1. Chapter 18 Sections 1 & 2
Ecology and Organisms

2. Introduction to Ecology
Ecology is the study of the interactions between organisms and the living and nonliving components of their environment.
There is an interdependence that ensures the survival of organisms based on the connections between them.

3. Interdependence and Ecological Models
There are many ways that one organism can depend upon another. Some types of interactions involve feeding, reproduction, disease transfer, and cycling of nutrients. Models can involve building something to scale, predicting patterns using computer simulations or using mathematical algorithms. They help ecologists understand interactions and ecological systems better.

4. Levels of Organization
The broadest level of ecological organization is the biosphere. It is the part of the earth that extends from the deepest depths of the ocean to about 6 miles into the lower atmosphere.

5. Levels of Organization
Within the biosphere are aquatic and terrestrial biomes. Water biomes are distinguished by salinity and water movement. Land biomes are characterized by temperature and precipitation.

6. Levels of Organization
Biomes are not uniform and slight differences in factors results in the next level of organization ecosystems. These are areas that include all organisms & the nonliving environment. Organisms from all 6 kingdoms are included and abiotic factors such as light, moisture, pH, gasses and minerals are present in varying amounts.

7. Levels of Organization
When scientist refer to only the living organisms within an ecosystem this is called a community. Size does not distinguish one from the other. An ecosystem can be as small as a fallen tree and a community can be the forest.

8. Levels of Organization
Communities are comprised of groups of populations of organisms. A population in its strictest sense is defined as a group of individuals that are the same species which can interbreed and live in the same place at the same time.

9. Biotic and Abiotic Factors
Biotic factors are environmental factors that are associated with or results from the activities of living organisms. This includes plants, animals, dead organisms, and the waste products of organisms. Abiotic factors are environmental factors that are not associated with the activities of living organisms which includes air, water, rocks, and temperature.

10. Tolerance Curve
Organisms can only survive within a range of tolerable conditions. For example, if the temperature or water level goes above or below a certain level then their chances of survival go down. A tolerance curve is a graph designed to show this range.

11. Acclimation
Acclimation is a process that allows organisms to adjust their tolerance to abiotic factors. This is something that happens during the lifetime of an organism and is not a genetic change that gets passed on to the next generation.

12. Control of Internal Conditions
Environments fluctuate in temperature, light, moisture, salinity and other chemical factors. Organisms that cannot regulate internal processes and are controlled by these changes are called conformers. Organisms that can use energy to control internal conditions within a range of tolerable environmental conditions are called regulators.

13. Escape from Unsuitable Conditions
There are three ways that organisms can survive unfavorable conditions.
Burrowing or hiding underground to escape heat or predators.
Entering dormancy through hibernation or estivation to escape cold or lack of water.
Migration to a new habitat for a better climate or food resource.

14. Niche
The role of a species in its environment is called its niche. It includes tolerance factors, necessary resources and other environmental interactions.

15. Generalists
Species that have very broad niches and can tolerate a range of conditions are called generalists. These organisms can also use a wide variety of resources in different habitats.

16. Specialists
Species that have narrow niches and rely on specific, limited resources are called specialists. They cannot tolerate a large range of environmental conditions and survive.

17. Interactions in Communities (Read CH20 Section 1)
Competition (- -) = Abundance of BOTH species ↓’s
Predation (+ -) = Abundance of PREDATOR ’s and Abundance of PREY ↓’s
Parasitism (+ -) = Abundance of PARASITE ’s and Abundance of HOST ↓’s
Mutualism (+ +) = Abundance of BOTH ’s
Commensalism (+ 0) = One ’s and One not ∆’ed

18. Competition (- -)
Competition – an interaction between individuals brought about by a shared requirement for a resource in limited supply that leads to a reduction in survivorship, growth, or reproduction of at least some of the competing individuals.
Intraspecific competition involves individuals of the same species.
Sea Anemones, Anthopleura sola are engaged in a war for territory.

19. Competition (- -)
Interspecific competition involves interactions BETWEEN individuals of different species as they compete for the same resources

20. Predation
Predation = an individual of one species (Predator) eats all or part of an individual of another species (Prey) NOTE: Predation is NOT limited to Carnivorous Interactions – The Black Bear is Preying on the Berries!

21. Predation / Natural selection
Predators ADAPT to better CAPTURE Prey! Ex. Teeth, speed, webs, camouflage, etc.
Prey ADAPTS to AVOID being Captured by Predators! Plants can grow Thorns or produce Toxins, etc. Animals camouflage, mimic, or produce toxins, etc.

22. Results of Comp/Pred
Competitive Exclusison = when one species is eliminated from a community because of competition for the same limited resources. The species that utilizes the resources more efficiently thrives!
Ex = 2 Species of Paramecium feeding on yeast!

23. Results of Competition in a Community
Reduced Niche Size! Fig 20-4 Book!
Fundamental Niche = Range of Conditions that it can POTENTIALLY Tolerate and Range of Resources it can POTENTIALLY use!
Realized Niche =Part of Niche that the species ACTUALLY USES
EX = Barnacles (Balanus b. Chthamalus s.)

24. EX = Barnacles (balanus b. Chthamalus s.)
Chthamalus stellatus
Source: A. Southward
Zonation patterns involving barnacles (Connell 1961).
Balanus balanoides
Source: M. Loik
Misted by Tide – only eats during spray/mist
SubmergedEnvironment!

25. High tide Mean tide Low tide Connell’s (1961) barnacles Rocky coast
Scotland
Chthamalus
Balanus
Mean tide
High tide
Low tide
Connell’s (1961) barnacles

26. High tide Mean tide Low tide Connell’s (1961) barnacles Rocky coast
Scotland
Chthamalus
Balanus

27. High tide Mean tide Low tide Connell’s (1961) barnacles Rocky coast
Scotland
Chthamalus
Balanus

28. High tide Mean tide Low tide
Discussion question: How does this Exemplify Realized vs Fundamental Niche?
Why DOESN’T Chthamalus Naturally live in the Mean/Low Tide Area?
Connell’s (1961) barnacles
High tide
Mean tide
Low tide
Rocky coast
Scotland
Chthamalus
Balanus

29. High tide Mean tide Low tide Discussion question:
When Chthamalus is Removed, Balanus DOESN’T survive in the upper levels - WHY?
What stressors might limit Balanus?
Connell’s (1961) barnacles
High tide
Mean tide
Low tide
Rocky coast
Scotland
Chthamalus
Balanus

30. Results of Competition in a Community
Character Displacement = Evolution of Differences in a Characteristic due to competition! Natural Selection favors differences between Competitors, especially when the niches of the competitors overlap!
EX – Chthamalus Evolved to better tolerate Direct Sunlight, Forces of Tide, Salt, etc.

31. Symbiosis – 3 Examples!
Parasitism = when the HOST is harmed and the PARASITE benefits! Note: Favorable to not cause immediate death of host like in a Predator/Prey Relationship
EX. Guinea Worm

33. Symbiosis – 3 Examples!
Mutualism = a relationship in which two species derive some benefit from eachother.
Ex. Ants (Defend Tree from Insect Herbivores with odor and physical attack) and Acacia Tree (Provide Food/Shelter)

34. Symbiosis – 3 Examples!
Commensalism = an interaction in which one species benefits and the other is not affected
NOTE: Some use this term in a general sense and call some mutualisms commensalisms when the BENEFIT for one is not Extremely Significant or Documented!
EX = Barnacles and Gray Whales