Chapter 34 and 36
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The document discusses several key topics related to ecology and populations: 1. Ecology is the study of organism interactions with their environments at different levels from individual to global. The biosphere is the global ecosystem encompassing all of Earth's environments. 2. Population ecology examines how and why populations change over time. Populations can experience exponential or logistic growth depending on environmental factors. 3. The human population has grown exponentially but is starting to slow down due to demographic transitions to lower birth rates in many countries. However, human impacts are already stressing the biosphere's capacity.
Chapter 34 and 36
- 1. Chapter 34 The Biosphere: An Introduction to Earth’s Diverse Environments 0
- 2. A Mysterious Giant of the Deep There are about 1,000 known species of squid But until recently, no one had reported on this “mystery squid”
- 3. Deep-sea submersibles Are allowing scientists to study uncharted depths of the ocean Figure A
- 4. At depths of up to 2,500 meters Scientists are observing new environments and a great variety of organisms Figure B Figure C
- 5. Ecology Is the scientific study of the interactions of organisms with their environments
- 6. 34.1 Ecologists study how organisms interact with their environment at several levels At the organismal level Ecologists may examine how one kind of organism meets the challenges of its environment Figure 34.1
- 7. At the population level Ecologists might study factors that limit population size At the community level An ecologist might focus on interspecies interactions
- 8. Ecosystem interactions involve Living (biotic) communities and nonliving (abiotic) physical and chemical factors
- 9. THE BIOSPHERE 34.2 The biosphere is the total of all of Earth’s ecosystems The biosphere Is the global ecosystem Figure 34.2A
- 10. Patchiness of the environment Characterizes the biosphere Figure 34.2B
- 11. CONNECTION 34.3 Environmental problems reveal the limits of the biosphere Human activities, including the widespread use of chemicals Affect all parts of the biosphere
- 12. Rachel Carson, a famous ecologist Was one of the first people to perceive the global dangers of pesticide use Figure 34.3
- 13. 34.4 Physical and chemical factors influence life in the biosphere Abiotic factors determining the biosphere’s structure and dynamics include Solar energy, water, temperature, wind, and disturbances Figure 34.4
- 14. 34.5 Organisms are adapted to abiotic and biotic factors by natural selection Unique adaptations Allow the survival of organisms in particular habitats Figure 34.5
- 15. Biotic factors, such as predation and competition Can lead to the evolution of adaptations by natural selection
- 16. 34.6 Regional climate influences the distribution of biological communities Most climatic variations Are due to the uneven heating of Earth’s surface as it orbits the sun Figure 34.6A Low angle of incoming sunlight Sunlight strikes most directly Low angle of incoming sunlight Atmosphere 60ºS South Pole Tropic of Capricorn 30ºS 0º (equator) 30ºN Tropic of Cancer North Pole 60ºN
- 17. The tilt of the Earth’s axis Causes the changes of the seasons in the northern and southern hemispheres June solstice (Northern Hemisphere tilts toward sun) March equinox (equator faces sun directly) Constant tilt of 23.5º September equinox December solstice (Northern Hemisphere tilts away from sun) Figure 34.6B
- 18. The uneven heating of the Earth Also sets up patterns of precipitation and prevailing winds Figure 34.6C, D Descending dry air absorbs moisture Trade winds Ascending moist air releases moisture Trade winds Descending dry air absorbs moisture Doldrums Temperate zone Tropics Temperate zone 30º 23.5º 0º 23.5º 30º 60ºN 30ºN 30ºS
- 19. Ocean currents Influence coastal climate Fresno 104º Paso Robles 93º Bakersfield 106º Death Valley 119º Pacific Ocean Santa Barbara 75º Los Angeles (Airport) 74º San Diego 75º 40 miles San Bernardino 101º Riverside 91º Palm Springs 104º Burbank 86º Santa Ana 84º Key 70s (ºF) 80s 90s 100s 110s Figure 34.6E
- 20. Landforms such as mountains Affect rainfall Pacific Ocean Coast Range Wind direction Sierra Nevada East Figure 34.6F
- 21. AQUATIC BIOMES 34.7 Oceans occupy most of Earth’s surface Several characteristics shape ocean communities Light, distance from shore, and the availability of nutrients
- 22. The intertidal zone, an oceanic zone Is the area of shore where the ocean meets the land Figure 34.7A
- 23. Oceanic zones also include The pelagic and benthic zones Figure 34.7B Intertidal zone Photic zone 0 200 m Continental shelf 2,500–6,000 m Benthic zone (seafloor) Pelagic zone Aphotic zone
- 24. Coral reefs Are found in warm waters above continental shelves Figure 34.7C
- 25. Estuaries Are productive areas where rivers flow into the ocean Figure 34.7D
- 26. 34.8 Freshwater biomes include lakes, ponds, rivers, streams, and wetlands Factors that shape lake and pond communities include Light, temperature, and the availability of nutrients and dissolved oxygen
- 27. Abiotic factors change from the source of a river to its mouth And communities vary accordingly Figure 34.8A
- 28. Wetlands include Marshes and swamps Figure 34.8B
- 29. TERRESTRIAL BIOMES 34.9 Terrestrial biomes reflect regional variations in climate Temperature and rainfall Mainly determine the terrestrial biomes
- 30. Major terrestrial biomes 30ºN Tropic of Cancer Equator Tropic of Capricorn 30ºS Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Tundra High mountains Polar ice Figure 34.9
- 31. 34.10 Tropical forests cluster near the equator Tropical rain forests Are the most diverse ecosystem Figure 34.10
- 32. 34.11 Savannas are grasslands with scattered trees Savannas Are dry and warm Figure 34.11
- 33. 34.12 Deserts are defined by their dryness Deserts Are the driest biomes Figure 34.12
- 34. 34.13 Spiny shrubs dominate the chaparral The chaparral Is a shrubland with cool, rainy winters and dry, hot summers Figure 34.13
- 35. 34.14 Temperate grasslands include the North American prairie Temperate grasslands Are found where winters are cold Figure 34.14
- 36. 34.15 Broadleaf trees dominate temperate forests Temperate broadleaf forests grow throughout midlatitude regions Where there is sufficient moisture to support the growth of large trees Figure 34.15
- 37. 34.16 Coniferous forests are often dominated by a few species of trees The northern coniferous forest, or taiga Is found where there are short summers, and long, snowy winters Figure 34.16
- 38. 34.17 Long, bitter-cold winters characterize the tundra Arctic tundra Is a treeless biome characterized by extreme cold, wind, and permafrost Figure 34.17
- 39. Alpine tundra Occurs above the treeline on high mountains
- 40. TALKING ABOUT SCIENCE 34.18 Ecologist Ariel Lugo studies tropical forests in Puerto Rico The Luquillo Experimental Forest Allows ecologists to study the effects of disruption on tropical forests Figure 34.18A, B
- 41. Chapter 36 Population Dynamics 0
- 42. The Spread of Shakespeare’s Starlings The European Starling Has become an abundant and destructive pest in North America 0 European starling
- 43. Starling populations have become very successful And spread throughout North America since their introduction in 1890 0 Current 1955 1945 1935 1925 1915 1905 1925 1935 1945 1955 Current The spread of starlings across North America
- 44. Population ecology Is concerned with changes in population size and the factors that regulate populations over time 0
- 45. 36.1 Population ecology is the study of how and why populations change A population Is a group of individuals of a single species that occupy the same general area 0
- 46. POPULATION STRUCTURE AND DYNAMICS 36. 2 Density and dispersion patterns are important population variables Population density Is the number of individuals of a species per unit of area or volume 0
- 47. Environmental and social factors Influence the spacing of individuals in various dispersion patterns: clumped, uniform, or random 0 Figure 36.2A Figure 36.2B
- 48. 36.3 Life tables track mortality and survivorship in populations Life tables and survivorship curves Predict an individual’s statistical chance of dying or surviving during each interval of the individual’s lifetime 0 Table 36.3
- 49. The three types of survivorship curves Reflect species’ differences in reproduction and mortality 0 Percentage of survivors (log scale) 100 10 1 0.1 0 50 100 III II I Percentage of maximum life span Figure 36.3
- 50. 36.4 Idealized models help us understand population growth 0
- 51. The Exponential Growth Model Exponential growth Is the accelerating increase that occurs when growth is unlimited 0
- 52. The equation G rN describes this J-shaped curve G the population growth rate r an organism’s inherent capacity to reproduce N the population size 0 Figure 36.4A Time Number of Cells 0 minutes 20 40 60 80 100 120 (= 2 hours) 3 hours 4 hours 8 hours 12 hours 1 2 4 8 16 32 64 512 4,096 16,777,216 68,719,476,736 = 2 0 = 2 1 = 2 2 = 2 3 = 2 4 = 2 5 = 2 6 = 2 9 = 2 12 = 2 24 = 2 36 Number of bacterial cells ( N ) 70 60 50 30 40 20 10 0 0 20 40 60 80 100 120 140 G = r N Time (min)
- 53. Limiting Factors and the Logistic Growth Model Limiting factors Are environmental factors that restrict population growth 0 Breeding male fur seals (thousands) 10 8 6 4 2 0 1915 1925 1935 1945 Year Figure 36.4B
- 54. Logistic growth Is the model that represents the slowing of population growth as a result of limiting factors Levels off at the carrying capacity, which is the number of individuals the environment can support 0 Figure 36.4C Number of individuals ( N ) K 0 Time G = r N G = r N (K – N) K
- 55. The equation G rN(K – N)/K describes a logistic growth curve Where K carrying capacity and ( K – N )/ K accounts for the leveling off of the curve 0
- 56. 36.5 Multiple factors may limit population growth As a population’s density increases Factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both 0 4.0 3.6 3.8 3.4 3.2 3.0 2.8 0 10 20 30 40 50 60 70 80 Density of females Clutch size Figure 36.5A
- 57. Abiotic factors such as weather May limit many natural populations 0 Exponential growth Sudden decline Number of aphids Apr May Jun Jul Aug Sep Oct Nov Dec Figure 36.5B
- 58. Most populations Are probably regulated by a mixture of factors, and fluctuations in numbers are common 0 Time (years) 1975 1980 1985 1990 1995 2000 0 20 40 80 60 Number of females Figure 36.5C
- 59. 36.6 Some populations have “boom-and-bust” cycles Some populations Undergo regular boom-and-bust cycles of growth and decline 0 Figure 36.6 160 120 80 40 0 1850 1875 1900 1925 9 6 3 0 Snowshoe hare Lynx Hare population size (thousands) Lynx population size (thousands) Year
- 60. 36.7 Evolution shapes life histories An organism’s life history Is the series of events from birth through reproduction to death LIFE HISTORIES AND THEIR EVOLUTION 0
- 61. Populations with so-called r -selection life history traits Produce many offspring and grow rapidly in unpredictable environments 0 Figure 36.7A
- 62. Populations with K -selected traits Raise few offspring and maintain relatively stable populations 0
- 63. Life history traits Are shaped by natural selection 0 Experimental transplant of guppies Predator: Killifish; preys mainly on small, immature guppies Guppies: Larger at sexual maturity than those in pike-cichlid pools Predator: Pike-cichlid; preys mainly on large, mature guppies Guppies: Smaller at sexual maturity than those in killifish pools Figure 36.7B
- 64. 36.8 Principles of population ecology have practical applications Principles of population ecology Are useful in managing natural resources CONNECTION 0 900 800 700 600 500 400 300 200 100 0 1960 1970 1980 1990 2000 Yield (thousands of metric tons) Figure 36.8
- 65. THE HUMAN POPULATION CONNECTION 36.9 Human population growth has started to slow after centuries of exponential increase The human population Has been growing almost exponentially for centuries, standing now at about 6.4 billion 0 The Plague 6 5 4 3 2 1 0 8000 B.C. 4000 B.C. 3000 B.C. 2000 B.C. 1000 B.C. 0 1000 A.D. 2000 A.D. Human population size (billions) Figure 36.9A
- 66. The ecological footprint Represents the amount of land per person needed to support a nation’s resource needs 0 16 14 12 10 8 6 4 2 0 0 2 4 6 8 10 12 14 16 Available ecological capacity (ha per person) Ecological footprint (ha per person) Japan UK Spain Germany Netherlands Norway USA World China India Sweden Canada Australia New Zealand Figure 36.9B
- 67. The ecological capacity of the world May already be smaller than the population’s ecological footprint 0 Traffic in downtown Cairo, Egypt Manhattan, New York City Refugee camp in Zaire Figure 36.9C
- 68. 36.10 Birth and death rates and age structure affect population growth The demographic transition Is the shift from high birth rates and death rates to low birth rates and death rates 0 50 40 30 20 10 0 1900 1925 1950 1975 2000 2025 2050 Year Birth rate Death rate Birth or death rate per 1,000 population Figure 36.10A
- 69. The age structure of a population Is the proportion of individuals in different age-groups Affects its future growth 0 Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 8 4 6 2 0 2 4 6 8 6 4 2 0 2 4 6 6 4 2 0 2 4 6 Percent of population Percent of population Percent of population Primary reproductive ages Rapid growth Slow growth Decrease Afghanistan United States Italy Male Female Male Female Male Female Figure 36.10B
- 70. Increasing the status of women May help to reduce family size 0