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)

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

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 Ecosyste ms

67 Biotic Components: Autotrophs Producers are autotrophs –R–Require only inorganic nutrients and an outside energy source to produce organic nutrients –P–Photoautotrophs –C–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 and Chemical 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 Global Biogeochemical 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 –N–Nitrogen oxides and sulfur dioxide are converted to acids when they combine with water vapor –A–Acid rain dramatically reduces pH of surface waters in some areas –C–Causes heavy metals to leach out of rocks, poisoning aquatic organisms –K–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