in non living organic matter
They secrete digestive enzymes and absorb the products of digestion (external digestion)
They play an important role in the decay of dead organic materials
Fungi and bacteria

9. Communities
Is formed by populations of different species living together and interacting with each other.

10. Ecosystems Abiotic – non-living components of the environment.
Water, Air, rocks, pH, Light, relative humidity, and temperature
Biotic – Living components of the environment
A community forms an ecosystem by its interactions with the abiotic environment

11. Nutrient Cycling
There is not enough minerals to meet the needs of all the organisms in the biosphere
As a result ecosystems must recycle the carbon, nitrogen, and other elements and compounds necessary for life to exist.
Decomposers – eat waste and remains of dead
organisms
Saprotrophs and detritivores

12. Nutrient Cycling
Nitrogen (N) is found as amino acid in all living things
Although 80 % of Earth’s atmosphere is Nitrogen gas; most organisms can only use Ammonium (NH₄⁺) and Nitric Acid (NO₃⁻)
Decomposers use digestive enzymes and convert the organic matter into a more useable form for themselves and for other organisms
proteins from a dead organism are broken down into ammonia (NH₃) and in turn ammonia can have its nitrogen converted into useful nitrates (NO₃) by bacteria.

14. Nutrient Cycling
Decomposers recycle nutrients so that they are available to other organisms and are not locked inside the bodies or waste products of the ecosystem
Ecosystems have the potential to be sustainable over long periods of time

15. Nutrient Cycling Nitrogen Fixation
Bacteria are able to transform nitrogen into useful forms
Such as nitrates
Usable nitrates are absorbed by plants and then eaten by consumers
Nitrogen is return to the ecosystem in urea and feces

16. Photosynthetic Producers
Plants that convert light energy from sunlight to the chemical energy of organic compounds.
Most ecosystems rely on a supply of energy from sunlight.

17. Energy Flow There are ecosystems that exist in total darkness.
Deep ocean water
Deep underground

18. Photosynthesis
Photosynthetic organisms take simple organic compounds, CO₂, and convert it into energy-rich sugar, C₆H₁₂O₆.
The addition of minerals allows the producers to synthesize complex molecules such as cellulose, proteins, and lipids.

19. The Path of Energy and Chemicals in a Ecosystem
Every organism requires energy to carry out life’s process:
Growing
Moving
Reproducing

20. The Path of Energy
As living things use chemical energy, they release thermal energy (Heat) to the surroundings
Living (most) organisms cannot convert heat to other forms of energy

21. The Path of Energy
Energy is not recycled within an ecosystem, but flows through it and out.
Producers must continue to receive energy so they can transfer that energy; if not the ecosystem could not survive.

22. Food Chains Trophic Level – A feeding level in an ecosystem
Food Chain – the pathway of food transfer from
one trophic level to another
Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels

23. Pyramid of Energy
A pyramids of energy is used to show how much and how fast energy flows from one trophic level to the next in a community.
The units used are energy per unit area per unit of time.
Kilojoules per square meters per year (kjm⁻²yr⁻¹)

24. Pyramid of Energy
Know This : Not This

25. Food Webs
In an ecosystem the feeding relationship is usually more complicated than a simple food chain
Because of the variety of species; animals and
plants
Food Web – the pattern of feeding by
interconnected and branching food
chains