ecology ap biology. ecology scientific study of the interactions between organisms and their...
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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
Population Characteristics
• Dispersal Patterns
• Spacing between individuals
• Clumped• Uniform• Random
Population Characteristics
• Dispersal Patterns
• Clumped
Population Characteristics
• Dispersal Patterns
• Uniform
Population Characteristics
• Dispersal Patterns
• Random (ferns)
Population Characteristics
• 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
Population Characteristics
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
Population Growth Models
• Exponential Growth• J-shaped curve
Population Growth Models
• 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
Population Growth Models
• 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
Community Interactions
• 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
Community Interactions
• Symbiosis• Two species that live together in close
contact• Types
– Mutualism– Commensalism– Parasitism
Community Interactions
• Mutualism• Both species benefit from relationship• Examples
– Bacteria in root nodules– Lichens – algae & fungus living
together
Community Interactions
• Commensalism• One species benefits
while the other is neither harmed nor helped
• Examples– Birds building nests
in trees– Egrets that eat
insects around cattle
Community Interactions
• 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
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