CHAPTER 50 INTRODUCTION TO ECOLOGY

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CHAPTER 50INTRODUCTION TO ECOLOGY
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The Scope of Ecology

• Define ecology. Identify the two features of
  organisms studied by ecologists.
• Describe the relationship between ecology and
  evolutionary biology.
• Distinguish between abiotic and biotic components
  of the environment.
• Distinguish among organismal ecology, population
  ecology, community ecology, ecosystem ecology,
  and landscape ecology.
• Clarify the difference between ecology and
  environmentalism.   

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Interactions Between Organisms and the
Environment Affect the Distribution of Species

• Define biogeography.
• Describe the questions that might be asked in a
  study addressing the limits of the geographic
  distribution of a particular species.
• Describe the problems caused by introduced
  species and illustrate with a specific example.
• Explain how habitat selection may limit
  distribution of a species within its range of
  suitable habitats.
• Describe, with examples, how biotic and abiotic
  factors may affect the distribution of organisms.
• List the four abiotic factors that are the most
  important components of climate.
• Distinguish between macroclimate and microclimate
  patterns.
• Provide an example of a microclimate.
• Explain, with examples, how a body of water and a
  mountain range might affect regional climatic
  conditions.
• Describe how an ecologist might predict the
  effect of global warming on distribution of a
  tree species.
• Name three ways in which marine biomes affect the
  biosphere.

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ECOLOGY SCIENTIFIC STUDY OF INTERACTIONS
BETWEEN ORGANISMS AND THEIR ENVIRONMENT

• Scientific Observations and experiments to test
  hypothetical explanations of ecological phenomena
  multidisciplinary
• Environment Includes biotic and abiotic factors
• Biotic All organisms within an individuals
  environment
• Abiotic Non-living factors light,
  temperature, nutrients, etc
• Interactions between organisms and their
  environments involve how the environment affects
  an organism and how an organisms can change the
  environment

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• BASIC ECOLOGY PROVIDES A SCIENTIFIC CONTEXT FOR
  EVALUATING ENVIRONMENTAL ISSUES

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Factors Affecting Distribution of Organisms

• Biogeography The study of past and present
  distributions of species

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Biogeographic realms regions of distinct plants
and animal species. There is some overlap.
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B. Species Dispersal

• Aids in geographic isolation (in evolutionary
  terms)
• Species transplants
• Introduction of exotic species

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FOUR COMPREHENSIVE LEVELS OF INQUIRY

• Organismal ecology Behavioral, physiological,
  and morphological ways individuals meet abiotic
  environmental challenges
• Distribution tolerance of abiotic factors
• Population ecology Groups of individuals of the
  same species in a particular geographical area
• Population size and composition
• Community ecology All organisms that inhabit a
  particular area
• Predation, competition, etc.
• Ecosystem ecology All abiotic factors and
  communities
• Energy flow, chemical cycling among biotic and
  abiotic components

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ECOLOGY AND EVOLUTION

• Short term interactions of organisms with their
  environments have long term effects through
  natural selection. Ecological time translates
  into effects over evolutionary time

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ABIOTIC FACTORS DETERMINE BIOSHERES DISTRIBUTION
OF ORGANISMS

• Biosphere Portion of Earth inhabited by life
• Biomes Major types of communities and
  ecosystems typical of broad geographical areas

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Important Abiotic Factors

• Environmental Temperature Organisms function
  best within the environmental temperature range
  to which they are adapted
• Water Essential to water balance and conversion
• Sunlight Provides energy that drives nearly all
  ecosystems
• Wind Amplifies effects of temperature by
  increasing heat loss by evaporation and
  convection
• Rocks and soil Physical structure, pH, mineral
  composition limit plant distribution
• Periodic disturbances fires, hurricanes,
  typhoons, volcanic eruptions devastate biological
  communities

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Climate and Distribution of Organisms

• Climate Prevailing weather conditions
• Temperature, water, light, wind
• Climatograph Plots temperature and rainfall in
  a particular region
• Annual means
• Overlap due to other abiotic factors also playing
  a role in biome location

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Current and predicted range for American Beech
tree under 2 climate range scenarios
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Global Climate Patterns

• Latitudinal Variation Light intensity
• Tropics (23.5 degrees N to S) receive direct
  sunlight year round and small seasonal variation
• Seasonal Variation in light, temperature increase
  steadily toward poles

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• Global circulation of air which creates
  precipitation and winds results from intense
  solar radiation near equator
• Earths predictable wind patterns established by
  air flowing in circulation cells. Rotation of
  Earth deflects winds from a vertical path as land
  at equator moves faster than at the poles
• Equator East to west
• Temperate West to east

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• Mountains
• Air temperature declines 6 degrees C for each
  1000m increase in elevation
• Rainfall windward deserts leeward

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• Seasonal Changes
• Upwelling in ocean currents
• Biannual mixing of nutrients in lakes

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COSTS AND BENEFITS OF HOMEOSTASIS

• Regulators and Conformers
• Regulator Maintain homeostasis through
  behavioral and physiological mechanisms
• Conformers Allow internal conditions to vary
  with external conditions
• Energy cost of regulation cannot exceed benefits
  of homeostasis

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Principle of Allocation

• Each organism has a limited amount of energy that
  can be allocated for obtaining nutrients,
  escaping predators, coping with environmental
  fluctuations, growth, reproduction
• Energy expended for one function reduces amount
  of energy available for other functions
• Large expenditure for homeostasis reduces energy
  available for other functions
• Conformers in stable environment more energy
  available for growth/reproduction, but geographic
  distribution restricted
• Regulators Expend energy to survive
  environmental fluctuations grow and reproduce
  less efficiently survive over wider geographic
  range

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ORGANISM RESPONSE MECHANISM

• Behavioral Responses Unfavorable environmental
  changes ? movement from one place to another,
  cooperative social behavior
• Physiological Responses Blood vessel
  constriction, dilation, high altitude blood cell
  production, etc.
• Acclimation Physiological changes that shift
  tolerance limits

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• Morphological Responses Alter body form or
  internal anatomy
• Reversible
• Fur color, density
• Irreversible
• Arrowleaf plant lacks a waxy leaf cuticle
• Adaptation Over Evolutionary Time Responses to
  environmental change have evolved over
  evolutionary time to current levels through
  natural selection

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• GEOGRAPHICAL DISTRIBUTION OF TERRESTRIAL BIOMES
  BASED MAINLY ON REGIONAL VARIATIONS IN CLIMATE
• Ecotone Transitional area between two
  communities

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• Tropical Forest Temperature varies little,
  daylight consistent, rainfall variable
• Lowlands prolonged dry seasons tropical dry
  forests
• Distinct wet and dry seasons, tropical deciduous
  forest
• Tropical rain forest rainfall abundant, great
  diversity, five layers, poor soil due to rapid
  nutrient recycling

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• Savannas Ecotones where forest and grasslands
  meet

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• Desert Low and unpredictable precipitation
• Between 15-30 degrees latitude
• Descending air absorbs moisture
• Plants/animals must have physiological and/or
  behavioral adaptations to conserve water

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• Chaparral Regions of dense, spiny shrubs with
  tough evergreen leaves found along coasts where
  cool ocean current circulate offshore resulting
  in mild, rainy winters and long, hot dry summers
• Found between 3-40 degrees latitude
• Low nutrient soils, aridity, short growing
  seasons, frequent fires

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• Temperate Grasslands Some characteristics of
  tropical savannas but occur in regions with
  relatively cold winters, rich soil

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• Temperate Deciduous Forest Mid-latitude regions
  with sufficient moisture to support growth of
  large, broad leaved deciduous trees
• Several layers of vegetation
• High plant diversity
• soil rich in nutrients

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• Taiga Harsh winters and short, wet summers
  (coniferous forest)
• Precipitation mostly in form of insulating snow
• Soil thin, acidic and forms slowly

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• Tundra Northern-most limits of plant growth and
  limited to low shrubbery or mat like vegetation
• Arctic tundra encircles North Pole and extends
  southward to taiga
• Permafrost
• Little precipitation and evaporation
• Alpine tundra occurs at high elevations in all
  latitudes, altitudes above tree ring
• Low diversity of animal species

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AQUATIC ECOSYSTEMS

• Ponds and Lakes
• Photic zone upper layer where light is
  sufficient for photosynthesis
• Aphotic zone No light, no photosynthesis
• Temperature stratification
• Thermocline Narrow, vertical zone between
  warmer and colder waters where a rapid
  temperature change occurs

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• Stratification of plants and animals
• Littoral zone Shallow, well-lit, close to shore
  with diverse flora and fauna
• Limnetic zone Open, well-lit waters away from
  shore with plankton, fish, snakes, turtles, birds
• Profundal zone Deep, aphotic zone
• Detritus broken down
• Cold, low oxygen
• Nutrient plentiful
• Oligotrophic lakes Deep, nutrient poor,
  phytoplankton not productive
• Eutrophic lakes Shallow, nutrient-rich, with
  productive phytoplankton,
• Human activities increase N and P in lakes
  causing algal blooms

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• Streams and Rivers Bodies of water that move
  continuously in one direction
• Change in structure from head waters to mouths
• Current prohibits plankton attaches algae and
  rooted plants
• Organic material washed from land, important food
  source
• Upstream high oxygen content, different fish
  and insects
• Mouth low oxygen content, different fish and
  insects
• Human activities Channels, dams, pollutants

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• Wetlands An area covered by water that supports
  aquatic vegetation
• Diverse invertebrates, birds
• Improve water quality by filtering pollutants
• Estuary An area where freshwater or river
  merges with ocean
• Diverse flora and fauna
• Salinity varies

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Marine Zone

• Intertidal zone Shallow, terrestrial meets
  ocean water
• Neritic zone Extends from intertidal zone,
  across shallow regions to edge of continental
  shelf
• Coral Reefs
• Oceanic zone Extends over deep water from one
  continental shelf to another
• Pelagic zone Open waters of any depth
• Benthic zone Sea floor

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