Biodiversity, Species Interactions, and Population Control

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

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 • Keystone species • Tourism dollars

3. Case Study: Sea Otters Are They Back From the Brink of Extinction (a)Southern sea otter (c) Kelp bed (b) Sea Urchin

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. Most Species Compete with One Another for Certain Resources • Competition the struggle among organisms, both of the same and of different species, for food, space, and other vital requirements. • Competitive exclusion principle The principle that when two species compete for the same critical resources within an environment, one of them will eventually outcompete and displace the other. The displaced species may become locally extinct, by either migration or death, or it may adapt to a sufficiently distinct niche within the environment so that it continues to coexist noncompetitively with the displacing species.

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

7. Interspecific competition • Competition between two different species • For food, sunlight, water, soil, space • One species may migrate or shift feeding habits or face extinction • Example-native ants and nonnative fire ants • Intraspecific competition • competition between members of the same species

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

9. PREDATION

14. Most Consumer Species Feed on Live Organisms of Other Species • Prey may avoid capture by • Camouflage • Chemical warfare • Warning coloration • Mimicry • Deceptive looks • Deceptive behavior • Swift movement • Shell

15. Some ways prey species avoid their prey Bombardier beetle Span worm Wandering leaf insect Foul-tasting monarch butterfly When touched, the snake caterpillar changes shape to look like the head of a snake Poison dart frog Viceroy butterfly mimics monarch butterfly Hind wings of moth resemble eyes of a much larger animal

22. Parasitism, Mutualism, Commensalism

23. Parasitism Live on or in another species Host is harmed Ex. Tapeworms, ticks, fleas, mosquitoes, candiru (vampire fish)

24. Mutualism (benefits both species) Pollination mutualism (between flowering plants and animals) Nutritional mutualism Lichens grow on trees Birds/rhinos- nutrition and protection Clownfish/sea anemones Inhabitant mutualism Vast amount of organisms like bacteria in an animal’s digestive tract Termites and bacteria in gut

25. . Coral Reefs- The corals get food and the zooxanthellae (algae) get protection. zooxanthellae

26. Yucca and Yucca Moth • Yucca’s only pollinator is the yucca moth. Hence entirely dependent on it for dispersal. • Yucca moth caterpillar’s only food is yucca seeds. • Yucca moth lives in yucca and receives shelter from plant. • Example of co evolution

27. Figure 8-10Page 155 Oxpeckers and black rhinoceros Clown fish and sea anemone Examples of Mutualism Mycorrhizae fungi on juniper seedlings in normal soil Lack of mycorrhizae fungi on juniper seedlings in sterilized soil

28. Commensalism Helps one species but does nothing for the other Ex. Redwood sorrel grows in shade of redwood - Humans and Eyelash Mites

29. Science Focus: Why Should We Care about Kelp Forests? • Kelp forests: biologically diverse marine habitat • Major threats to kelp forests • Sea urchins • Pollution from water run-off • Global warming

30. 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.

31. Some Species Evolve Ways to Share Resources • Resource partitioning • Reduce niche overlap • Use shared resources at different • Times • Places • Ways

32. Resource partitioning Evolve more specialized traits Five species of common insect-eating warblers in the Spruce forests of Maine

33. 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.

34. Characteristics of a Population • Population - individuals inhabiting the same area at the same time • Population Dynamics: is the study of how population change due to • Population Size- number of individuals • Population Density - population size in a certain space at a given time • Population Dispersion- spatial pattern in habitat • Age distribution - proportion of individuals in each age group in population

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

36. Population Size • Natality • Number of individuals added through reproduction • Crude Birth Rate - Births per 1000 • Total Fertility Rate – Average number of children born alive per woman in her lifetime • Mortality • Number of individuals removed through death • Crude Death Rate- Deaths per 1000

37. Population Density • Population Density (or ecological population density) is the amount of individuals in a population per unit habitat area • Some species exist in high densities - Mice • Some species exist in low densities - Mountain lions • Density depends upon • social/population structure • mating relationships • time of year

38. Population Dispersion Population dispersion is the spatial pattern of distribution There are three main classifications Clumped: individuals are lumped into groups ex. Flocking birds or herbivore herds due to resources that are clumped or social interactions most common http://www.johndarm.clara.net/galleryphots/

39. 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 • Temporary groups for mating and caring for young

40. Uniform: Individuals are regularly spaced in the environment - ex. Creosote bush due to antagonism between individuals, or do to regular spacing of resources rare because resources are rarely evenly spaced Random: Individuals are randomly dispersed in the environment ex. Dandelions due to random distribution of resources in the environment, and neither positive nor negative interaction between individuals rare because these conditions are rarely met www.agry.purdue.edu/turf/ tips/2002/clover611.htm Population Dispersion http://www.calflora.net/bloomingplants/creosotebush2.html

41. Age Structure • The age structure of a population is usually shown graphically • The population is usually divided up into prereproductives, reproductives and postreproductives • The age structure of a population dictates whether is will grow, shrink, or stay the same size

42. Age Structure Diagrams Positive Growth Zero Growth Negative Growth (ZPG) Pyramid Shape Vertical Edges Inverted Pyramid

43. Four variables influencing growth Births Deaths Immigration Emigration Increase  by birth & immigration Decrease  death & emigration Population change= (Birth + Immigration)- (Death + Emigration)

44. No Population Can Grow Indefinitely: J-Curves and S-Curves (1) • Biotic potential -is the population’s capacity for growth • Low generally large animals elephant and blue whales • High small individuals like bacteria and insects • Intrinsic rate of increase (r)is the rate of population growth with unlimited resources.

45. Rapidly growing populations have four characteristics (high r) • Reproduction early in life • Short periods between generations • Long reproductive lives • Multiple offspring each time they reproduce • A single house fly could total 5.6 trillion house flies within 13 months

46. 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

47. Environmental Resistance • Consists of all factors that act to limit the growth of a population • Abiotic Contributing Factors: • Unfavorable light • Unfavorable Temperatures • Unfavorable chemical environment - nutrients • Biotic Contributing Factors: • Low reproductive rate • Specialized niche • Inability to migrate or disperse • Inadequate defense mechanisms • Inability to cope with adverse conditions

49. Limits on population growth • Carrying capacity [K]determined by biotic potential & environmental resistance • This is the # of a species’ individuals that can be sustained indefinitely in a specific space • As a population reaches its carrying capacity, its growth rate will decrease because resources become more scarce.