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Ch. 50 Learning Objectives

Ch. 50 Learning Objectives. Understand the scale of ecology (populations – biosphere), Understand the importance of incoming solar radiation and the tilt of the Earth in determining the distribution of major terrestrial biomes Understand the basic characteristics of aquatic biomes.

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Ch. 50 Learning Objectives

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  1. Ch. 50 Learning Objectives • Understand the scale of ecology (populations – biosphere), • Understand the importance of incoming solar radiation and the tilt of the Earth in determining the distribution of major terrestrial biomes • Understand the basic characteristics of aquatic biomes.

  2. Ch. 51: Population Ecology • Understand the factors influencing… • the distribution of individuals in populations • the range of a population • The size of a population • Understand survivorship curves and the life history patterns reflected therein • Understand r- vs. k- selection • Understand the components of the Logistic Growth curve, and explain the relationship between individuals and their immediate environment that drives the logistic growth model.

  3. Population Ecology The Big Concepts. But first, what is Population Ecology? The study of populations in relation to the environment, including environmental influences on density, distribution, age structure, and variations in population size.

  4. Density and Dispersion

  5. Can we view Population Ecology as“Limits to Geographic Distribution”?

  6. What else governs a population’s size? • According to C. Darwin: for any species, population sizes will increase exponetially if all individuals that are born reproduce successfully. • Call this biotic potential • The intrisitc rate of increase is called “r” • Several factors influence r: • age of reproduction, number of offspring, viability of offspring, generation time, frequency of mating, number of matings/individual • r is always met by K (the carrying capacity) aka Environmental Resistance

  7. Population Growth: Exponential Model r= intrinsic rate of growth (r = b - m) aka: rmax > 0

  8. Population Growth: Logistic Model K - N K Narrative account?

  9. Population Growth in Real World: Populations oscillate around K

  10. Using Life Tables to study Population DynamicsAdapted from the Life Insurance Business

  11. Life Tables help generate Survivorship Curves

  12. Life Histories! Traits that affect an organism’s “schedule” of reproduction and survival. • Different strategies… • Individual strategies are selected for, and those strategies are reflected in the population • In general, individuals in populations will exhibit: • Semelparity: Live fast, (and you only live once!) • Iteroparity: repeated reproductive events throughout the course of a lifetime

  13. r-selection vs. K-selection • r-selection: density independent selection: • observed in organisms that maximize reproductive success in uncrowded environments • maximize rate of increase: occupy a habitat • K-selection: density-dependent selection. • Sensitive to population increases, live near K, maximize competition and resource utilization near K. • Larger, territorial organisms • How does this relate to Survivorship curves? • How does this relate to reproductive strategy?

  14. Limits on Population Growth Density-dependent factors: negative feedback on large populations 1. Intra_______ c_______ for resources: 2. PP: 3. DWT: What about density independent factors? How are the two related?

  15. Human Population Growth 101 • You guys will graph it. • Has humanity been at in an exponential growth curve during our recent history? • Are we in one now, are are we slowing down? • The current intrinsic rate of growth r is… • But the world is “upside down”… Developed Countries(MDC) Developing Countries (LDC) r TFR IMR LE

  16. Age Structure Pyramids:pictures say 1000s of words

  17. Ch 53: Community Ecology • Understand basic of community ecology concepts • focus on species interactions as a win/win or win/lose situation • concepts like niche, generalist and specialist • Understand the more dynamic, and difficult, aspects of community ecology including Disturbance, Succession and Island Biogeography. • Understand the trophic aspects of community ecology: food webs, food chains and trophic structure.

  18. Community Ecology:The Big Concepts • Community Interactions • Competition, Predation, Parasitism, etc. • Trophic Interactions • Food Webs, Trophic Levels, Top Down v. Bottom Up (Lakes) • Functional groups • Disturbance and Succession! • Biodiversity, Species Richness and Island Biogeography • Species Richness v. Relative Abundance • Equatorial-Polar Decline in Biodiversity • Comparison of Rates of Immigration and Extinction • Your job…Find examples of, and write one page paragraphs about each of the following: • Keystone Species/Ecosystem Engineers • Invasive Species • A documented decline in biodiversity, the root cause of that decline, and the potential ramifications of that decline.

  19. Ecosystem Ecology • Primarily focused on Energy flow through, and material cycling within, ecosystems (a “bottom-up” approach) • Broader in scope: organizes trophic levels into functional groups • Comparison of primary productivity across ecosystems • Analysis of energy flow through different trophic levels

  20. What is a community, How are they assembled? • Community is… • How are communities assembled? • Integrative • Rivet Theory • “Brick Wall” • Individualistic • Redundancy Model • Niches are filled by indpendent spp. • So, what IS an ecological niche?

  21. An “organismal approach” to Community Ecology: Interspecific Interactions

  22. Interspecific Competition Fundamental Niche vs. Realized Niche What is going on here?

  23. Reductions in Interspecific Competition • Habitat Partitioning • Anolis Lizards in Dominican Republic • Character Displacement • Galapogos Finches • Geospiza

  24. Predation: Lynx and Snowshoe Hare

  25. Predator Avoidance • Plants • Physical Adaptations… -- Chemical Adaptations… • Animals • Cryptic Coloration (camo) • Aposematic Coloration (red) • Batesian Mimicry, • (read to the students) • Coral vs. King Snakes (snapshot) • Muellerian Mimicry

  26. Feeding relationships, a Common Theme in Community Ecology • Food Webs • Trophic Structure • Trophic Links • Keystone Predators • “Top-Down” vs. “Bottom Up” Community Structure • The River Continuum

  27. Simple Food Web

  28. A more complex Food Web • Webs are comprised of… • Food Chains • Food Chains are comprised of Trophic Links

  29. Trophic Structure: Links & Levels • Producers • Primary Consumers • Secondary Consumers • Tertiary Consumers Energetic Hypothesis Dynamic Stability Hypothesis

  30. Community Structure Established by Trophic Interactions • KEYSTONE SPECIES/ KEYSTONE PREDATORS • Robert Paine (U. of Washington) • Pisaster vs. Mytilus

  31. “Bottom Up” vs. “Top Down” Trophic Stucture is a bit more comprehensive than the Keystone Predator Concept

  32. “Bottom Up” vs. “Top Down”: Where (some of) the work was performed

  33. “Top Down” Model can Result in a “Trophic Cascade” Top Predator Planktivorous Fish Zooplankton Phytoplankton ----- Macrophytes Top Predator Planktivorous Fish Zooplankton Phytoplankton ----- Macrophytes

  34. Opposing Views, but both have real world applications

  35. Stream Communities: “The River Continuum”A “Bottom-Up” Model A B A B C D C D

  36. Disturbance: The only thing constant is changeDisturbance is…

  37. More Ecological Disturbances • What is a disturbance? • Bottom Line: Communities are in a state of Non-equilibrium • These disturbances allow ecologists to study SUCCESSION: What about the intermediate disturbance hypothesis?

  38. Succession • Primary Succession • Secondary Succession

  39. 2 Sides to Biodiversity • Both Communities Have the same: Species Richness • But Community A is more heterogenous; Relative Abundance is more equitable • Which community has greater Biodiversity?

  40. Species Richness • What can we say about these data? • Why? 1) 2)

  41. More species richness curves Species Richness correlates with evapotranspiration. What’s the deal here? How does this relate to climate? How might this relate to climate change?

  42. Island Biogeography • “Islands” make good case studies in species richness • Remember this is a dynamic equilibrium • Large v. Small: • Near v. Far:

  43. Ch 54: Ecosystem Ecology • Students should be able to recognize the different trophic levels in this model and see that Energy flows through ecosystems and materials are recycled within ecosystems. • Students should also understand these three nuances of ecosystems: • the “rule of 10” Generally, only 10% of the biomass at one trophic level is converted to biomass at the next trophic level. The other 90% is lost as heat. • the synergy between decomposers and remineralizers maintains ecosystem function. • The energy for an ecosystem is ultimately derived from the sun, but the remineralizers return the raw materials back to primary producers so they can sustain the trophic pyramids. • understand community productivity and community respiration and the difference between Gross Primary Productivity • Students should recognize the components of a biogeochemical cycle and be able to describe (in general) how the carbon cycle, nitrogen cycle, and hydrologic cycle. They should also be able to briefly describe how humans have disrupted or changed a particular cycle.

  44. Ecosystem Ecology • Ecosystems as machines • Much of this should be review: • Trophic Levels: Detritus links it all • Microorganisms remineralize the detritus • Gross PP v. Net PP • Tropic Pyramids (Charles Elton) • Biogeochemical Cycles • Human Impacts? If we have time

  45. An Ideal Ecosystem Model:Nutrients:Energy:

  46. What about a “narrative model” Animals and plants in associations with each other and with the physical factors of their surroundings, as a fundamental ecological system. An ecosystem. Biological and physical parts of nature are interdependent. Plants and animals depend on their physical surroundings, and they contribute to the maintenance of the physical world. --A.G. Tansley (c. 1920)

  47. Chapter 54, Ecosystems: The Big Ideas Eltonian Pyramids (Producers & Consumers) Biogeochemical Cycles: Conservation of Energy)( Detritivores and Decomposers “10% rule”: Laws of thermodynamics

  48. Ecological Pyramids

  49. Energy Flow Through Ecosystems:Eltonian Pyramids Rule of Thumb:

  50. Net Primary Productivity NPP = GPP - R (gC/m2/year)

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