1. Ecology Notes

2. Definitions
Ecology: the study of the interactions among organisms and their environment.
Biotic Factors: living parts of the environment (Ex: plants, animals, fungi, etc)
Abiotic Factors: non-living parts of the environment (Ex: temperature, light, pH)

3. Levels of Organization
Organism (Ex: a fish)
Species – a group of the same kind of organism that can successfully interbreed
Population – group of the same species living in the same place
All the red squirrels in a forest
Community – all of the different organisms in a habitat
All of the trees, plants, animals, bacteria in the forest
Ecosystem – includes biotic and abiotic factors
The whole forest, including the river, air, weather

4. Trophic (Energy) Levels in an Ecosystem
Producers – make their own food, like plants
aka: autotrophs (self feeders)
Consumers – obtain energy by feeding on another organism, like animals
aka: heterotrophs (other feeders)
Decomposers – break down dead organisms, like fungus and bacteria

5. Food Chain The path of food transfer from one trophic level to another
Arrows go in the direction of energy flow!

6. Food Chain Video

7. Types of consumers Herbivore – eats only producers
Example: rabbit
Carnivore – eats only other consumers
Example: wolf
Omnivore – eats both producers and consumers
Example: humans
Decomposer – breaks down dead or decaying organic matter
Example: fungi and bacteria
Scavenger – eats whatever it can find, leftovers from already hunted animals, plants, etc
Example: crabs, vultures, and hyenas

8. Food Webs A set of inter-connected food chains
If one organism is removed, all the others will be affected.
If we remove the mouse, then the grasshopper population will rise, but the owl population will decrease

9. Energy Pyramid Video

10. Energy Pyramids
Emphasizes the energy loss from one trophic level to the next. In general, 10% of the energy available at one level is transferred to the next level during feeding.
The remaining 90% is either used by the organisms during its life or it is lost as heat.
90 % Energy
10% Energy

11. Biomass Pyramid - Represents the actual biomass (dry mass of all organisms in each trophic level) in an ecosystem.
Pyramid of Numbers - Depicts the number of individual organisms in each trophic level of an ecosystem
Notice that both usually look just like the energy pyramid

12. Population Growth Human
Exponential Growth - when a population grows with no limits
For instance, the population doubles every 2 years
Graph is in shape of a J –curve
Today, we are adding 82 million people/year,
~ 200,000 per day!

13. Non-native species Grow exponentially
populations introduced to a new habitat out-compete native species
No natural predators or parasites
reduce diversity of habitat
examples
African honeybee
gypsy moth
reduces diversity
loss of food & nesting sites for animals
Cause economic damage
gypsy moth 13

14. Is the human population reaching its carrying capacity?
Logistic Growth
Carrying Capacity – the maximum number of organisms an environment can support
Determined by amount of food, space, or resources
Creates an S-shaped curve
More realistic

15. Predator-Prey Cycles
The size of the predator population limits the size of the prey population and vice versa

16. Species Interactions
Niche – an organism’s “job” or role in the ecosystem
Decomposer
Carnivore
Top predator, etc.

17. Predation (+,-)
One individual (predator) captures, kills, and consumes another (prey)
Predation limits the size of the prey population

18. Examples of predation
Lion and zebra Red-tailed hawk and rodent

19. Competition (-,-) Results from 2 species occupying the same niche
the use of the same limited resource by two or more species

20. Example of competition
Barnacles competing for space
2 carnivores compete for feeding territory

21. Parasitism (+,-)
One individual (host) is harmed, while the other individual (parasite) benefits
Does not usually result in death of host – the parasite would have to go find a new home!

22. Examples of Parasitism
Tick and Human
Flea and Dog

23. Mutualism (+,+) Cooperative relationship where both species benefit
Often species cannot survive as well without each other

24. Examples of mutualism
Rhino and oxpecker
Flower and bee (pollination)

25. Commensalism (+,0)
One species benefits, the other is not affected

26. Examples of commensalism
Cattle Egret and Cape Buffalo
Remora and shark

27. Name that interaction…
Honey guide birds alert and direct badgers to bee hives. The badgers then expose the hives and feed on the honey first. Next the honey guide birds eat. Both species benefit.

28. Mutualism

29. Name that interaction…
Mistletoe extracts water and nutrients from a spruce tree to the tree’s detriment.

30. Parasitism

31. Name that interaction…
Barnacles create home sites by attaching themselves to whales. This relationship neither harms nor benefits the whales.

32. Commensalism

33. Ecological Succession
How a community changes over time
For example from a grassland to a forest
Occurs as one group of species (a community) outcompetes and replaces an older community

34. Stages of Succession

35. Primary Succession No life, no soil before.
Ex. – glaciers melt off of a bare rock
Pioneer species: the first species to colonize an area – usually lichens & moss
Climax community: a mature, stable community with high biodiversity and little change

36. Secondary Succession Already life, already soil
Ex. - Abandoned field , or forest after wildfires
Pioneer species would be weeds and grasses
Secondary happens faster

37. Secondary Sucession (cont.)
Another example is a pond in a forest slowly fills in with silt, becoming a field then eventually a forest
Can you put these pictures in the correct order?

38. Environmental Issues Global Climate Change
Human-caused changes in the ecosystem
Global Climate Change
Caused by excess release of CO2
From burning of fossil fuels
Occurs slowly over many years
Yearly fluctuations in temp are not evidence for or against global climate change

39. Ozone Layer Protects us from harmful UV rays
Has been thinned to dangerous levels
Due to release of CFC’s
From aerosol cans and cooling
Has led to significant increase in skin cancer

40. Acid Rain
Coal-burning plants and cars release nitrogen and sulfur into the atmosphere
Leads to more acidic precipitation (lower pH)
Acid Rain
Normal Rain

41. The End