1. 4.1 Species , communities and ecosystems
Topic 4: Ecology
4.1 Species , communities and ecosystems
4.2 Energy Flow
I am the Lorax.
I speak for the trees.
I speak for the trees,
for the trees have no tongues.

2. Ecology
The study of relationships between living organisms and between organisms and their environment
Components:
abiotic~ nonliving chemical & physical factors
biotic~ living factors

3. 4.1 Species, communities and ecosystems
Essential idea: The continued survival of living organisms including humans depends on sustainable communities.
Discuss: what does it mean for a community to be sustainable?
Discuss: Why is sustainability in human activities important and how can this be promoted?

4. What is a Species?
Species: a group of organisms that can interbreed to produce fertile offspring
Members of a species may be reproductively isolated in separate populations.

5. Levels of Organization
Organism- an individual living thing
Population~group of individuals of the same species who live in the same area at the same time.
Community~a group of populations of different species that interact.
Ecosystem~ a community and its abiotic environment
Biosphere– the part of the earth contains all ecosystems

6. Methods of Nutrition
Autotroph: an organism that synthesizes its organic molecules from simple inorganic nutrients in the abiotic environment. Ex. _____
Heterotroph: an organism that obtains organic molecules from other organisms.
Consumer: feeds on living (or recently killed ) organisms by ingestion.
Detritivores~ organism that ingests (and internally digests) non-living organic matter (detritus) ex. Earthworms, maggots.
Saprotrophs -- or decomposers- organisms that live in or on non-living organic matter, secreting digestive enzymes and absorbing the resulting products of digestion. Notice: External Digestion Ex. bacteria and fungi.

7. Trophic Levels
Trophic level~ the position that an organism occupies in a food chain - what it eats, and what eats it.
Primary producers~ the trophic level that supports all others; autotrophs
Primary consumers~ herbivores
Secondary, tertiary… consumers~ carnivores
Food chain~ trophic level food pathway

8. 4.2 Energy Flow
Essential idea: Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.

9. Most ecosystems rely on a supply of energy from ______.
Light energy is converted to chemical energy in carbon compounds by photosynthesis.
A solar prominence erupts in August 2012, as captured by SDO

10. Chemical energy in carbon compounds flows through food chains (and food webs) by means of feeding.
Discuss: what are examples of carbon compounds that have chemical energy?

11. Nature of science
Use theories to explain natural phenomena—the concept of energy flow explains the limited length of food chains. (2.2)

12. Energy released from carbon compounds by respiration is used in living organisms and converted to heat.
Living organisms cannot convert heat to other forms of energy.
Heat is lost from ecosystems.
Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels.

13. Energy Pyramid Quantitative representation of energy flow
Explain shape of the pyramid and be able to draw
Energy transformations = never 100% efficient
Roughly 10% passed to next level
The rest is lost as heat, or not consumed/assimilated
(IB Preferred units:
kJ m-2 yr -1)

14. Biomass in terrestrial ecosystems diminishes with energy along food chains due to loss of carbon dioxide, water and other waste products, such as urea.

15. International-mindedness: The energetics of food chains is a factor in the efficiency of food production for the alleviation of world hunger.
Discuss: What types of organisms should be used for food in order to feed the most people?

16. Flow of Energy vs. Cycling of Matter
Energy enters and leaves ecosystems
Nutrients = recycled (by saprotrophic bacteria and fungi)
The supply of inorganic nutrients is finite and limited but is maintained by nutrient cycling.
Ecosystems have the potential to be sustainable over long periods of time.

17. Skill: Setting up sealed mesocosms to try to establish sustainability
Skill: Setting up sealed mesocosms to try to establish sustainability. (Practical 5)
Mesocosm: small experimental areas set up as an ecological experiment.
Guidance: • Mesocosms can be set up in open tanks, but sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones. •
Many mesocosm ideas
Succession in Pond water lab

18. Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling.
Skill: Recognizing and interpreting statistical significance.
To obtain data for the chi-squared test, an ecosystem should be chosen in which one or more factors affecting the distribution of the chosen species varies. Sampling should be based on random numbers. In each quadrat the presence or absence of the chosen species should be recorded.

19. Take notes on this type of chi-squared test application from: http://ibworld.me/Ecology.html

20. End of IB stuff

21. Food Chain
Be able to describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms)
Hints:
Arrows indicate direction of energy flow
Include producer and consumers
Name organisms at species or genus level: ex. Atlantic salmon (not “fish”)
Use real examples from nature.

22. Food Chain Example

23. Food webs~
More realistic than a food chain
Shows interconnected feeding relationships in an ecosystem
Be able to construct a food web with up to 10 appropriate organisms

24. Some good links on BIOMES and Ecology in general

25. Global climate
Seasons
• Precipitation & Winds

26. Biosphere~the sum of all the planet’s ecosystems
Biome~ areas of predominant flora and fauna
Abiotic factors
Temperature
Water
Sunlight
Wind
Rocks & Soil
Periodic disturbances

27. Terrestrial biomes
Tropical forests~ equator; most complex; constant temperature and rainfall; canopy
Savanna~ tropical grassland with scattered trees; occasional fire and drought; large herbivores
Desert~ sparse rainfall (<30cm/yr)
Chaparral~ spiny evergreens at midlatitudes along coasts
Temperate grassland~ all grasses; seasonal drought, occasional fires; large mammals
Temperate deciduous forest~ midlatitude regions; broad-leaf deciduous trees
Coniferous forest/ taiga~ cone-bearing trees
Tundra~ permafrost; very little precipitation

28. Lake stratification & turnover (SKIP)
Thermal stratification~ vertical temperature layering
Biannual mixing~ spring and summer
Turnover~ changing water temperature profiles; brings oxygenated water from the surface to the bottom and nutrient rich water form the bottom to the surface

29. Marine biomes (SKIP) Intertidal zone~ area where land meets water
Neritic zone~ shallow regions over continental shelves
Oceanic zone~ very deep water past the continental shelves
Pelagic zone~ open water of any depth
Benthic zone~ seafloor bottom
Abyssal zone~ benthic region in deep oceans

30. Aquatic biomes
Vertical stratification: •photic zone~ photosynthetic light •aphotic zone~ little light •thermocline~ narrow stratum of rapid temperature change •benthic zone~ bottom substrate
Benthos~ community of benthic organisms
Detritus~ dead organic matter; food for benthic organisms

31. Freshwater biomes
Littoral zone~ shallow, well-lit waters close to shore
Limnetic zone~ well-lit, open water farther from shore
Profundal zone~ deep, aphotic waters
Lake classification: •oligotrophic~ deep, nutrient poor •eutrophic~ shallow, high nutrient content
•mesotrophic~ moderate productivity
Wetland~ area covered with water
Estuary~ area where freshwater merges with ocean