1 / 55

Biodiversity, Species Interactions, and Population Control

Biodiversity, Species Interactions, and Population Control. Chapter 5. Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction?. Hunted nearly to extinction in native California coast habitat Partial recovery Why care about sea otters? Ethics

matty
Download Presentation

Biodiversity, Species Interactions, and Population Control

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


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

  2. Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction? • Hunted nearly to extinction in native California coast habitat • Partial recovery • Why care about sea otters? • Ethics • Keystone species in kelp forests • Tourism dollars

  3. Science Focus: Why Should We Care about Kelp Forests? • Kelp forests: biologically diverse marine habitat • Renewable resource: harvested for algin, a thickening agent used in toothpaste, cosmetics, ice cream, etc. • Major threats to kelp forests • Sea urchins (main food source for dwindling sea otter populations) • Pollution from water run-off • Global warming

  4. Southern Sea Otter

  5. Purple Sea Urchin

  6. Science Focus: Why Are Protected Sea Otters Making a Slow Comeback? • Otters are k-selected and face several limiting factors: • Low biotic potential • Prey for orcas • Cat parasites • Thorny-headed worms • Toxic algae blooms • PCBs and other toxins • Oil spills

  7. Population Size of Southern Sea Otters Off the Coast of So. California (U.S.)

  8. 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.

  9. Species Interact in Five Major Ways • Interspecific Competition • Predation • Parasitism • Mutualism • Commensalism • Interactions helps limit population growth (principle of sustainability)

  10. Most Species Compete with One Another for Certain Resources • Competition • Greater niche overlap=greater competition • Niche overlap- two species complete with one another for the same resource • Competitive exclusion principle- no two species can occupy the same niche for very long, especially in the same ecosystem

  11. 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 **predators stalk and kill there prey! Different from parasites!**

  12. Most Consumer Species Feed on Live Organisms of Other Species (2) • Prey may avoid capture by • Camouflage • Chemical warfare • Warning coloration • Mimicry • Deceptive looks • Deceptive behavior

  13. Most Consumer Species Feed on Live Organisms of Other Species (3) • Edward O. Wilson • If it is small and strikingly beautiful, it is probably poisonous • If it is strikingly beautiful and easy to catch, it is probably deadly • Prey Adaptations • Warning coloration • Mimicry

  14. (a) Span worm (b) Wandering leaf insect (c) Bombardier beetle (d) Foul-tasting monarch butterfly (f) Viceroy butterfly mimics monarch butterfly (e) Poison dart frog (g) Hind wings of Io moth resemble eyes of a much larger animal. (h) When touched, snake caterpillar changes shape to look like head of snake. Stepped Art Fig. 5-2, p. 103

  15. Predator and Prey Species Can Drive Each Other’s Evolution • Intense natural selection pressures between predator and prey populations • Prey organisms will experience natural selection in their traits that keep them from getting eaten • Predator organisms will experience natural selection in traits that make them better hunters/stalkers • Co-evolution- changes in the gene code of one species lead to changes in another species • Constant race

  16. Coevolution: A Langohrfledermaus Bat Hunting a Moth

  17. Some Species Feed off Other Species by Living on or in Them • Parasitism • Increases Species Richness • Keeps host populations in check • Parasite-host interaction may lead to co-evolution • Ex: malaria parasites have developed a defense against being swept into the spleen (thousands of different version of a sticky protein)

  18. Parasitism: Tree with Parasitic Mistletoe, Trout with Blood-Sucking Sea Lampreys

  19. In Some Interactions, Both Species Benefit • Mutualism • Nutrition and protection relationship • Gut inhabitant mutualism

  20. Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish

  21. In Some Interactions, One Species Benefits and the Other Is Not Harmed • Commensalism • Epiphytes or “air plants” attach to tree trunks or branches (solid surface, more sunlight), without leaching nutrients from the tree • Birds nesting in trees

  22. Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree

  23. 5-2 How Can Natural Selection Reduce Competition between Species? • Concept 5-2 Some species develop adaptations that allow them to reduce or avoid competition with other species for resources.

  24. Some Species Evolve Ways to Share Resources • Resource partitioning- species competing for the same resource find a way to share it • Reduce niche overlap • Use shared resources at different • Times • Places • Ways

  25. Competing Species Can Evolve to Reduce Niche Overlap

  26. Sharing the Wealth: Resource Partitioning

  27. Specialist Species of Honeycreepers

  28. 5-3 What Limits the Growth of Populations? • Concept 5-3 No population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources.

  29. Populations Have Certain Characteristics (1) • Populations differ in • Distribution • Numbers • Age structure • Population dynamics-study of how these factors change in response to environmental conditions

  30. Populations Have Certain Characteristics (2) • Changes in population characteristics due to: • Temperature • Presence of disease organisms or harmful chemicals • Resource availability • Arrival or disappearance of competing species

  31. Most Populations Live Together in Clumps or Patches (1) • Population distribution • Clumping • Uniform dispersion • Random dispersion • 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 • Temporary groups for mating and caring for young

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

  33. Populations Can Grow, Shrink, or Remain Stable (2) • Age structure • Pre-reproductive age • Reproductive age • Post-reproductive age • Should be able to predict population changes for the future based on age structure • ***review age structure shape of rapid growth, slow, growth, stable population, from biology (also in Chapter 6)

  34. No Population Can Grow Indefinitely: J-Curves and S-Curves (1) • Biotic potential- capacity for growth • Low (large animals) • High (tiny organism—microbes) • Intrinsic rate of increase (r)- The rate at which a pop would grow with unlimited resources • Individuals in populations with high r • Reproduce early in life • Have short generation times • Can reproduce many times • Have many offspring each time they reproduce

  35. No Population Can Grow Indefinitely: J-Curves and S-Curves (2) • Size of populations limited by • Light • Water • Space • Nutrients • Exposure to too many competitors, predators or infectious diseases

  36. No Population Can Grow Indefinitely: J-Curves and S-Curves (3) • Environmental resistance- combinations of all factors that limit population growth • Carrying capacity (K)- maximum population of a species a habitat can sustain • Biotic potential + Environmental Resistance • Exponential growth (J) • Logistic growth (S)

  37. No Population Can Continue to Increase in Size Indefinitely

  38. Logistic Growth of a Sheep Population on the island of Tasmania, 1800–1925

  39. When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash • Carrying capacity is not static—changes as resource availability changes! • Reproductive time lag may lead to overshoot • Dieback (crash) • Births decrease • Deaths increase • Damage may reduce area’s carrying capacity

  40. Exponential Growth, Overshoot, and Population Crash of a Reindeer

  41. Species Have Different Reproductive Patterns • r-Selected species, opportunists • Reproduce early in life, small org., large numbers, no parenting , short life spans • K-selected species, competitors • Reproduce later in life, large org., small numbers, parenting, long life spans

  42. Carrying capacity K K species; experience K selection Number of individuals r species; experience r selection Time Fig. 5-14, p. 112

  43. Genetic Diversity Can Affect the Size of Small Populations • Founder effect- individuals of a population colonize new area • Demographic bottleneck- few individuals survive a catastrophe • Genetic drift- random changes in genes that can lead to unequal reproductive success • Inbreeding- individuals of a small population mate with one another • Minimum viable population size- an estimate of the number of individuals needed for long term survival

  44. Under Some Circumstances Population Density Affects Population Size • Density-dependent population controls • Predation • Parasitism • Infectious disease • Competition for resources

  45. Several Different Types of Population Change Occur in Nature • Stable • Irruptive • Cyclic fluctuations, boom-and-bust cycles • Top-down population regulation- predation • Bottom-up population regulation – scarcity of a resource. • Irregular

  46. Population Cycles for the Snowshoe Hare and Canada Lynx

  47. Humans Are Not Exempt from Nature’s Population Controls • Ireland • Potato crop in 1845 • Bubonic plague • Fourteenth century • AIDS • Global epidemic

  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 • Lyme disease • Deer-vehicle accidents • Eating garden plants and shrubs • Ways to control the deer population

  49. 5-4 How Do Communities and Ecosystems Respond to Changing Environmental Conditions? • Concept 5-4 The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession.

  50. Communities and Ecosystems Change over Time: Ecological Succession • Natural ecological restoration • Primary succession • Starting from scratch • Secondary succession • Soil in existence (“natural re-purposing”) • Ecosystem has been: • Disturbed (human development spreads) • Removed (draining wetlands) • Destroyed (forest fire)

More Related