Ecology AP Biology. Ecology Scientific study of the interactions between organisms and their...

Ecology

AP Biology

Ecology

• Scientific study of the interactions between organisms and their environment

Levels of Study

• Organism– Individual– 1 turtle

Levels of Study

• Population• Individuals of

the same species living in the same area

• All the turtles of the same species

Levels of Study

• Community• All the organisms

living in an area• All the turtles,

plants, insects, algae, bacteria

Levels of Study

• Ecosystem• All the organisms

and all the abiotic factors

• All the organisms & the soil, water, gases, minerals

Levels of Study

• Biosphere• All the

organisms & all the abiotic factors on Earth

• Earth

Abiotic Factors

• Nonliving• Temperature• Climate• Soil type• Rainfall• Gases• Minerals

Biotic Factors

• Living• Predators• Parasites• Herbivores• Carnivores• Decomposers

Biomes

• Tropical rainforest• Tall trees• High temperature• Heavy rainfall

Biomes

• Savannas• Tropical• Grasslands• Scattered trees• High temperature• Less rainfall than

tropical rain forest

Biomes

• Temperate grasslands

• Grasses• Seasonal droughts• Occasional fires• Lower temperature &

less rainfall than savannas

Biomes

• Deciduous forests• Deciduous trees• Oak, maple• Warm summers• Cold winters• Moderate rainfall

Biomes

• Taiga• Coniferous forests• Pines & firs• Cold winters• Heavy snowfall

Biomes

• Tundra• Grasses & sedges• Very cold winters• Permafrost• High winds• Little rain

Population Ecology

• Refer to written notes as you go through the slides

Population

• Definition:– Group of individuals:

• Of same species• Living in same area• Using the same resources• Responding to same stimuli

Population Characteristics

• Density• Number of

individuals per unit area or volume


• Dispersal Patterns

• Spacing between individuals

• Clumped• Uniform• Random



• Clumped



• Uniform



• Random (ferns)


• Demographics• Study of vital

statistics• Age structure

– Groupings by age– Graphed

• Sex ratio– % of females

compared to males

Analyze the following graphs

• Determine what is causing the various demographic trends in each country

Survivorship Curves

• Graph of # of survivors vs. relative age

Survivorship Curves

• Type I• Most

survive to middle age

• Humans

Survivorship Curves

• Type II• Likelihood

of death same at any age

• Squirrel

Survivorship Curves

• Type III• Most die

young• Oyster

Limiting Factors – add to notes at bottom of page 2• Prevent population from reaching

biotic potential• Types

– Density dependent– Density independent

Limiting Factors

• Density dependent• Effect becomes more intense with

increased density• Examples

– Parasites & diseases– Competition for resources– Toxic effect of waste products– Predation

Limiting Factors

• Density independent• Occur independently of density• Examples:

– Natural disasters– Climate extremes

Population Growth Models

• Exponential Growth• Change in # of individuals (N) over

time (t) is equal to the growth rate (r) times the number of individuals (N)

rNt

N


• Exponential Growth• J-shaped curve


• Logistic Growth• When limiting factors restrict size of

population to carrying capacity• Carrying capacity (K) = max. # of

individuals of a population that can be sustained by the habitat

K

NKrN

t

N


• Logistic Growth• Sigmoid (S) shaped curve

Life-History Strategies

• r-selected species• Exhibit rapid growth (J-curve)• Examples – grasses, insects• Characterized by opportunistic species

– Quickly invade habitat– Quickly reproduce– Then die

• Produce many offspring that are small, mature quickly, require little parental care

Life-History Strategies

• k-selected species• Population size remains relatively

constant• Example - humans• Produce small number of relatively

large offspring that require extensive parental care

• Reproduction occurs repeatedly during lifetime

Community Ecology

• Defintion– An assemblage of populations

interacting with one another within the same environment

– Use the following slides as reference for question 2

Community Interactions

• Interspecific Competition• Competition between different species• When 2 species compete for same

resources one will be more successful• To survive, the less successful species

– Must use slightly different resources– Must use resources during different

time of day


• Predation• Any animal that totally or partly

consumes a plant or animal• True predator kills and eats another

animal• Parasite lives in and off a host• Herbivore is an animal that eats

plants


• Symbiosis• Two species that live together in close

contact• Types

– Mutualism– Commensalism– Parasitism


• Mutualism• Both species benefit from relationship• Examples

– Bacteria in root nodules– Lichens – algae & fungus living

together


• Commensalism• One species benefits

while the other is neither harmed nor helped

• Examples– Birds building nests

in trees– Egrets that eat

insects around cattle


• Parasitism• One species benefits while the other

is harmed• Examples

– Tapeworm inside animal– Ticks on dog

Ecological Succession

• Def- species replacements in a community following a disturbance

• Primary – occurs in areas where there is no soil formation (volcanic eruption, glacial retreat)

• Secondary – area where soil is present (after a fire, farmland)

• Detroit

Climax Community

• F.E. Clements – succession in a particular area will always yield the same type of community – this community is called the Climax Community

Pioneer species – the first species to begin secondary succession (plants)

Trophic Levels

• Primary producers

• Plants• Photosynthetic

bacteria• Algae

Trophic Levels

• Primary consumers

• Herbivores• Eat producers

Trophic Levels

• Secondary consumers

• Carnivores• Eat primary

consumers (herbivores)

Trophic Levels

• Tertiary consumers

• Secondary carnivores

• Eat secondary consumers

Pyramids

• Pyramid of numbers

• Most = producers• Least = top level

consumers

Pyramids

• Pyramid of energy• Most = producers• Least = top level consumers

Pyramids

• 10% rule• Only 10% of

energy available at each trophic level is converted into new biomass at the next level

Food Chain

Food Web

Nitrogen Cycle

Water Cycle

Carbon Cycle

Human Impact

• Greenhouse effect• Ozone depletion• Acid rain• Deforestation• Pollution• Species extinction

Ecosystems & Human Interferences

Chapter 48

64

Outline

• The Nature of Ecosystems– Biotic Components– Autotrophs– Heterotrophs

• Energy Flow– Ecological Pyramids

• Global Biogeochemical Cycles– Hydrologic Cycle– Carbon Cycle– Nitrogen Cycle– Phosphorus Cycle

65

Nature of Ecosystems• Biosphere is the organism-containing

part of the– Atmosphere– Hydrosphere, and– Lithosphere

• An ecosystem is a place where organisms interact with the physical environment– Ecosystems characterized by:

• Cyclical flow of materials from abiotic environment through biotic community and back

• One-way flow of energy

66

Ecosystems

67

Biotic Components:Autotrophs• Producers are autotrophs

– Require only inorganic nutrients and an outside energy source to produce organic nutrients

– Photoautotrophs– Chemoautrophs

68

Biotic Components:Heterotrophs• Consumers are heterotrophs

• Require a source of preformed organic nutrients

– Herbivores - Feed on plants

– Carnivores - Feed on other animals

– Omnivores - Feed on plants and animals

• Decomposers are also heterotrophs

– Bacteria and fungi

– Break down dead organic matter

69

Biotic Components

70

Energy Flow andChemical Cycling• Nutrients pass one-way through food chain from one

level to another

– Each level retains some energy

– The rest is converted to heat, which dissipates into the environment

• Chemicals cycle as organic nutrients

• Once used, they are returned back to the producers by

– Excretion

– Death

– Cellular Respiration

71

Nature of an Ecosystem

72

Energy Balances

73

Grazing & Detrital Food Webs

74

Ecological Pyramids

• A trophic level• Composed of all the organisms

that feed at the same level in a food chain

• Only about 10% of the energy of one trophic level is useable to the next trophic level– Explains why few top carnivores can

be supported in a food web

75

Ecological Pyramid

76

GlobalBiogeochemical Cycles• Chemical cycling may involve:

– Reservoir - Source normally unavailable to producers• Fossil Fuels• Minerals• Sediments

– Exchange Pool - Source from which organisms generally take chemicals• Atmosphere• Soil • Water

– Biotic Community - Chemicals remain in food chains, perhaps never entering a pool

77

Model for Chemical Cycling

78

Hydrologic Cycle

• Fresh water evaporates from bodies of water

• Precipitation on land enters the ground, surface waters, or aquifers

• Water eventually returns to the oceans

79

The Hydrologic (Water) Cycle

80

Carbon Cycle

• Atmosphere is an exchange pool for carbon dioxide– The total amount of carbon dioxide

in the atmosphere has been increasing every year

– Thought to be due to fossil fuel combustion• Transfer Rate

81

The Carbon Cycle

82

Greenhouse Effect• Greenhouse gases

– Carbon dioxide, nitrous oxide, methane

– Allow sunlight to pass through atmosphere

– Reflect infrared back to earth– Trap heat in atmosphere

• If Earth’s temperature rises– More water will evaporate– More clouds will form, and– Setting up a potential positive

feedback loop

83

Earth’s Radiation Balances

84

Nitrogen Cycle

• Atmospheric nitrogen is fixed by bacteria– Make it available to plants– Nodules on legume roots

• Nitrification - Production of nitrates• Denitrification - Conversion of

nitrate to nitrous oxide and nitrogen gas– Balances nitrogen fixation

85

The Nitrogen Cycle

86

Nitrogen and Air Pollution• Acid Deposition

– Nitrogen oxides and sulfur dioxide are converted to acids when they combine with water vapor

– Acid rain dramatically reduces pH of surface waters in some areas

– Causes heavy metals to leach out of rocks, poisoning aquatic organisms

– Kills plants and causes fish to be unfit for human consumption

• Smog

87

Acid Deposition

88

Thermal Inversion

89

Phosphorus Cycle

• Phosphorus does not enter the atmosphere

– Sedimentary cycle

• Phosphate taken up by producers incorporated into a variety of organic molecules

– Can lead to water eutrophication

• Biomagnification

90

The Phosphorus Cycle

91

Sources of Water Pollution

92

Review

• The Nature of Ecosystems– Biotic Components– Autotrophs– Heterotrophs

• Energy Flow– Ecological Pyramids

• Global Biogeochemical Cycles– Hydrologic Cycle– Carbon Cycle– Nitrogen Cycle– Phosphorus Cycle

Ecosystems & Human Interferences

Ending Slide Chapter 48

Ecology AP Biology. Ecology Scientific study of the interactions between organisms and their...

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