1. MicroEcology: Small Scale Relationships
Essential Questions:
What are the relationships between organisms?
What are the relationships between many organisms?
What factors influence these various relationships?

2. Recap
What happens to the amount of energy available as it moves up the trophic levels?
According to the 10% Rule, only 10% is passed on. The spent 90% is metabolized, stored or lost as heat.

3. How do Organisms Obtain Energy?
Some organisms are Producers that make their energy from the sun.
They are called autotrophs.
Some organisms are consumers that make their energy by consuming producers.
They are called heterotrophs.
THE BIG IDEA:
light E (sun)  chemical E (sugars)  useable E (ATP)

4. But what about the organisms that don’t have access to sunlight
Some organisms rely on the energy stored in inorganic chemical compounds.
-Example:Tube worms rely on the under sea vents to survive

5. How do we show individual relationships?
We can do this by examining how organisms interact with each other in order to understand the larger picture of all interactions.
Symbiosis – close and permanent relationship between organisms of same/different species.
There are 5 main types of symbiotic relationships.
Mutualism, Predator/Prey, Commensalism, Parasitism and Competition.
These relationships evolved due to various selectional pressures.

6. 1. Mutualism
Relationship in which both species profit from their interaction.
Example:
Birds and Crocodiles.
Ants and Acacia Trees.
Benefit: + and +
Significance: Have evolved or even co-evolved (under selectional pressure) for mutual survival, the most typical type of symbiotic relationship.

8. 2. Predator / Prey Relationship
Predators – animals that hunt and kill other animals.
Prey – animals that predators eat.
Example: Rabbits & Foxes
Benefit: + and +
Significance: Beneficial to both populations since predators keep prey numbers below their carrying capacity and the amount of prey limits the number of available predators. Natural check and balances for populations.
Interpreting Diagrams: What might happen if there was a sudden change in the rabbit habitat? What about the Fox Population?

11. 3. Commensalism
One species benefits and the other species is neither benefited nor harmed.
Example: Cattle Egrets and Cattle
Benefit: + and 0 (null)
Significance: Likely evolved to the issue of habituation to non-threatening species. Many commensal relationships may stray into mutualistic arenas.
Cattle while grazing disturb insects that the egrets swoop in and eat.

12. 4. Parasitism
One species benefits (the parasite) at the expense of another (the host) causing them harm.
Example: Fleas on a Dog
Benefit: + and -
Significance: Parasites exhibit a high degree of specialization for their mode of life, reproduce at a faster rate than their hosts, and have evolved to response to the defense systems of their hosts.
Often omitted, they occupy the highest level of dominance in food webs.

13. 5. Competition
an interaction between organisms or species, in which the fitness of one is lowered by the presence of another.
Due to the competition over a limited resource like habitat, food and/or mates.
Example: exotic species and native species, competing males
Between the same species is called intraspecific competition
Between different species is interspecific competition.
Benefit: - and -
Significance: According to the competitive exclusion principle, species less suited to compete for resources should either adapt or die out. In evolution, competition within and between species for resources plays a critical role in natural selection (survival of the fittest.)
Strategies to reduce interaction include geographic isolation, niche adaptations, etc.

14. Creation of Niches helps reduce competition.

15. Wait, What is a Niche?
An organism’s occupation within their habitat (Where they live)
A range of physical and biological conditions in which an organism lives and uses the conditions.
The combination of biotic (Living) and abiotic (non-living) factors in an ecosystem often determines how many niches there are.
What they eat, physical conditions they require, how and when it reproduces
Example: Your niche is being a student.
Example: Our habitat is…

17. Displaying Data: Food Chains
Food Chain – model to show how energy and matter move through an ecosystem.
Drawn with arrows that show the movement of energy from one level to another.
Each level is called a trophic level.
Always starts with a producer.
Each consumer that follows is named primary, secondary, tertiary consumer…
Ends with the top carnivore or highest level consumer.
Note there are many ways energy can move through a system!
Only shows one particular feeding relationship.
What type of consumer is the Caterpillar?
The Snake?
Herbivore!
Carnivore!

19. Food Chain
Where are the producer, primary, secondary and tertiary consumers?
Primary Consumer
Secondary Consumer
Tertiary Consumer
a.k.a. The Top Carnivore!
Producer

20. Displaying Data: Food Webs
Food webs – shows all the possible feeding relationships at each trophic level in a community of organisms.
Think of it as a summation of all possible food chains.
Going Further:
What other factors could affect this particular food web?
Global food webs?