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Southern Sea Otters: Back from the Brink of Extinction?

Explore the recovery of Southern Sea Otters, their importance as a keystone species, and the various ways species interact in an ecosystem. Learn about competition, predation, parasitism, mutualism, and commensalism, and how these interactions shape population control and biodiversity.

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Southern Sea Otters: Back from the Brink of Extinction?

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  1. Chapter 5 Biodiversity, Species Interactions, and Population Control

  2. Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction? • Habitat • Hunted: early 1900s • Partial recovery • Why care about sea otters? • Ethics • Tourism dollars • Keystone species

  3. Southern Sea Otter Fig. 5-1a, p. 104

  4. 5-1 How Do Species Interact? • Concept 5-1 Five types of species interactions—competition, predation, parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an ecosystem.

  5. Species Interact in Five Major Ways • Interspecific Competition • Predation • Parasitism • Mutualism • Commensalism

  6. Most Species Compete with One Another for Certain Resources • For limited resources • Ecological niche for exploiting resources • Some niches overlap

  7. Some Species Evolve Ways to Share Resources • Resource partitioning • Using only parts of resource • Using at different times • Using in different ways

  8. Resource Partitioning Among Warblers Fig. 5-2, p. 106

  9. Specialist Species of Honeycreepers Fig. 5-3, p. 107

  10. Most Consumer Species Feed on Live Organisms of Other Species (1) • Predators may capture prey by • Walking • Swimming • Flying • Pursuit and ambush • Camouflage • Chemical warfare

  11. Predator-Prey Relationships Fig. 5-4, p. 107

  12. Most Consumer Species Feed on Live Organisms of Other Species (2) • Prey may avoid capture by • Run, swim, fly • Protection: shells, bark, thorns • Camouflage • Chemical warfare • Warning coloration • Mimicry • Deceptive looks • Deceptive behavior

  13. Some Ways Prey Species Avoid Their Predators Fig. 5-5, p. 109

  14. (a) Span worm Fig. 5-5a, p. 109

  15. (b) Wandering leaf insect Fig. 5-5b, p. 109

  16. (c) Bombardier beetle Fig. 5-5c, p. 109

  17. (d) Foul-tasting monarch butterfly Fig. 5-5d, p. 109

  18. (e) Poison dart frog Fig. 5-5e, p. 109

  19. (f) Viceroy butterfly mimics monarch butterfly Fig. 5-5f, p. 109

  20. (g) Hind wings of Io moth resemble eyes of a much larger animal. Fig. 5-5g, p. 109

  21. (h) When touched, snake caterpillar changes shape to look like head of snake. Fig. 5-5h, p. 109

  22. Science Focus: Threats to Kelp Forests • Kelp forests: biologically diverse marine habitat • Major threats to kelp forests • Sea urchins • Pollution from water run-off • Global warming

  23. Purple Sea Urchin Fig. 5-A, p. 108

  24. Predator and Prey Interactions Can Drive Each Other’s Evolution • Intense natural selection pressures between predator and prey populations • Coevolution • Interact over a long period of time • Bats and moths: echolocation of bats and sensitive hearing of moths

  25. Coevolution: A Langohrfledermaus Bat Hunting a Moth Fig. 5-6, p. 110

  26. Some Species Feed off Other Species by Living on or in Them • Parasitism • Parasite is usually much smaller than the host • Parasite rarely kills the host • Parasite-host interaction may lead to coevolution

  27. Parasitism: Trout with Blood-Sucking Sea Lamprey Fig. 5-7, p. 110

  28. In Some Interactions, Both Species Benefit • Mutualism • Nutrition and protection relationship • Gut inhabitant mutualism • Not cooperation: it’s mutual exploitation

  29. Mutualism: Hummingbird and Flower Fig. 5-8, p. 110

  30. Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish Fig. 5-9, p. 111

  31. In Some Interactions, One Species Benefits and the Other Is Not Harmed • Commensalism • Epiphytes • Birds nesting in trees

  32. Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree Fig. 5-10, p. 111

  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. Most Populations Live Together in Clumps or Patches (1) • Population: group of interbreeding individuals of the same species • Population distribution • Clumping • Uniform dispersion • Random dispersion

  35. Most Populations Live Together in Clumps or Patches (2) • Why clumping? • Species tend to cluster where resources are available • Groups have a better chance of finding clumped resources • Protects some animals from predators • Packs allow some to get prey

  36. Population of Snow Geese Fig. 5-11, p. 112

  37. Generalized Dispersion Patterns Fig. 5-12, p. 112

  38. Populations Can Grow, Shrink, or Remain Stable (1) • Population size governed by • Births • Deaths • Immigration • Emigration • Population change = (births + immigration) – (deaths + emigration)

  39. Populations Can Grow, Shrink, or Remain Stable (2) • Age structure • Pre-reproductive age • Reproductive age • Post-reproductive age

  40. Some Factors Can Limit Population Size • Range of tolerance • Variations in physical and chemical environment • Limiting factor principle • Too much or too little of any physical or chemical factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance • Precipitation • Nutrients • Sunlight, etc

  41. Trout Tolerance of Temperature Fig. 5-13, p. 113

  42. No Population Can Grow Indefinitely: J-Curves and S-Curves (1) • Size of populations controlled by limiting factors: • Light • Water • Space • Nutrients • Exposure to too many competitors, predators or infectious diseases

  43. No Population Can Grow Indefinitely: J-Curves and S-Curves (2) • Environmental resistance • All factors that act to limit the growth of a population • Carrying capacity (K) • Maximum population a given habitat can sustain

  44. No Population Can Grow Indefinitely: J-Curves and S-Curves (3) • Exponential growth • Starts slowly, then accelerates to carrying capacity when meets environmental resistance • Logistic growth • Decreased population growth rate as population size reaches carrying capacity

  45. Logistic Growth of Sheep in Tasmania Fig. 5-15, p. 115

  46. Science Focus: Why Do California’s Sea Otters Face an Uncertain Future? • Low biotic potential • Prey for orcas • Cat parasites • Thorny-headed worms • Toxic algae blooms • PCBs and other toxins • Oil spills

  47. Population Size of Southern Sea Otters Off the Coast of So. California (U.S.) Fig. 5-B, p. 114

  48. Case Study: Exploding White-Tailed Deer Population in the U.S. • 1900: deer habitat destruction and uncontrolled hunting • 1920s–1930s: laws to protect the deer • Current population explosion for deer • Spread Lyme disease • Deer-vehicle accidents • Eating garden plants and shrubs • Ways to control the deer population

  49. Mature Male White-Tailed Deer Fig. 5-16, p. 115

  50. When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash • A population exceeds the area’s carrying capacity • Reproductive time lag may lead to overshoot • Population crash • Damage may reduce area’s carrying capacity

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