1. Ecology Study of the interactions of organisms with other
organisms and with the physical environment

2. Figure 42.1 The Hierarchy of Ecological Systems

3. Concept 42.1 Ecological Systems Vary in Space and over Time
At any given time, an ecological system is potentially unique.
In the human gut, the microbial species vary from person to person and with diet.
The host’s genotype and diet affect the gut environment from the bacterial point of view; and the bacteria influence their environment, which includes the host.
Some health disorders may be treatable by manipulating the gut bacterial community.
LINK Figure 12.7 Scientists can analyze complex microbial ecosystems by sequencing DNA present in environmental samples

4. ecosystem
abiotic
biotic

5. Biodiversity

6. Intermediate Disturbance Hypothesis

7. Ostriches are nomadic, wandering in small groups.
Populations
Groups of organisms of the same species that live within a given area
Key characteristics:
Dispersion patterns
Population density
Growth rate
Ostriches are nomadic, wandering in small groups.
Populations
A population is a group of individuals of the same species living within a designated area at one time. The boundary of the population may be physical—such as a mountain range—or defined by a scientist for purposes of study.
Demography is the statistical study of populations. Three important aspects of population structure are: dispersion patterns or spacing, population density, and growth rate.
References
Campbell, N.E. & Reece, J.B. (2002). Biology, (6th ed.). San Francisco: Benjamin Cummings.
Image Reference
NOVA Development Corp. (1995) Birds #2289. Art Explosion, Volume 2 Clip Art
NOVA Development Corp. (1995) New England #57. Art Explosion, Volume 2 Clip Art
Aspen trees are quick to pioneer areas that have been disturbed by fire.

8. Dispersion Patterns Within Populations
Three common patterns of population distribution are:
Dispersion Patterns Within Populations
The arrangement, or dispersion, of individuals in relation to one another within a given area is one key characteristic of population study, as it reflects interactions among the population and the environment. Three patterns of population dispersion are clumped, evenly spaced, and random.
The most frequent pattern of distribution in a population is clumped. Individuals are clustered together in groups in response to uneven distribution of resources, tendency of offspring to remain with parents, or some type of social order. Clumping also may be linked with defense (safety in numbers) or mating behavior. In plants, soil type, availability of water or the manner in which the plant reproduces may favor clumped distribution patterns.
Evenly spaced distributions, in which members of the population maintain a minimum distance from one another, generally indicates strong intraspecific competition. In plant populations, this could result from competition for water, sunlight, or available nutrients, while among animals, even spacing indicates strong territoriality.
Random spacing is the least common pattern of distribution found in populations. It usually occurs because members of a species do not frequently interact with one another or are not heavily influenced by the microenvironments within their habitat.
References
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Raven, P. H. & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.
Image Reference
Young, M. (2004). Dispersion patterns within populations. Houston, TX: Baylor College of Medicine, Center For Educational Outreach.

9. Population Density
Population density is total population size per unit of area.
Population densities depend on:
Interactions within the environment
Quality of habitat
Density dependent factors
Density independent factors
Carrying capacity is the maximum number of organisms that can be supported in a given habitat.
Population size can be measured by several sampling techniques.
Population Density
Population density is a measure of the number of individuals of the same species living in a designated unit of space. It is influenced by relationships among organisms, movement of individuals in and out of the habitat, resources, and abiotic environmental factors (such as climate). Fluctuations in population density can be indications of changes in the environment.
Carrying capacity is the maximum number of organisms in a population that can be supported by a particular habitat. Many factors determine carrying capacity, some of which are influenced by the density of the population, while others are not. Density-dependent factors in an environment might be influenced by available food, water, and shelter. Density-independent factors include all facets of weather and climate, such as droughts, storms, and volcanic eruptions.
It often is difficult to determine the size of a population because of the wide range of the habitat or mobility of the organisms. In such cases, ecologists use a variety of sampling methods. For instance, a designated area of study might be sectioned into grids or plots. Numbers of organisms counted in selected grids are extrapolated to estimate the total population size. Mark-and-recapture is another method used to estimate population size in large geographic areas. Traps are set in the study area. Trapped organisms are tagged and released. After a period of time, traps are set again, and calculations are made based on the number of marked organisms that are recaptured.
Total population = total size of 2nd sample X marked # in 1st catch
marked # recaptured in 2nd catch
References:
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Ricklefs, R. E. & G. L. Miller. (2000). Ecology (4th ed.). New York: W.H. Freeman and Co.

10. Population Growth Exponential vs. Logistical Growth Population Growth
Birth, death, immigration, and emigration rates factor into the growth rate of a population. Two simple models of population growth are the exponential model and the logistical model.
The growth pattern for a population with unlimited resources is exponential and represented by a “J” shaped growth curve. A population that is growing exponentially increases in a geometric pattern (for example, 2, 4, 8, 16, 32, etc.). In the formula dN/dt = riN, dN/dt is the rate of change in the number of individuals at any instant in time and ri represents the innate capacity for growth of the population (biotic potential) when in an unlimited environment. Populations that are introduced to a new environment or are recovering from a catastrophic event (such as a fire) usually exhibit “J” shaped growth curves.
Population growth eventually reaches a limit imposed by factors such as light, space, nutrients, or water. Carrying capacity (K) is the maximum number of individuals a particular habitat can support. Growth in a logistical model slows as it approaches the carrying capacity of the environment and forms an “S” shaped growth curve. In reality, populations sometimes will overshoot K, followed by a rapid decline, until conditions for growth are restored.
References
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Raven, P. H. & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.
Image Reference
Young, M. (2004). Exponential vs. logistical growth graph. Houston, TX: Baylor College of Medicine, Center For Educational Outreach.

11. Survivorship in Populations
Survivorship curves are graphic representations of the age structure of a given population. They are used to predict the future growth of the population. Type I curves reflect relatively low death rates early in life and through midlife, with a sharp increase in death rate among older-age groups (e.g., humans). Type II curves illustrate a fairly even mortality rate throughout the life span of the organism (e.g., birds). Populations with high death rates early in life followed by a sharp decline of death rates for the survivors are represented by Type III survivorship curves (e.g., fish and many insect populations).
References
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Ricklefs, R. E. & G. L. Miller. (2000). Ecology (4th ed.). New York: W.H. Freeman and Co.
Image Reference
Young, M. (2004). Survivorship graph. Houston, TX: Baylor College of Medicine, Center For Educational Outreach.

12. Reproductive Strategies
r- Selected (maximum growth rate, below carrying capacity)
Early reproduction
Short life span
High mortality rate
Little or no parental care
Large investment in producing large numbers of offspring
Below carrying capacity
Examples:
Bony fish
Grasshoppers
K-Selected (maximizes population size near carrying capacity)
Late reproduction
Long life span
Low mortality rate
Extensive parental care
Greater investment in maintenance and survival of adults
At or near carrying capacity
Examples:
Sharks
Elephants
Reproductive Strategies
In an uncrowded environment, such as a recently abandoned crop field, natural selection pressure tends to favor populations that invest heavily in offspring, have shorter life spans, capacity for widespread dispersion, and usually provide little or no parental care for offspring (for example, mosquitoes, ragweed, or mice). These populations tend to increase exponentially and often are referred to as r-strategist, where r refers to the intrinsic rate of growth of the population. In contrast, crowed conditions favor organisms with lower rates of population growth, but improved capabilities to utilize and compete for resources. These populations maintain themselves at levels close to carrying capacity (K) and are referred to as K-strategist.
Biologist refer to the types of selection pressure placed on populations as r-selection, if individuals that reproduce rapidly and abundantly are favored, and as K-selection, if individuals that compete well in crowded conditions are favored over time.
References
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Odum, E. (1997). Ecology: A Bridge Between Science and Society. Sunderland, MA: Sinauer Associates, Inc.
Raven, P. H. & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.

13. Limits on Population Growth
Density Dependent Limits
Food
Water
Shelter
Disease
Density Independent Limits
Weather
Climate
Water and shelter are
critical limiting factors in
the desert.
Limits on Population Growth
Carrying capacity (K) is the maximum number of organisms of a population that can be supported by a particular habitat. As population numbers approach the carrying capacity of an environment, in other words as density increases, competition for resources is amplified. Density-dependent factors in an environment include available food, nutrients in the soil, water, and shelter, among many others. The buildup of metabolic wastes also increases with density and adversely affects many populations as well.
Weather, climate, and human activities can be density-independent factors which affect the environment. In the case of catastrophic events or the pressure of toxins, populations are affected regardless of size. Populations recover at different rates, some even experiencing a permanent decline after a major change in the environment.
References
Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings.
Raven, P. H. & Johnson, G. B. (2002). Biology (6th ed.). McGraw-Hill.
Image Reference
NOVA Development Corp. (1995) Birds #2516. Art Explosion, Volume 2 Clip Art
NOVA Development Corp. (1995) Wilderness #319. Art Explosion, Volume 2 Clip Art
Fire is an example of a
Density independent
Limiting factor.

14. Figure I shows the growth of an algal species in a flask of sterilized pond water. If phosphate is added as indicated, the growth curve changes as shown in Figure II.
Which of the following is the best prediction of the algal growth if nitrate is added instead of phosphate? a. c. b. d.

15. Use the graph above to calculate the mean rate of population growth (individuals per day) between day 3 and day 5. Give your answer to the nearest whole number.

16. A population of microscopic eukaryotic organisms growing in a large flask had the growth pattern shown.
In one paragraph, explain the biological factors that determine the shape of the growth pattern shown above in both period 1 and period 2.

17. Predator/ Prey

19. Use the graph above to calculate the lag time in months between the change in the densities of the prey and the predator populations. Give your answer to the nearest tenth of a month.

20. (Camouflage)

22. Aposematic Coloration
(warning coloration)
Don't Touch!!!!

24. Batesian Mimicry
monarch
viceroy
king snake
coral snake

28. parasitism
commensalism
mutualism

31. Primary succession

32. Secondary succession

33. Climax Community

35. The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees?
(A) Eventually the other trees grow taller than the oak trees and form a dense canopy that shades the understory.
(B) Oak trees alter the pH of the soil, making the forest better suited for shrubs and other trees.
(C) Roots of shrubs proliferate in the soil of the forest and prevent the oak trees from obtaining water.
(D) Oak trees succumb to environmental pollutants more readily than do either the shrubs or the other trees.

38. Assume there are 50,000 joules (J) of energy available in trophic level II in the figure. According to the conventional model of energy flow in ecosystems, which of the following statements correctly describes the flow of energy in the system?
(A) Trophic level I generates a maximum of 50,000 J of energy.
(B) Trophic level I has approximately 5,000 J of available energy.
(C) Trophic level III has approximately 50 J of available energy.
(D) Trophic level IV has approximately 500 J of available energy.

39. Break down organic waste
Detritivores
Break down organic waste

43. What percent of the biomass in the forest community represented above is tied up in the shrub layer? Give your answer to the nearest whole number.

44. The following is a food web for a meadow habitat that occupies 25
The following is a food web for a meadow habitat that occupies 25.6 km2. The primary producers’ biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km2.
Developers have approved a project that will permanently reduce the primary producers’ biomass by 50 percent and remove all rabbits and deer.
Which of the following is the most likely result at the completion of the project?
(A) The biomass of coyotes will be 6 kg, and the biomass of hawks will be 0.5 kg.
(B) The biomass of coyotes will be dramatically reduced.
(C) The coyotes will switch prey preferences and outcompete the hawks.
(D) There will be 50 percent fewer voles and 90 percent fewer hawks.

45. The food web above represents feeding relationships in a biological community near a deep-sea hydrothermal vent. Hydrothermal vents are geysers on the seafloor that gush super-heated, mineral-rich water. The seawater surrounding hydrothermal vents typically contains carbon dioxide , molecular hydrogen, hydrogen sulfide, and methane. Sunlight, however, fails to reach the seafloor where deep-sea hydrothermal vents are located.
As part of an investigation, researchers collected living specimens from an area near a deep-sea hydrothermal vent. Mussels in the collection were found to be dependent on molecular hydrogen in seawater. Also, the researchers discovered multiple species of bacteria living in the gills of the mussels. Mussels use gills for filter-feeding and gas exchange with the surrounding seawater. On the basis of their experimental results, the researchers hypothesized that some bacteria living in the gills of the mussels are capable of chemosynthesis.
Which of the following best explains how biological communities near deep-sea hydrothermal vents can exist in a habitat lacking sunlight?
(A) Environmental conditions on some distant planets resemble those experienced by organisms living near hydrothermal vents.
(B) Heterotrophs metabolize carbon-containing compounds produced by the photosynthetic organisms that live on the seafloor.
(C) Some organisms rely on energy captured from inorganic compounds to drive basic biological processes.
(D) Some organisms that can tolerate high temperatures are single celled, whereas others are multicellular.

46. The food web above represents feeding relationships in a biological community near a deep-sea hydrothermal vent. Hydrothermal vents are geysers on the seafloor that gush super-heated, mineral-rich water. The seawater surrounding hydrothermal vents typically contains carbon dioxide , molecular hydrogen, hydrogen sulfide, and methane. Sunlight, however, fails to reach the seafloor where deep-sea hydrothermal vents are located.
As part of an investigation, researchers collected living specimens from an area near a deep-sea hydrothermal vent. Mussels in the collection were found to be dependent on molecular hydrogen in seawater. Also, the researchers discovered multiple species of bacteria living in the gills of the mussels. Mussels use gills for filter-feeding and gas exchange with the surrounding seawater. On the basis of their experimental results, the researchers hypothesized that some bacteria living in the gills of the mussels are capable of chemosynthesis.
On the basis of the food web, which of the following members of a deep-sea biological community is most likely to also have a symbiotic relationship with chemosynthetic organisms?
(A) Octopuses
(B) Blind crabs
(C) Zoarcid fish
(D) Shrimp

48. On the evening of Saturday December 6th 2008 a number of Irish news sources reported that testing had revealed "extremely high" levels of PCBs in pork products, ranging from 80 to 200 times the EU's upper safe limit of 1.5 pg/g i.e to 0.3 parts per billion. The PCB levels involved are small in comparison to other contamination incidents, indeed in 1986 the breast milk of healthy nursing mothers in the US contained between 1020 to 1770 ppb of PCBs and the PCB contaminated rice-bran oil that caused mass poisoning (Yu-Cheng) in Taiwan in 1979 contained between 53,000 to 99,000 ppb of PCBs.
Brendan Smith, the Minister for Agriculture, Fisheries & Food, stated that pork contamination was caused by PCB contaminated feed that was used on 9 out 400 of Ireland's pig farms and only one feed supplier was involved. Smith added that 38 beef farms also used the same contaminated feed, but those farms were quickly isolated and no contaminated beef entered the food chain. While the contamination was limited to just 9 pig farms, the Irish government requested the immediate withdrawal and disposal of all pork-containing products produced in Ireland and purchased since September 1st 2008.

49. Exotic Species

50. A researcher is investigating the relationship between the existing species diversity in a community and the ability of an introduced nonnative species to destabilize the community.
Which of the following graphs is most consistent with the claim that communities with high diversity are more resistant to change than are communities with low diversity? c. a. d. b.

51. The lionfish is a venomous fish found primarily in the Red Sea and the Indian Ocean. In the 1990s, lionfish were accidentally released into the Atlantic Ocean, where they found abundant resources and favorable environmental conditions. Which of the following scenarios is most likely to result in the lionfish having a major impact on the communities into which they were introduced?
(A) With no natural predators, the lionfish population will become very large.
(B) Some native species of invertebrates will develop a resistance to lionfish venom.
(C) Random mating will allow the lionfish population to reach Hardy-Weinberg equilibrium.
(D) A virus that specifically infects lionfish will become more prevalent.

52. In a certain prairie community, a dominant prairie grass species has recently been infected with a virus that
disrupts one of the electron transport proteins in the chloroplasts of infected cells.
Describe the most likely effects on cellular processes
(be specific as to which processes and molecules
are most likely to be directly affected).
(b) Describe and explain the most likely effects on individual infected plants.
(c) Predict the short-term effects (within a year of infection) on the infected plant populations and their communities. Justify your prediction.
(d) Predict the long-term effects (years to decades after infection) on the infected plant populations and their communities. Justify your prediction.

53. Energy Flows!
Matter Cycles!

54. Water cycle

56. How much carbon (in g/m2) is released into the atmosphere as a result of the metabolic activity of herbivores?
Give your answer to the nearest whole number.

58. Figure I shows the growth of an algal species in a flask of sterilized pond water. If phosphate is added as indicated, the growth curve changes as shown in Figure II.
Which of the following is the best prediction of the algal growth if nitrate is added instead of phosphate? a. c. b. d.

67. Prevailing winds drive the major ocean surface currents.
Example: northeast trade winds drive water to the west; when it reaches a continent it is deflected northward until the westerlies drive the water back to the east.

68. Deep ocean currents are driven by water density differences.
Colder, saltier water is more dense and sinks to form deep currents.
Deep currents regain the surface in areas of upwelling, completing a vertical ocean circulation.
Oceans and large lakes moderate climate because water has a high heat capacity.
Water temperature changes slowly as it exchanges heat with the air.
Poleward-flowing ocean currents carry heat from the tropics toward the poles, moderating climate at higher latitudes.
Example: the Gulf Stream warms northern Europe.

69. Topography produces additional environmental
heterogeneity

70. Biomes

71. Tropical Forests

72. The area covered by tropical rain forest is reduced
by millions of hectares per year due to agriculture
and logging. Which of the following best describes a likely result of tropical rain forest deforestation?
(A) Populations of plants and animals will decrease as more rain forest disappears, leading to a decrease in biodiversity.
(B) An increase of soil moisture will lead to a rapid increase in new vegetation coverage.
(C) An increase in atmospheric carbon dioxide will lead to higher levels of ultraviolet radiation reaching the surface of Earth.
(D) More oxygen will be available to other organisms as plant numbers decrease.

73. Savanna

74. Desert

75. Chaparral

76. Temperate Grassland

77. Temperate Forest

78. Tiaga or Boreal Forest
Coniferous Forest

79. Tundra

80. Ponds and Lakes

81. Wetland

82. Streams and Rivers

83. Estuary

85. Coral Reef

87. In the Arctic Ocean, the predominant primary
producers are phytoplankton. Phytoplankton
are consumed by zooplankton, which in turn
areeaten by codfish. In years when there is
moreopen water (less ice coverage), there are
morezooplankton and fish than in years with
less openwater (more ice coverage). Based
on the graphabove, the difference is most
likely because
(A) when there is less open water, light is blocked
from the zooplankton, so they cannot produce as much food for the fish
(B) when there is more open water, the temperature is warmer, so the zooplankton and fish populations increase in size
(C) the ice blocks the light, so in years with more ice coverage, there is less photosynthesis by the phytoplankton
(D) the ice increases the light available for photosynthesis, so primary production increases and zooplankton populations increase in size

88. Benthos