ECOLOGY: the study of how organisms interact with each other and their environment

1. ECOLOGY: the study of how organisms interact with each other and their environment • Specifically, how organisms: • get energy • avoid being energy for another organism • use energy to reproduce, so there are always organisms of that species on earth

2. Ecologists have developed a series of nested categories to organize all the organisms on the planet. Nested means smaller categories fit inside larger ones.

3. These categories are called ‘Levels of Organization’ The next slides illustrate the categories from large to small

4. BIOSPHERE: all the places on the planet where life is found (including decomposing remains of organisms) • Extends from the deepest parts of the ocean (≈ 8 km) to ≈12 km above the surface • Includes all organisms, from bacteria to giant sequoia trees and blue whales This thin blue line is the extent of earth’s biosphere

5. BIOME: a region of the earth with similar climate (temperature and rainfall) and similar types of organisms

6. ECOSYSTEM: a collection of all organisms in a particular place and the non-living parts of the environment

7. COMMUNITY: all the organisms living in an ecosystem

8. POPULATION: all the individuals of a species living in an ecosystem

9. INDIVIDUAL: one member of a species

10. REMEMBER…the Levels of Organization are nested!!

11. All organisms need energy and matter • To fuel daily activities • To build the molecules that make up their bodies

12. Energy flows through ecological communities in one direction Each level of energy flow uses most of the energy for activities and a small part for growth and repair of body parts

13. The majority of earth’s ecosystems are fueled by the sun • Plants absorb the sun’s energy and convert it to chemical potential energy stored in sugar molecules • Plants are called: • Producers because they produce molecules that store energy • Autotrophs because they don’t rely on other organisms for energy or molecules • PRODUCERS are the first stop as energy flows through ecosystems

14. All other organisms consume other organisms for energy and are called CONSUMERS (aka heterotrophs) • There are several levels of consumers • HERBIVORES: eat plants (producers/autotrophs) • CARNIVORES: eat animals • 1st level carnivores eat herbivores • 2nd level carnivores eat other carnivores • And so on • OMNIVORES: eat plants and animals • DETRITOVORES/DECOMPOSERS: breakdown dead organisms and return materials to the abiotic environment • EACH OF THESE LEVELS IS CALLED A TROPHIC LEVEL

15. Ecologists use diagrams to illustrate flow of energy and matter through ecosystems. • Food Chain • Food Web • Energy Pyramid • Biomass Pyramid • Numbers Pyramid • Each of these diagrams focuses on a different aspect of how ecosystems function

16. FOOD CHAIN: a diagram that shows one set of energy transfer relationships in an ecosystem

17. FOOD WEB: a diagram that shows all the feeding relationships in an ecosystem

18. Food Webs can get complicated!

19. In both Food Chains and Food Webs, arrows show the direction of energy movement, starting with the _________ .

20. ENERGY PYRAMID: a diagram that shows how much energy is present in each trophic level of an ecosystem The volume of each level of the pyramid represents how much chemical energy is stored in biological molecules

21. BIOMASS PYRAMID: a diagram that shows how much living matter is present at each trophic level

22. PYRAMID OF NUMBERS: a diagram that illustrates the number of individuals in each trophic level

23. Some important definitions: Abiotic – non-living Biotic – living Nutrient – a substance that contains an element needed by an organism to build molecules that does not contain chemical potential energy

24. In addition to energy, organisms need certain atoms to build biological molecules. • Proteins contain nitrogen • Nucleic Acids contain phosphorous • All organic (biological) molecules contain long chains or rings of carbon • Most organisms are about 70% water • Organisms obtain these atoms or compound from the abiotic environment • These substances move between the biotic and abiotic environments • These cycles that move nutrients between the abiotic and biotic environments are called: • BIOGEOCHEMICAL CYCLES

25. BIO: GEO: CHEMICAL: CYCLE: Know the definition of this term

26. There are 4 main biogeochemical cycles: • Carbon • Nitrogen • Phosphorous • Water Abiotic Environment Biotic Environment

27. CARBON CYCLE

28. CARBON CYCLE: • Begins with CO2 in the atmosphere • Plants convert carbon in CO2 to carbon in sugar during photosynthesis • Food molecules move through food web, being: • Converted to energy • Made part of a new organism • CO2 returned to atmosphere as molecules are broken down for energy • Cycle begins again as CO2 taken up by plants

29. PHOSPHOROUS CYCLE

30. PHOSPHOROUS CYCLE: • Eroding rocks make phosphorous available to organisms • Plant roots absorb phosphorous from the soil; the plant then uses it to build DNA and RNA • The phosphorous moves through the food web • Phosphorous returns to the abiotic environment as dead organic material decomposes

31. NITROGEN CYCLE

32. NITROGEN CYCLE: • N2 gas is part of atmosphere • Nitrogen fixing bacteria in soil, and living symbiotically on the roots of bean and pea plants remove N2 from the atmosphere and convert it to nitrate (NO3) • plants take up and use the NO3 to make proteins • Nitrogen moves through the food web, some is eliminated as waste • De-nitrifying bacteria in the soil convert nitrogen in waste and decomposing organisms in N2 gas, which returns to the atmosphere

34. The water cycle moves water all around the planet and is vial to life because it allows rain to fall so: • Soil can be moist for plants • Lakes, rivers and streams can flow • But a small part of the earth’s water cycles through organisms: • Plant roots take up water which is used in photosynthesis and also makes up part of the plant • Animals drink water which becomes part of their bodies • Water transpires from plant leaves, returning to the atmosphere • Animals return water to the abiotic environment through sweat and urine

35. BALANCE OF NUTRIENTS What happens if: There is a short supply of a nutrient in an ecosystem? The size of populations in that ecosystem will be limited. A nutrient in short supply is called a LIMITING FACTOR There is too much of a nutrient in an ecosystem? Populations grow so large they fill the ecosystem, then die and decompose, causing problems