Chapter 5 Biodiversity, Species Interactions, and Population Control

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

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

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

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

5. Resource Partitioning Among Warblers Figure 5.2:Sharing the wealth: This diagram illustrates resource partitioning among five species of insect-eating warblers in the spruce forests of the U.S. state of Maine. Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion (yellow highlighted areas) of the spruce trees, and by consuming somewhat different insect species. (After R. H. MacArthur, “Population Ecology of Some Warblers in Northeastern Coniferous Forests,”Ecology 36 (1958): 533–536.) Fig. 5-2, p. 106

6. Specialist Species of Honeycreepers Figure 5.3:Specialist species of honeycreepers: Through natural selection, different species of honeycreepers developed specialized ecological niches that reduced competition between these species. Each species has evolved a specialized beak to take advantage of certain types of food resources. Fig. 5-3, p. 107

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

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

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

10. chemical warfare (c) Bombardier beetle Fig. 5-5c, p. 109

11. chemical warfare (d) Foul-tasting monarch butterfly Fig. 5-5d, p. 109

12. warning coloration (e) Poison dart frog Fig. 5-5e, p. 109

13. warning coloration (f) Viceroy butterfly mimics monarch butterfly Fig. 5-5f, p. 109

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

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

16. 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

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

18. 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

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

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

21. Mutualism: Hummingbird and Flower Figure 5.8:Mutualism: This hummingbird benefits by feeding on nectar in this flower, and it benefits the flower by pollinating it. Fig. 5-8, p. 110

22. Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish Figure 5.9: Examples of mutualism: (a) Oxpeckers (or tickbirds) feed on parasitic ticks that infest large, thick-skinned animals such as the endangered black rhinoceros. (b) A clownfish gains protection and food by living among deadly, stinging sea anemones and helps to protect the anemones from some of their predators. Fig. 5-9, p. 111

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

24. 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.

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

26. Most Populations Live Together in Clumps or Patches • 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

27. Age structure Pre-reproductive age Reproductive age Post-reproductive age Populations Can Grow, Shrink, or Remain Stable • Population size governed by • Births • Deaths • Immigration • Emigration Population change = (births + immigration) – (deaths + emigration)

28. 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 • Exposure to too many competitors, predators or infectious diseases

29. Trout Tolerance of Temperature Figure 5.13: This diagram illustrates the range of tolerance for a population of organisms, such as trout, to a physical environmental factor—in this case, water temperature. Range of tolerance restrictions prevent particular species from taking over an ecosystem by keeping their population size in check. Question: For humans, what is an example of a range of tolerance for a physical environmental factor? Fig. 5-13, p. 113

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

31. No Population Can Grow Indefinitely: J-Curves and S-Curves • When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash

32. Exponential Growth, Overshoot, and Population Crash of a Reindeer Figure 5.17: This graph tracks the exponential growth, overshoot, and population crash of reindeer introduced onto the small Bering Sea island of St. Paul. When 26 reindeer (24 of them female) were introduced in 1910, lichens, mosses, and other food sources were plentiful. By 1935, the herd size had soared to 2,000, overshooting the island’s carrying capacity. This led to a population crash, when the herd size plummeted to only 8 reindeer by 1950. Question: Why do you think the sizes of some populations level offwhile others such as the reindeer in this example exceed their carrying capacities and crash? Fig. 5-17, p. 116

33. Species Have Different Reproductive Patterns MAJORITY MINORITY Reproduce later in life Small number of offspring with long life spans Young offspring grow inside mother Long time to maturity Protected by parents, and potentially groups Humans Elephants • Many, usually small, offspring • Little or no parental care • Massive deaths of offspring • Insects, bacteria, algae

34. Under Some Circumstances Population Density Affects Population Size DENSITY DEPENDENT FACTORS • Density-dependent population controls • Predation • Parasitism • Infectious disease • Competition for resources DENSITY INDEPENDENT FACTORS

35. Population Cycles for the Snowshoe Hare and Canada Lynx Figure 5.18: This graph represents the population cycles for the snowshoe hare and the Canadian lynx. At one time, scientists believed these curves provided evidence that these predator and prey populations regulated one another. More recent research suggests that the periodic swings in the hare population are caused by a combination of top-down population control—through predation by lynx and other predators—and bottom-up population control, in which changes in the availability of the food supply for hares help to determine their population size, which in turn helps to determine the lynx population size. (Data from D. A. MacLulich) Fig. 5-18, p. 118

36. Humans Are Not Exempt from Nature’s Population Controls BUBONIC PLAGUE: • 1st Outbreak – “Plague of Justinian” 542 AD, Eastern Roman Empire • Resulted in an estimated 25-50 million deaths over 2 centuries • 2nd Outbreak – “The Black Death” ~1347-early 1400’s • Resulted in the death of nearly a third of the human population of Europe and Asia • Last major outbreak in Europe 1813-1814

37. 3rd Outbreak: • 1855-1925 • Like the other 2 outbreaks, the plague originated in (or near) China, moved to India, the Hawaiian Islands and Australia • Resulted in an estimated 14 million deaths • The WHO declared the pandemic active until 1959 when worldwide casualties dropped to 200 per year

38. MALARIA: • The parasite responsible for malaria, P. falciparum,  has been in existence for 50,000–100,000 years however, the population size of the parasite did not increase until about 10,000 years ago, concurrently with advances in agriculture • WHO estimates that in 2015 there were 214 million new cases of malaria worldwide, resulting in 438,000 deaths. • Malaria has been so pervasive that it has driven the process of natural selection in multiple populations of Homo sapiens sapiensto include the allele for Sickle Cell Trait

39. POTATO BLIGHT: • Caused the Irish Potato Famine, 1845-1849 • Resulted in the death of ~1 million and the emigration of an estimated 2-3 million, mostly to the New World H1N1: • Spanish Flu Pandemic: 1918 (came in 2 waves/the 2nd deadlier than the 1st) • Swine Flu Pandemic: 2009-10 • The Americas hardest hit; current data suggest upwards of 405,000 died worldwide, either directly or from complications

40. HIV/AIDS: 1st case described in a diagnosis from 1959 First US case appears to have been in 1969 First clinical case in US in 1971 Originally people believed that only certain people were at risk for AIDS. Media named them the “four-H club:” • hemophiliacs, who received contaminated blood transfusions • homosexual men, who reported higher incidences of the disease • heroin users, and people who used drugs via injection • Haitian origin, many cases of AIDS were reported in Haiti

41. By 1978 it was estimated to be in ~5% of the US homosexual male population • President Ronald Regan says the word “AIDS” in public for the first time in September 1985; cumulative known deaths in the US…. 16,301 • It is estimated that by 1990, in the US alone, 600-900 thousand people were infected with HIV

42. 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. This can be either primary or secondary succession

43. Some Ecosystems Start from Scratch: Primary Succession • No soil in a terrestrial system • No bottom sediment in an aquatic system • Takes hundreds to thousands of years • Need to build up soils/sediments to provide necessary nutrients

44. Primary Ecological Succession Figure 5.19:Primary ecological succession: Over almost a thousand years, these plant communities developed, starting on bare rock exposed by a retreating glacier on Isle Royal, Michigan (USA) in northern Lake Superior. The details of this process vary from one site to another. Question: What are two ways in which lichens, mosses, and plants might get started growing on bare rock? Fig. 5-19, p. 119

45. Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession • Some soil remains in a terrestrial system • Some bottom sediment remains in an aquatic system • Ecosystem has been • Disturbed • Removed • Destroyed

46. Natural Ecological Restoration of Disturbed Land Figure 5.20:Natural ecological restoration of disturbed land: This diagram shows the undisturbed secondary ecological succession of plant communities on an abandoned farm field in the U.S. state of North Carolina. It took 150–200 years after the farmland was abandoned for the area to become covered with a mature oak and hickory forest. A new disturbance such as deforestation or fire would create conditions favoring pioneer species such as annual weeds. In the absence of new disturbances, secondary succession would recur over time, but not necessarily in the same sequence shown here. See an animation based on this figure at CengageNOW. Questions: Do you think the annual weeds (left) would continue to thrive in the mature forest (right)? Why or why not? Fig. 5-20, p. 120

47. Secondary Ecological Succession in Yellowstone Following the 1998 Fire Figure 5.21: These young lodgepole pines growing around standing dead trees after a 1998 forest fire in Yellowstone National Park are an example of secondary ecological succession. Fig. 5-21, p. 120

48. Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession • Primary and secondary succession • Tend to increase biodiversity • Increase species richness and interactions among species • Primary and secondary succession can be interrupted by • Fires • Hurricanes • Clear-cutting of forests • Plowing of grasslands • Invasion by nonnative species

49. Succession Doesn’t Follow a Predictable Path • Traditional view • Balance of nature and a climax community • Current view • Ever-changing mosaic of patches of vegetation • Mature late-successional ecosystems • State of continual disturbance and change

50. Living Systems Are Sustained through Constant Change • Inertia, persistence • Ability of a living system to survive moderate disturbances • Resilience • Ability of a living system to be restored through secondary succession after a moderate disturbance • Some systems have one property, but not the other: tropical rainforests