Ecological Principles

1. Lecture 13 Ecological Principles

2. Ecology Ecology = the study of the interaction of organisms with their environments.

3. Ecology It involves understanding biotic and abiotic factors influencing the distribution and abundance of living things.

4. Biotic & Abiotic Factors • Biotic Factors • Competitors • Disease • Predators • Food availability • Habitat availability • Symbiotic relationships • Abiotic Factors • pH • Temperature • Weather conditions • Water availability • Chemical composition of environment • nitrates, phosphates, ammonia, O2, pollution

5. Ecology The word "ecology" coined from Greek word "oikos", which means "house" or "place to live”.

6. The Scope of Ecology • population growth • competition between species • symbiotic relationships • trophic (=feeding) relationships • origin of biological diversity • interaction with the physical environment

7. The Biosphere • The entire proportion of the earth that is inhabited by life. • Includes communities and ecosystems.

8. Forest Desert Tundra Savanna Biome A major type of ecological community, determined largely by climate and dominate vegetation.

9. Aquatic Biomes

10. Some Important Terms Population- A group of individuals of a single species that live in a particular area and interact with one another.

11. Some Important Terms Community-An association of populations of different species living in the same area.

12. Some Important Terms Ecosystem- comprised of 1 or more communities and the abiotic environment within an area.

13. Physiological Limits Environmental Gradient

14. Physiological Limits Range of Tolerance

15. Physiological Limits Zones of Intolerance

16. Physiological Limits Optimum Range

17. Physiological Limits Zones of Physiological Stress

18. Birth Emigration Death Immigration Immigration Births Population (N) Deaths Figure 1. The size of a population is determined by a balance between births, immigration, deaths and emigration Emigration Population Parameters that effectsizeordensityof a population:

19. Generation Population Size 1 2 3 4 5 6 7 8 9 10 1 2 4 8 16 32 64 128 256 512 Population Growth

20. 600 Exponential Population Growth 500 400 Population Size 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Number of Generations Unlimited resources

21. Population Growth exponential k • k= carrying capacity • kis affected by: • food production • resource supply • the env.’s ability to assimilate pollution sigmoidal k

22. Density Dependent vs Density Independent Factors Influencing Population Size

23. Density Dependent Factors Increasing population density reduces resources and limits pop growth • limiting resources (e.g., food & shelter) • production of toxic wastes • infectious diseases • predation • stress • emigration

24. Density Independent Factors • severe storms and flooding • sudden unpredictable severe cold • spells • earthquakes and volcanoes • catastrophic meteorite impacts

25. Competition Among Species

26. Ecological Niche Concept Ecological niche = the "role" a species "plays" in the ecosystem. An organisms use of biotic and abiotic resources in its environment

27. Ecological Niche Concept Contrast the ecological niche with the "habitat" which is the physical environment in which the organism lives.

28. Ecological Niche Concept The ecological niche of a species, therefore includes: species’ habitat abiotic & biotic interactions

29. Competative Exclusion Principle No two similar species occupy the same niche at the same time.

30. Possible Outcomes of Competition Extinction of one species

31. Extinction of One Species extinction Constant food supply G. F. Gause (1934) tested competitive exclusion principle

32. Possible Outcomes of Competition Resource partitioning: splitting the niche

33. Resource Partitioning Insect-eating warblers Sympatric species consume slightly different resources or use resources in slightly different ways

34. Possible Outcomes of Competition Character displacement: two similar species evolve in such a way as to become different from each other by accentuating their initial minor differences

35. Character Displacement Allopatric vs Sympatric populations

36. Character Displacement Allopatric populations: Similar beak morphologies and eat similar sized seeds

37. Character Displacement Avoids competition

38. Predator-Prey Relationships

39. Outcomes of Predator-Prey Interactions • Offset oscillations in the population sizes of the predator and prey • Coevolution of predator and prey

40. Oscillations in Predator-Prey Interactions

41. Biogeochemical Cycles

42. Respiration C6H12O6 + 6O2  6CO2 + 6H2O + energy Animal cell

43. Photosynthesis 6CO2 + 6H2O + energy  C6H12O6 + 6O2

44. CARBON CYCLE Carbon Cycle

45. Humans affect the carbon cycle Burning fossil fuels moves carbon from the ground to the air. Cutting forests and burning fields moves carbon from organisms to the air. Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years. The driving force behind climate change

46. The phosphorus cycle

47. Humans affect the phosphorus cycle Mining rocks for fertilizer moves phosphorus from the soil to water systems. Wastewater discharge also releases phosphorus, which boosts algal growth and causes eutrophication. May be present in detergents Consumers should purchase phosphate-free detergents.

48. Nitrogen Cycle

49. Humans affect the nitrogen cycle Excess nitrogen leads to hypoxia in coastal areas. Synthetic fertilizers doubled the rate of Earth’s nitrogen fixation. Burning forests and fossil fuels leads to acid precipitation. Wetland destruction and increased planting of legumes has increased nitrogen-rich compounds on land and in water. Increased emissions of nitrogen-containing greenhouse gases Calcium and potassium in soil are washed out by fertilizers. Reduced biodiversity of plants adapted to low-nitrogen soils. Changed estuaries and coastal ecosystems and fisheries

50. Human inputs of nitrogen into the environment Fully half of nitrogen entering the environment is of human origin.