1. CHAPTER 2
PRINCIPLES OF ECOLOGY

2. ORGANISMS AND THEIR RELATIONSHIPS
Main Idea for Ch. 2.1:
Biotic and abiotic factors interact in complex ways in communities and ecosystems.
Discussion:
Who or what do you depend on?

3. ECOLOGY
Ecology is the scientific area in which the relationships among living organisms and the interactions the organisms have with their environments are studied.
Scientists who study ecology are called ecologists.
Ecologists perform tests in the environment where organisms live to find out why they die or live, grow in number or decrease, live in water or near the water, etc.
Ecologists use models so they can test in a lab things that are happening in the environment.
Models help scientists control the variables and study them one at a time.
EX: more or less water, more or less light, temperature changes, etc.
Helps scientists completely understand the effects taking place in the environment.

4. Which task would be completed by an ecologist?
Discussion:
Which task would be completed by an ecologist?
Survey and classify mollusk fossils
Inoculate cattle against infection
Test the effect of cyanide on algae
Explore the medicinal uses of nectar
What are some locations where you might find ecologists collecting data, and what tools might they use in these locations?
What types of organisms have you ever observed or collected that live near your home?
What are some interesting characteristics of these organisms?

5. THE BIOSPHERE Biosphere is the portion of Earth that supports life.
The prefix “bio” means life.
Includes: surface of earth, atmosphere, oceans, lakes, and extends down several kilometers below the surface to any location that includes life.
EX:
Rainforest Desert Marine Life
Ecologists study these organisms, their adaptations, and the factors in their environments.
These factors are divided into 2 large groups.
Living factors – biotic
Nonliving factor - abiotic

6. BIOTIC FACTORS
Anything living in an organism’s environment are called biotic factors.
The interactions among organisms are necessary for the health of all species in the same geographic location.
What are some of the biotic factors in this picture and how do they relate to one another.

7. ABIOTIC FACTORS
Nonliving factors in an organism’s environment are called abiotic factors.
Abiotic factors include:
Temperature
Air
Water
Sunlight
Soil types
Rainfall
Nutrients
Organisms depend on abiotic factors to survive.
Organisms have adaptations to live with certain abiotic factors. If the abiotic factors change organisms need to change or they will die.
Argument: Oxygen is the only abiotic factor that allows you to survive in this classroom. So, as long as there is enough oxygen, all of you will survive.

8. LEVELS OF ORGANIZATION
Levels of organization increase in complexity as the numbers and interactions between organisms increase.
Levels of organization are:
Organism
Population
Biological community
Ecosystem
Biome
Biosphere

9. ORGANISMS, POPULATIONS, AND BIOLOGICAL COMMUNITIES
Organism – is one individual
Population – is a single species that share the same geographic location at the same time.
Individual organisms in the population compete for the same resources. If the resources are high, the population will grow. If not, the population will decrease. Eventually the population #’s will match the resources for the area.
Biological community is a group of interacting populations that occupy the same geographic area at the same time.
Different populations may or may not compete for resources.

10. ECOSYSTEMS, BIOMES AND THE BIOSPHERE
Ecosystem is a biological community including the abiotic factors that affect it.
Ecosystems can be large or small
Biome is a large group of ecosystems that share the same climate and have similar types of communities.
Biosphere contains all of the biomes on Earth and is the highest level of organization.

11. ECOSYSTEM INTERACTIONS
Survival of the different populations increases if they use the resources in different ways.
EX: birds use different areas of the tree to build nests.
Habitat is an area where an organism lives.
EX: deer covering 5 sq. miles to find food.
Niche is the role or position that an organism has in its environment (habitat).
EX: food, shelter, and reproduction
Discussion:
What is an example of a habitat and an individual’s niche in that habitat?

12. COMMUNITY INTERACTIONS
Interactions in the community include competition for basic needs like food, shelter, mates, and how organisms depend on each other for survival.

13. COMPETITION
Competition occurs when more than 1 organism uses the resource at the same time.
The organism that out competes the other one is the one that survives.
PREDATION
Predation is when one organism pursues and eats another organism for food.
Predator is the organism that is doing the pursuing.
Prey is the organism that is caught and ate.
EX: mallard duck eating water bug.

14. SYMBIOTIC RELATIONSHIPS
Symbiosis is the close relationship that exists when 2 or more species live together.
There are 3 different types of symbiosis:
Mutualism
Both organisms receive a benefit
EX: flowers and bees
Commensalism
One organism receives a benefit & the other one is not hurt or harmed
EX: clownfish and sea anemones
Parasitism
One organism receives the benefit & the other one is hurt or dies.
EX: Fleas, ticks, tapeworms, etc.

15. Section 2.2
FLOW OF ENERGY IN AN ECOSYSTEM
Autotrophs capture energy, making it available for all members of a food web.
The sun is the original source of energy!

16. ENERGY IN AN ECOSYSTEM
Organisms differ in how they obtain energy. They are either autotrophs or heterotrophs.
AUTOTROPHS
Autotrophs are organisms that collect energy from sunlight or inorganic substances to produce food.
EX: plants, bacteria
Autotrophs are the foundation for all organisms in an ecosystem
Autotrophs are also called producers
Discussion: What is the process by which autotrophs convert light energy into chemical energy?

17. HETEROTROPHS
Heterotroph is an organism that gets energy by consuming other organisms.
Heterotrophs are also called consumers.
Different types of consumers:
Herbivore – only eats plants, EX: rabbit, cow
Carnivores – only eat meat, EX: wolves, lions
Omnivores – eat both meat & plants, EX: humans, bears
Detritivores - eat fragments of dead matter in an ecosystem and return nutrients back to the soil, air, and water where the nutrient can be recycled by other organisms. EX: worms
Decomposers (similar to detritivores) – break down dead organisms by releasing digestive enzymes. EX: fungi (mushrooms), bacteria

18. MODELS OF ENERGY FLOW
Ecologists use food chains & food webs to model the energy flow through an ecosystem.
A trophic level is a step in a food chain or web.
Autotrophs make up the first trophic level in all ecosystems.
Heterotrophs make up the remaining levels.

19. FOOD CHAINS
Food chain is a simple model that show how energy flows through an ecosystem.
In a food chain the energy ONLY flows in one direction, up the tropic levels.
The arrows show what direction the energy flows, which usually starts with the autotrophs and moves to the heterotrophs.
Some of the energy is not transferred from one trophic level to the next because it is used by the organism for new cells & tissues.

20. FOOD WEBS
A food web is a model representing the many interconnected food chains and pathways in which energy flows through a group of organisms.

21. ECOLOGICAL PYRAMIDS
An ecological pyramid is a diagram that shows the relative amounts of energy biomass or numbers or organisms at each trophic level in an ecosystem.
Energy pyramid only 10% of the energy is transferred to the next level.
The organism uses 90% of the energy for bodily processes or released as heat.
Biomass pyramid shows the amount of total mass of living matter at each trophic level
Pyramid of numbers shows the number of organisms at each trophic level

22. SECTION 2.3
CYCLING OF MATTER
Essential nutrients are cycled through biogeochemical processes.
Discussion:
What would happen if matter was bound in living matter and never recycled?

23. CYCLES IN THE BIOSPHERE
Energy is transformed into usable forms to support life of an ecosystem.
Constant supply needed so matter needs to be recycled.
Matter is anything that takes up space and has mass.
Nutrient is a chemical substance that an organism must obtain from its environment to sustain life and to undergo life processes.
Biogeochemical cycle is the exchange of matter through the biosphere.
Bio means life, geo means earth, & chemical
Producers (plants) use air, soil and water to convert them into usable nutrients. Consumers eat the plants & the nutrients are passed to them. Decomposers will return the nutrients to be recycled.

24. WATER CYCLE
Water is constantly evaporating off of bodies of water & go up into the atmosphere in the form of water vapor.
90% of all evaporation occurs over the ocean, lakes and rivers.
10% evaporates from plants through a process called transpiration.
Water vapor creates clouds & then precipitation.
Ends up on the surface & is soaked up by plants or remains underground. Can fall in lakes or streams & return to ocean

25. THE WATER CYCLE - CONTINUED
Organisms cannot live without water.
3% of all water on Earth is fresh. 69% of all fresh water is either frozen in glaciers or underground.

26. THE CARBON AND OXYGEN CYCLES
All living things are composed of molecules that contain carbon, such as protein, carbohydrates and fats.
Carbon and oxygen make up molecules essential for life, including carbon dioxide and simple sugars.
In photosynthesis, plants and algae, will convert carbon dioxide + water into carbohydrates + oxygen for the atmosphere.
These carbohydrates are used as a source of energy for all organisms in the food web.
Carbon dioxide is recycled back into the atmosphere through cellular respiration. (You do cellular respiration)
Carbon can be stored for long periods of time as fossil fuels & released when burned, adding carbon dioxide to the atmosphere.

27. Discussion:
Based on your understanding of the carbon cycle, predict what might happen if large areas of tropical rain forest continue to be cleared.
How do you interact in the carbon cycle?

28. Largest amount found in atmosphere.
THE NITROGEN CYCLE
Nitrogen is an element.
Largest amount found in atmosphere.
Can’t be used by plants and animals in this form
Nitrogen fixation occurs when bacteria convert the nitrogen gas to nitrates.
Enters food web when plants absorb nitrogen compounds from the soil & convert them into protein.
Nitrogen is often a limiting nutrient for the growth of producers.
Decomposers will return nitrogen in protein back into ammonia.
Denitrification occurs when bacteria convert the nitrogen compounds back into nitrogen gas returning it to the atmosphere.

29. NITROGREN CYCLE

30. THE PHOSPHORUS CYCLE
Phosphorus essential for growth & development of organisms.
Short term cycle:
Soil →producers →consumers
Decomposers return phosphorus to soil
Long term cycle:
Stored in sedimentary rocks
Released through weathering or erosion
Phosphorus is a limiting nutrient.