How organisms interact with their environment

1. ECOLOGY How organisms interact with their environment

2. What is Ecology? • Ecology:the study of relationships between organisms and the environment. • Ecologists will study populations, rates of photosynthesis, nutrient cycles, soil chemistry, etc., to try to piece together how ecosystems work. • Ecosystem:includes all the organisms that live in an area and the physical environment with which those organisms interact.

3. Ecologists typically concentrate on one level of ecology • Ecology is such a complex field, that it is necessary for ecologists to narrow their studies to a particular level. The 4 main levels of ecology are: • Ecosystem: studies focus on energy flow and nutrient cycling, and include investigating the living and nonliving components. • Organismal: studies focus on ways in which an individual organism meets the challenges of its environment. • Population: studies mainly focus on factors affecting population size and distribution. • Community: studies focus on the interactions of living organisms of many species in a particular area.

4. Energy in Ecosystems

5. All organisms require energy to live • Some organisms make (produce) their own energy • Producers/autotrophs • Usually plants that use energy from the sun to make their own food • Can also be chemosynthetic bacteria that use inorganic molecules to make their own carbohydrates (food)

6. All organisms require energy continued… • Many organisms get their energy from other organisms • Consumers/Heterotrophs (primary, secondary, tertiary, etc.) • Herbivores– get their energy from eating plants • Carnivores– get their energy from eating other animals • Omnivores– eat plants and animals • Detritivores– eat only “dead” organisms • Decomposers– bacteria and fungi that break down large molecules found in waste into smaller molecules

7. Autotroph/Heterotrophs

8. Energy Flow: The food chain • All energy in an ecosystem begins with the producers that make their own food/energy • A food chain shows that the energy then flows from the producers to the primary consumer and beyond

9. Food Chains

10. Energy Flow: The Food Web • Food chains in an ecosystem often overlap as a result of an organism being eaten by more than one type of consumer • The diagram that shows how energy flows between all of the organisms in an ecosystem is known as a food web (a series of overlapping food chains)

11. A Food Web

12. A Food Web

13. A Food Web

16. Another way to look at energy flow: the trophic level pyramid • Trophic level pyramids also show how energy flows in an ecosystem • Producers form the base of the pyramid because they are the base of the food web • Primary consumers are the next level, followed by secondary consumers, etc.

17. Energy Pyramid or Trophic Levels Tertiary Consumer Secondary Consumer Primary consumer Producers

18. Trophic Level Pyramid

19. Why is the bottom of the pyramid so much bigger than the top? • The size of each level represents the amount of energy that is available at that level • Only about 10% of the available energy makes its from one level to the next level (not all of an organism is eaten, some energy is lost as heat during metabolism, etc. • Since producers create their own food/energy from the sun or molecules, they have 100% energy • Using the 10% assumption, the primary producers would only have 10% of the producers’ original energy • Secondary consumers would have 1%, tertiary consumers 0.10%, etc.

20. Pyramid shape continued… • The result is that many producers are required at the bottom of a pyramid to support only a few higher-level consumers at the very top • This low level of energy transfer keeps food chains fairly short

21. Energy Flow

23. Flow of Energy

24. More Pyramids

25. Why aren’t detritivores part of the trophic level pyramid? • Detritivores rarely pass energy onto the next level in the pyramid. Rather, they obtain some of the energy that is “lost” in each energy transfer by consuming the energy in the “leftovers” that might not otherwise be eaten. • Since they don’t pass energy on to higher levels of the pyramid, they are not shown in the pyramid

26. Why do some ecosystems have more extensive food webs and species richness than others? • The species richness in an ecosystem is entirely dependent upon the producers • If conditions (temperature, sunlight, water, etc.) are good there will be many producers and high primary productivity (increase in mass of producers) • More producers = more energy available for consumers = more consumers=high species richness • Tropical rainforests and estuaries have high productivity and species richness, while deserts and temperate grasslands have much lower values

27. Important Cycles • In addition to energy, more than 20 different substances must be present in an ecosystem for life processes to occur. • The main elements required for life are CHON. • Unlike energy, these substances are constantly recycled within an ecosystem.

28. Cycle Overview

29. Carbon Cycle • Carbon makes up about .03% of the atmosphere. • The increase in the burning of fossils fuels is currently adding CO2 to the atmosphere faster than it is being removed. • This increase has started the debate over Global Warming, excess CO2 seems to act like a blanket, preventing heat from escaping into the atmoshere.

30. Carbon Cycle

31. Carbon Cycle

32. Carbon Cycle

33. Nitrogen Cycle • Nitrogen makes up about 79% of the atmosphere. • Plants can not use this nitrogen to make their proteins. This is a problem. • Bacteria provide the solution. • Nitrogen Fixing bacteria convert the nitrogen from the air into nitrates that can be used by the plants. • Nitrates are compounds that contain nitrogen and oxygen. • Animals eat the plants, thus passing the nitrogen along.

34. Nitrogen Cycle • Decomposing organisms: Bacteria cause the protein (containing nitrogen) in the decaying animal to combine with hydrogen. This forms ammonia. • Metabolic wastes are also changed into ammonia by bacteria. • The process of making ammonia is called ammonification.

35. Nitrogen Cycle • Different bacteria then change the ammonia to nitrates, which can be absorbed by the roots of plants. • This process is called nitrification. • It would not be a cycle if nitrogen were not returned to the air. Guess who does this? • Why yes, bacteria do! The process that sends nitrogen back to the air is called denitrification.

36. Nitrogen Cycle

37. Water Cycle • You are already familiar with the water cycle. • Words you should know: precipitation, transpiration, evaporation, run off.

38. Water Cycle

39. Water Cycle

40. Organisms and their interactions with their environment

41. Abiotic and Biotic components influence populations of species • Abiotic factors are nonliving factors that can affect organisms. Examples include light, temperature, pH, and salinity. • Biotic factors are living factors that can affect organisms. Examples include predation, competition, and food resources. • Abiotic and biotic factors play a role in defining an organism’s niche.

42. Habitat vs. Niche • An organism’s living conditions consist of both its habitat and its niche. How do they differ? • Habitat: the area where an organism lives • Niche: the role that an organism plays in its habitat; its “way of life” • describes how a species uses the biotic and abiotic resources for growth, survival and reproduction

43. Two Types of Niches • Fundamental niche: range of conditions and resources that a species can tolerate and use • This can be very large for some species • Realized niche: range of resources and conditions actually used by a species • Much smaller than the fundamental niche

44. Niche continued • The realized niche helps to explain why so many species can coexist in the same habitat • Ex: warbler foraging zones • What happens when two species try to occupy the same niche? • Two species can occupy the same niche for a short time, but one species will eventually out-compete the other

45. Dealing with change • The size of an organism’s niche can greatly affect how threatened an organism is by changes to its niche • Generalists can tolerate some change to their niche because they have a large range of conditions they can tolerate and resources they can use • Ex: humans, possums (live in suburban areas and can survive on garbage) • Specialists are greatly affected by change due to having a very small niche; they may use a very limited resource • Ex: koalas (live in trees and eat eucalyptus), pandas (eat bamboo)

46. Dealing with change cont. • Some organisms can acclimate (adjust) to changed conditions • Happens in a short period of time • Adjusting tolerance to abiotic factors • Ex: humans at high elevations will acclimate to lower oxygen levels by producing more red blood cells to carry oxygen

47. Dealing with change cont. • Organisms may acclimate to changing conditions in two ways: • Conformers will actually change as their external (outside) conditions change • Ex: lizard body temperature matches whatever the external temperature is • Regulators use energy to control some of their internal conditions even when external conditions change • Ex: human body temperature remains relatively stable even as temperatures range from cold to hot

48. Dealing with change cont. • A species may also adapt to changes in its habitat • Takes a long time • Involves genetic changes in the whole species (not one organism) over a many generations • Also known as evolution • Ex: Finch species in the Galapagos islands have evolved beak sizes and shapes that are ideal for the type of food they eat

49. Populations

50. Population Dynamics • What types of things affect the size of a population? • Immigration: New members entering a population from outside the area • Emigration: Members of an existing population leaving the area • Birth Rate • Death Rate