Species Interactions: Competition, Predation, Parasitism, Mutualism, and Commensalism

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 – occurs when members of 2 or more species interact to gain access to the same limited resources • Predation – when one species eats another • Parasitism - when one organism feeds on another by living on them • Mutualism – an interaction benefits both species • Commensalism – One species benefits the other is unaffected. pg 105

6. Most Species Compete with One Another for Certain Resources • For limited resources like food light and space • Ecological niche for exploiting resources • Some niches overlap – the greater the overlap the more competition • If one species is more successful the others, the others have to move, adapt by shifting feeding habits or behavior, suffer population decline, become extinct

7. Some Species Evolve Ways to Share Resources • Resource partitioning • Using only parts of resource – different parts of the tree or shore. • Using at different times • Using in different ways – eating different species of insects.

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

9. Specialist Species of Honeycreepers This is called adaptive radiation. Fig. 5-3, p. 107

10. Most Consumer Species Feed on Live Organisms of Other Species (1) • Predatorsmay capture prey by • Walking • Swimming • Flying • Pursuit and ambush • Camouflage • Chemical warfare Types Herbivores Omnivores Insectivores Carnivores

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 – with highly developed senses. • Protection: shells, bark, thorns • Camouflage • Chemical warfare • Warning coloration – often black and yellow stripes • Mimicry • Deceptive looks • Deceptive behavior If it is small and strikingly beautiful it is probably poisonous. If it is strikingly beautiful and easy to catch it is probably deadly. E.O. Wilson

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 – warming oceans

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

24. Predator and Prey Interactions Can and Do 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 – micro-organisms in cows and termites stomachs. • 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 – plants that grow on other plants (air plants) • 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 - 3 types • 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. (a) Clumped (elephants) Fig. 5-12a, p. 112

39. (b) Uniform (creosote bush) Fig. 5-12b, p. 112

40. (c) Random (dandelions) Fig. 5-12c, p. 112

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

42. Populations Can Grow, Shrink, or Remain Stable (2) • Age structure – distribution of individuals of various age groups • Pre-reproductive age • Reproductive age • Post-reproductive age

43. Some Factors Can Limit Population Size • Range of tolerance • Variations in physical and chemical environment that the organism can live with. • 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

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

45. 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

46. 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

47. 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

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

49. 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

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