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ENVIRONMENTAL SCIENCE

13e. ENVIRONMENTAL SCIENCE. CHAPTER 5: Biodiversity, Species Interactions, and Population Control. Fig. 5-1, p. 79. Fig. 5-1, p. 79. Homework watch video. http://www.youtube.com/watch?v=Wcy-i_IJH9Y. Core Case Study: Endangered Southern Sea Otter (1).

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ENVIRONMENTAL SCIENCE

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  1. 13e ENVIRONMENTALSCIENCE CHAPTER 5:Biodiversity, Species Interactions, and Population Control

  2. Fig. 5-1, p. 79

  3. Fig. 5-1, p. 79

  4. Homeworkwatch video • http://www.youtube.com/watch?v=Wcy-i_IJH9Y

  5. Core Case Study: Endangered Southern Sea Otter (1) • Santa Cruz to Santa Barbara shallow coast • Live in kelp forests • Eat shellfish • ~16,000 around 1900 • Hunted for fur and because considered competition for abalone and shellfish

  6. Core Case Study: Endangered Southern Sea Otter (2) • 1938-2008: increase from 50 to ~2760 • 1977: declared an endangered species Keystone species: plays a role affecting many other organisms in ecosystem specificallysea otters eat sea urchins that would otherwise destroy kelp forests Kelp forests provide essential habitat for entire ecosystem

  7. Science Focus: Sea Urchins Threaten Kelp Forests (1) • Kelp forests • Can grow two feet per day • Require cool water • Host many species – high biodiversity • Fight beach erosion • Algin

  8. Science Focus: Sea Urchins Threaten Kelp Forests (2) • Kelp forests threatened by • Sea urchins • Pollution • Rising ocean temperatures • Southern sea otters eat urchins • Keystone species

  9. Fig. 5-A, p. 82

  10. 5-1 How Do Species Interact? • Concept 5-1 Five types of species interactions affect the resource use and population sizes of the species in an ecosystem.

  11. Species Interact in 5 Major Ways • Interspecific competition • Predation • Parasitism • Mutualism • Commensalism

  12. In Class Assignment:What are the 5 major ways species interact?Define each • Interspecific competition • Predation • Parasitism • Mutualism • Commensalism

  13. Interspecific Competition • No two species can share vital limited resources for long • Resolved by: • Migration • Shift in feeding habits or behavior • Population drop • Extinction • Intense competition leads to resource partitioning

  14. Blackburnian Warbler Black-throated Green Warbler Cape May Warbler Bay-breasted Warbler Yellow-rumped Warbler Resource Partitioning of 5 species of insect eating warblers Stepped Art Fig. 5-2, p. 81

  15. Predation (1) • Predator strategies • Herbivores can move to plants • Carnivores • Pursuit • Ambush • Camouflage • Chemical warfare

  16. Predation (2) • Prey strategies • Evasion • Alertness – highly developed senses • Protection – shells, bark, spines, thorns • Camouflage

  17. Predation (3) • Prey strategies, continued • Mimicry • Chemical warfare • Warning coloration • Behavioral strategies – puffing up

  18. Ways in which prey species avoid their predators Camouflage (a) Span worm (b) Wandering leaf insect Fig. 5-3, p. 83

  19. Chemical Warfare Warning coloration (c) Bombardier beetle (d) Foul-tasting monarch butterfly Fig. 5-3, p. 83

  20. Chemical warfare; warning coloration Mimicry (e) Poison dart frog (f) Viceroy butterfly mimics monarch butterfly Fig. 5-3, p. 83

  21. Deceptive looks Deceptive behavior (h) When touched, snake caterpillar changes shape to look like head of snake. (g) Hind wings of Io moth resemble eyes of a much larger animal. Fig. 5-3, p. 83

  22. Coevolution • Predator and prey • Intense natural selection pressure on each other • Each can evolve to counter the advantageous traits the other has developed • Bats and moths

  23. Fig. 5-4, p. 83

  24. Parasitism • Live in or on the host • Parasite benefits, host harmed • Parasites promote biodiversity

  25. Fig. 5-5, p. 84

  26. Fig. 5-5, p. 84

  27. Relationships often more complicated than they first seem • Mistletoe a parasite and a keystone species? • http://news.nationalgeographic.com/news/2007/12/071224-mistletoe-research.html

  28. Mutualism • Both species benefit • Nutrition and protection • Gut inhabitant mutualism

  29. Fig. 5-6, p. 85

  30. Fig. 5-6, p. 85

  31. Commensalism • Benefits one species with little impact on other

  32. Fig. 5-7, p. 85

  33. 5-2 What Limits the Growth of Populations? • Concept 5-2 No population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources.

  34. Limits to Population Growth (1) • Biotic potential is idealized capacity for growth • Ex. With no controls on pop growth a species of bacteria that can reproduce every 20 minutes would generate enough offspring to form a layer 1 foot deep over the entire earth’s surface in just 36 hrs • Intrinsic rate of increase (r):rate at which a population could grow if it had unlimited resources • Nature limits population growth with resource limits and competition • Environmental resistance: the combination of all factors that act to limit the growth of a population • Carrying capacity: the max pop of a given species that a particular habitat can support indefinitely

  35. Limits to Population Growth (1) • Exponential growth- starts slowly but then accelerates as the pop increases because the base size of the pop is increasing (J shaped curve) • Logistic growth- growth rate decreases as the pop becomes larger and faces environmental resistance ; over time , the pop size stabilizes at or near the carrying capacity of its environment which results in a sigmoid (S shaped) population growth curve

  36. Overshoot and Dieback • Population not transition always smooth from exponential to logistic growth • Overshoot carrying capacity of environment • Caused by reproductive time lag (the time needed for the birth rate to fall and the death rate to rise in response to resource overconsumption) • Dieback (Population Crash), unless excess individuals switch to new resource

  37. Different Reproductive Patterns • r-Selected species • Many, usually small offspring, give them little parental care or protection • These species overcome massive losses of offspring by producing so many that a few will likely survive to begin to reproduce again • K-selected species • Slowly reproducing, reproduce later in life, ex. Mammals offspring develop inside mother’s body’s where they are safe, parents devote much time to care of young • Most species’ reproductive cycles between two extremes

  38. 5-3 How Do Communities and Ecosystems Respond to Changing Environmental Conditions? • Concept 5-3 The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession.

  39. Ecological Succession: gradual change in species composition in a given area • Primary succession-involves the gradual establishment of biotic communities in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem • Secondary succession- contains soil or sediment • Disturbances create new conditions

  40. Succession’s Unpredictable Path • Successional path not always predictable toward climax community • Communities are ever-changing mosaics of different stages of succession • Continual change, not permanent equilibrium

  41. Inertia, persistence (the ability of a living system such as a forest or grassland to survive moderate disturbances) • Resilience the ability of a living system to be restored thru secondary succession after a more severe disturbance • Ecological tipping point • Tropical rain forests vs less diverse tropical grasslands

  42. Succession at Mt. St. Helens • http://news.nationalgeographic.com/news/2005/05/0513_050513_mountsthelens.html • http://ngm.nationalgeographic.com/2010/05/mount-st-helens/funk-text

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