Biology

1
Biology

• Chapter 18
• Introduction to Ecology

2

• 18-1 Intro to Ecology
• 18-2 Ecology of Organisms
• 18-3 Energy Transfer
• 18-4 Ecosystem Recycling

3
18-1 Intro to Ecology Objectives

• Identify a key theme in Ecology.
• Describe an example showing the effects of
  interdependence upon organisms in their
  environment.
• Identify the importance of models to ecology.
• State the five different levels of organization
  at which ecology can be studied.

4
Ecology

• The study of the interactions between organisms
  and the living and nonliving components of their
  environment.
• Organisms depend in some way on other living and
  non-living things in their environment
• Broad science that involves collecting info about
  organisms and their environment, observing and
  measuring interactions, looking for patterns and
  seeking to explain these patterns.

5

• Named in 1866 but has always been important to
  humans
• 10,000 to 12,000 yrs ago ancestors obtain food by
  hunting and gathering. Survival depended on
  practical knowledge about environment.
• Development of agriculture stabilized the food
  supply. Less nomadic way of life.

6
(No Transcript)
7
Interdependence A key theme in Ecology

• Interconnectedness
• Interactions between organisms and their
  environment.

8

• Ex. Plants and other photosynthetic organisms
  produce O2 needed by cells of all organisms to
  release the energy in food. Photosynthetic
  organisms depend on CO2 gas released by cellular
  respiration and geochemical processes (volcanic
  eruptions) to make carbohydrates during
  photosynthesis.

9

• Effects of Interdependence
• Any change in the environment can spread through
  the network of interactions and affect organisms
  that appear far removed from the change.
• Example Forest ecosystem in Eastern U.S. Fig
  18-1 p360 Acorn production is connected to spread
  of Lyme disease. High acorn production ? more
  deer and mice ? more ticks ? more Lyme disease.

10
Ecological Models

• A physical, conceptual, or mathematical
  representation used to describe an ecological
  system.

11

• Used to help understand environmental
  interactions and make predictions about possible
  changes. Predictions can be tested by comparing
  them with observations from the natural world.

12

• Used to plan and evaluate solutions to
  environmental problems.

13

• May be limited in application. Cannot always
  account for influence of every variable in real
  environment.

14
Levels of Organization

• Hierarchy within organisms organ system ? Organ
  ? Tissue ? Cell ? Organelles
• Levels in the Environment Fig 18-2 p361
• Each level has unique properties that result from
  interactions
• Ecologist often focus on one level

15
(No Transcript)
16
Biosphere

• Thin volume of earth and its atmosphere that
  support life
• 20km thick (18 miles). 8 to 10 km above earths
  surface (5-6 miles) to deepest part of the ocean
• Earths diameter is 12, 700km (7,900 miles) or
  more than 600x thicker (apples skin like the
  biosphere)
• The film of life covering an otherwise lifeless
  planet.
• Living things are not distributed evenly. Most
  are found within a few meters of the surface.

17
Ecosystem

• Includes all of the organisms and non-living
  environment found in a particular place.
• Example pond ecosystem, forest ecosystem

18
Community

• All the interacting organisms living in an area

Florida mangroves and white egrets
19
Population

• Includes all the members of a single species that
  live in one place at one time

Bighorn Sheep Population
20
Organism

• An individual.
• Study adaptations that allow organism to overcome
  changes of the environment.

21
(No Transcript)
22
18-2 Ecology of Organisms Objectives

• Compare abiotic factors with biotic factors and
  list two examples of each.
• Describe two mechanisms that allow organisms to
  survive in a changing environment.
• Explain the concept of the niche.

23
Habitat

• The place where an organism lives

Salt Marsh Habitat
Woodland Habitat
24
Marine Habitat
Desert Habitat
Intertidal Habitat
Grassland Habitat
25
Ecosystem Components

• Biotic factors
• living components of the environment.
• Ex. Size of a population, pollination by insects

26

• Abiotic factors
• Non-living physical or chemical characteristics
  of the environment.
• Not constant.
• Ex. Temperature, salinity, O2 concentration,
  amount of sunlight, nitrogen, or precipitation.
• Importance varies from environment to environment

27

• Abiotic and biotic factors are not independent.
  Organisms change their environment and are
  influenced by those changes.
• Ex. Availability of nitrogen affects how fast
  plants grow and use up the nitrogen in the soil.

28
Organisms in a Changing Environment

• Each organism is able to survive within a limited
  range of environmental conditions.
• Tolerance Curve a graph of performance versus
  values of an environmental variable.

29

• Ex. Fig 18-5 p464
• An organisms range may be determined by the
  levels of one or more factors.

30

• Acclimation
• When organisms adjust their tolerance to abiotic
  factors
• Occurs within the lifetime of an individual
  organism.

• Example If you move to high elevation you
  acclimate to reduced O2 levels or thin air by
  increasing the number of red blood cells and
  increasing the amount of O2 your body can carry

Cactus Wren Daily behavior reflects the
temperature of the microhabitats used. The
orientation of the nest changes during the
breeding season in order to maximize cooling in
this desert environment.
31

• Adaptation
• Genetic change in a species or population that
  occurs from generation to generation over time.

32
Control of Internal Conditions

• Ways organisms deal with changes in their
  environment
• Conformers do not regulate their internal
  conditions. Change as the internal environment
  changes. Internal conditions remain within
  optimal range as long as external does.

This Iguana is common in the canopies of
Neotropical forests. It controls its body
temperature and activity state by behaviorally
varying its exposure to sunny and shady regions
in the canopy.
33

• Regulators Use energy to control some of their
  internal conditions. Keep internal conditions
  within optimal range over a wide variety of
  external conditions.

Ex. Human body temp 37C (98.6F) Ex. Pacific
Salmon live part of life in salt water and part
in fresh but are able to regulate their internal
salt concentrations
34
Birds fluff up feathers in cold. Change color
with seasons
Cools body by circulating blood through ears
Counter current heat exchange
35
(No Transcript)
36
(No Transcript)
37
Escape from Unstable Conditions

• Hide underground or in shade during hot part of
  day.
• Become nocturnal

Scorpion active at night
38

• Dormancy longer term strategy. Enter state of
  reduced activity during winter or drought.
  Example Reptiles and amphibians hide underground
  during winter

Bats and Polar bears hibernate in winter
39
(No Transcript)
40

• Migration move to a more favorable habitat. Ex.
  Seasonal movement of birds

41
Niche

• Specific role or way of life of a species within
  its environment. Includes range of conditions
  species tolerates, resources used, method to
  obtain resources, number of offspring, time of
  reproduction, etc.

• Some species occupy more than one niche within a
  lifetime. Ex. Caterpillar ? butterfly

42
Generalist

• Species with broad niche.
• Tolerate range of conditions and variety of
  resources.
• Ex. Virginia Opossum eats eggs, dead animal,
  fruits, plants

43
Specialist

• Narrow niches.
• Ex. Koala only eats a few species of eucalyptus

Panda only eats bamboo
44
(No Transcript)
45
(No Transcript)
46
18-3 Energy Transfer Objectives

• Summarize the role of producers in an ecosystem.
• Identify several kinds of consumers in an
  ecosystem.
• Explain the important role of decomposers in an
  ecosystem.
• Compare the concept of a food chain with that of
  a food web.
• Explain why ecosystems usually contain only a few
  tropic levels.

47

• All organisms need energy to carry out essential
  functions (growth, movement, maintenance, repair,
  reproduction)
• Energy flow affects the ecosystems structure.
• sun? autotrophs ? heterotrophs

48
Producers

• Make organic molecules (food)
• Autotrophs make own food.
• Ex. Terrestrial plants Aquatic some protists,
  some bacteria

49
Algae are photosynthetic organisms that occur in
most habitats. They vary from small,
single-celled forms to complex multicellular
forms, such as the giant kelps that grow to 65
meters in length.. The US Algal Collection is
represented by almost 300,000 accessioned and
inventoried herbarium specimens.
50

• Most are photosynthetic (solar energy), some are
  chemosynthetic (energy in inorganic molecules)

51
Gross Primary Productivity

• Rate at which producers in an ecosystem capture
  the energy of sunlight by producing organic
  compounds.
• Producer uses energy and CO2 ? makes sugar ? used
  for cell resp. to provide energy for maintenance,
  repair, growth, reproduction, etc.

52

• Biomass organic material produced in an
  ecosystem
• Producers add biomass to an ecosystem
• Only energy stored as biomass is available to
  other organisms

53
Net Primary Productivity

• The rate at which biomass accumulates.
• Typically expressed in
• units of energy per unit area per year. kcal/m2/y
  
• Units of dry organic mass per unit are per year.
  g/m2/y
• NPP GPP Rate of resp. in producers

54

• Fig 18-7 NPP can vary greatly between ecosystem.
• Tropical rainforests 25x greater than deserts.
• Tropical rainforest id 5 of earths surface but
  30 of world NPP
• Terrestrial variations occur due to light, temp.,
  precipitation
• Aquatic variations due to light and availability
  of nutrients.

55
Consumers

• All animals, most protists, all fungi, many
  bacteria
• Cannot make own food. Eat other organisms or
  organic wastes.
• Heterotrophs

56

• Herbivores eat producers. Ex. Antelope
• Carnivores eat other consumers Ex. Lion, cobra,
  praying mantis
• Omnivores eat autotrophs and heterotrophs
  (producers and consumers) Ex. Grizzly bear

57

• Detritivores consumers that feed on garbage of
  an ecosystem
• Detritus waste dead organisms, fallen leaves,
  animal wastes
• Ex. Vulture, many bacteria, and fungi

termites
58

• Decomposers detritivores that cause decay by
  breaking down complex molecules into simpler
  molecules. Make nutrients that were contained in
  detritus available to autotrophs. Recycle
  chemical nutrients

59
Energy Flow

• When one organism eats another organism,
  molecules are metabolized and energy is
  transferred. Energy flows through an ecosystem.

• Trophic Level indicates the organisms position
  in a sequence of energy transfers.
• 1st producers
• 2nd herbivores
• 3rd predators
• Most ecosystems have 3 or 4 levels. Marine
  ecosystems may have more.

60

• Food chain single pathway of feeding
  relationships among organisms in an ecosystem.
• Ex. Fig 18-9 grass ? mouse ? snake ? hawk
• Arrow represents energy flow

61

• Food Web interrelated food chains. Ex. Fig 18-10

62

• Energy transfer Fig 18-11. Amount of energy
  stored as organic material in each trophic level
  in ecosystem.
• Pyramid shaped because only about 10 of energy
  transferred to next level.

63

• Low because
• Some organisms escape being eaten, may die and
  decompose but dont pass energy to next level.
• When being eaten, some molecules are in a form
  that cannot be broken down by consumers (hair,
  horns, hooves)
• Use energy to live before being eaten
• No transfer of energy is 100 efficient. Some
  energy is lost as heat to the environment.

64

• Limitations of Trophic Levels
• Low rate of energy transfer ? fewer trophic
  levels. Not enough energy remaining in top levels
  to support organisms
• Organisms in low levels are more abundant than in
  higher levels. Ex. 1000 zebras or gazelle per
  lion or leopard and far more grass and shrubs.

65
18-4 Ecosystem Recycling Objectives

• List four major biogeochemical cycles.
• Summarize 3 important processes in the water
  cycle.
• Outline the major steps in the carbon cycle.
• Describe the role of decomposers in the nitrogen
  cycle.
• Summarize the major steps of the phosphorus cycle.

66

• As energy and matter flow through an ecosystem,
  matter must be recycled and reused.
• Biogeochemical Cycles pass substances between
  living and non-living parts of an ecosystem. Ex.
  Water, carbon, nitrogen, calcium, phosphorus

67
Water Cycle

• Water Cycle the movement of water between
  reservoirs. Fig 18-12 p371

• Crucial to life.
• 70-90 of a cell is water.
• Environment for chemical reactions
• Key factor that regulates the productivity of
  terrestrial ecosystems.

68

• Water reservoirs
• Very little of the available water on earth is
  trapped within living things at any given time.
• Bodies of water lakes, rivers, streams, oceans
• Atmosphere water vapor
• Ground water in soil or underground formations
  of porous rock

69
(No Transcript)
70

• 3 important processes
• Evaporation heat causes water to evaporate from
  bodies of water, soil, living things and change
  to water vapor in the atmosphere.
• Transpiration the process by which water
  evaporates from the leaves of plants
• Precipitation the amount of water the atmosphere
  can hold depends on abiotic factors such as temp.
  or air pressure. Once the atmosphere becomes
  saturated precipitation occurs. (rain, snow,
  sleet, hail. fog)
• Plants absorb water from soil through plant
  roots.
• Animals drink water and release it when they
  breathe, sweat, or excrete.

71
Carbon Cycle

• Fig 18-13
• Short-term Carbon Cycle
• Photosynthesis plants/autotrophs use CO2 and H2O
  and sunlight to make carbohydrates.
• Cellular Respiration autotrophs and heterotrophs
  us O2 to break down carbohydrates. Byproducts are
  CO2 and H2O
• Decomposers release CO2 into atmosphere when
  they break down organic compounds

72
(No Transcript)
73
(No Transcript)
74

• Human Influences -In last 150 years the CO2 has
  risen more than 30 due to
• Burning fossil fuels (coal, oil, natural gas) and
  other organic matter for fuels
• Fossil fuels the remains of organisms that have
  been transformed by decay, heat, and pressure
  into energy-rich molecules. Burning them releases
  energy and CO2
• Large areas of forest are burned each year to
  clear land for agriculture
• Less vegetation remains to absorb CO2 from the
  atmosphere through photosynthesis

75
Nitrogen Cycle

• Complex pathway that nitrogen follows in an
  ecosystem. Fig 18-14 p373
• Needed by organisms to make proteins and nucleic
  acids
• N2 (nitrogen gas) comprises 78 of the atmosphere
• Most plants can use nitrogen only in the form of
  nitrate

76
(No Transcript)
77

• Nitrogen Fixation the process of converting N2
  gas to nitrate
• Nitrogen-fixing bacteria transform N2 into a
  usable form. Live in soil and inside swellings on
  roots of legumes (beans, clover, alfalfa)
• Plants supply carbs (food) for bacteria in return
  for bacteria producing usable nitrogen. Extra
  nitrogen is released into the soil.

78

• Decomposers break down nitrogen containing
  materials in dead organisms (proteins and nucleic
  acids), urine, and dung and release the nitrogen
  as ammonia NH3
• Ammonification NH3 becomes NH4 ammonium in the
  soil
• Nitrification soil bacteria take up ammonia and
  oxidize it into nitrites NO2- and nitrates NO3-
• Erosion of nitrate-rich rocks also releases
  nitrates into an ecosystem.

79

• Plants use nitrates in soil to form amino acids
• Denitrification Nitrogen is returned to the
  atmosphere. Anaerobic bacteria break down
  nitrates and release nitrogen gas into the
  atmosphere
• Animals obtain nitrogen by eating plants and
  other organisms and digesting the proteins and
  nucleic acids.

80
(No Transcript)
81
(No Transcript)
82
(No Transcript)
83
Phosphorus Cycle

• Movement of phosphorus from environment to
  organisms and back to environment. Cycle is slow
  and does not normally occur in the atmosphere
  since phosphorus is rarely a gas.
• Phosphorus element. Essential material needed by
  animals to form bones, teeth, and parts of DNA
  and RNA
• Plants absorb phosphorus from soil and water
  through their roots. Animals get phosphorus by
  eating plants or other animals

84

• When rocks erode, small amounts of phosphorus
  dissolve as phosphate (PO43-) in soil and water.
• Phosphorus is added to soil and water by excess
  phosphorus excreted in wastes from organisms or
  when dead organisms decompose.
• Some phosphorus is applied to fields as
  fertilizer. May erode off land into streams and
  groundwater.

85
(No Transcript)
86
(No Transcript)
87
(No Transcript)