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Ecology

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Ecology GHSGT REVIEW What is Ecology? The scientific study of: Interactions among organisms Interactions between organisms and their environment Biosphere ... – PowerPoint PPT presentation

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Title: Ecology


1
Ecology
  • GHSGT REVIEW

2
What is Ecology?
  • The scientific study of
  • Interactions among organisms
  • Interactions between organisms and their
    environment
  • Biosphere portions of the Earth where life
    exists (land, water, and air)

3
Levels of Organization
  • Species group of organisms that can breed and
    produce fertile offspring
  • Population a group of individuals of the same
    species that live in the same area
  • Community different populations that live in
    the same area
  • Ecosystem all the organisms plus the nonliving
    environment
  • Biome group of ecosystems with the same climate
    and similar communities

4
Levels of Organization
5
Energy Flow
  • Sunlight is the main energy source for life on
    Earth.
  • Autotrophs (producers) organisms that make
    their own food
  • Photosynthesis use light energy to make food
  • Chemosynthesis use chemical energy to make food

6
Energy Flow
  • Heterotrophs (consumers) organisms that must
    feed on other organisms for energy
  • Herbivores eat only plants
  • Carnivores eat other animals
  • Omnivores eat both plants and animals
  • Detrivores feed on dead matter
  • Decomposers break down organic matter

7
Feeding Relationships
  • Energy flows through an ecosystem in one
    direction (sun ? producers ? consumers)
  • Food chain a series of steps in which organisms
    transfer energy by eating and being eaten

8
Feeding Relationships
  • Food web a network of complex feeding
    interactions
  • Trophic levels each step in a food chain or
    food web
  • 1st producers
  • 2nd primary consumers
  • 3rd secondary consumers
  • 4th tertiary consumers

9
Ecological Pyramids
  • Energy Pyramid shows the amount of energy
    available at each trophic level
  • Only about 10 of the energy is transferred to
    the next level
  • Biomass Pyramid shows the amount of living
    tissue within each trophic level
  • Pyramid of numbers shows the number of
    organisms at each trophic level

10
Ecological Pyramids
11
Biotic and Abiotic Factors
  • Biotic factors the living things that influence
    organisms
  • Abiotic factors the nonliving things that
    influence organisms
  • Light
  • Soil
  • Wind
  • Water
  • Temperature

12
Habitat and Niche
  • Habitat the area where an organism lives
  • Niche the role an organism plays in its habitat
  • No two species can share the same niche in the
    same habitat

13
Community Interactions
  • Symbiosis any relationship in which two species
    live closely together
  • Mutualism both species benefit (flowers
    insects)
  • Commensalism one species benefits while the
    other is neither helped nor harmed (orchids in a
    rainforest)
  • Parasitism one organism benefits while the
    other is harmed (fleas on a dog)

14
Symbiosis
15
Populations
  • Population density the number of individuals
    per unit area
  • Population growth increase in size of a
    population
  • Population size can be affected by
  • Number of births
  • Number of deaths
  • Immigration organisms moving into an area
  • Emigration organisms moving out of an area

16
Exponential Growth
  • Under ideal conditions with unlimited resources,
    a population will grow exponentially
  • J-shaped curve

17
Logistic Growth
  • As resources become less available, the growth of
    a population slows or stops
  • S-shaped curve

18
Limiting Factors
  • A factor that causes population growth to
    decrease
  • The population size will usually remain constant
  • Creates the s-shaped curve
  • Two kinds of limiting factors
  • Density-dependent
  • Density-independent

19
Density-Dependent Factors
  • A limiting factor that depends on population size
  • Competition organisms compete for resources
  • Between members of the same species
  • Between members of different species
  • Parasitism and disease

20
Density-Dependent Factors
  • Predation when one species feeds on another
  • Predator the organism that feeds on the prey
  • Prey the organism being eaten

21
Density-Independent Factors
  • Affects all populations, regardless of the
    population size
  • Unusual weather heavy storms
  • Natural disasters tornado, volcanic eruption
  • Seasonal cycles insects die during winter
  • Human activities clear-cutting forests

22
Evolution of Populations
  • Directional selection - form of natural selection
    in which the entire curve moves occurs when
    individuals at one end of a distribution curve
    have higher fitness than individuals in the
    middle or at the other end of the curve

23
Evolution of Populations
  • Stabilizing selection - form of natural selection
    by which the center of the curve remains in its
    current position occurs when individuals near
    the center of a distribution curve have higher
    fitness than individuals at either end

24
Evolution of Populations
  • Disruptive selection - form of natural selection
    in which a single curve splits into two occurs
    when individuals at the upper and lower ends of a
    distribution curve have higher fitness than
    individuals near the middle

25
Human Population Growth
  • At first the human population grew slowly
  • About 500 years ago it started increasing rapidly
  • Resembles the J-shaped curve

US World Populations
26
Ecological Succession
  • The series of changes that occurs in a community
    over time
  • Primary succession occurs on surfaces where no
    soil exists (no previous life)
  • Pioneer species the first species to populate
    the area
  • Lichens ? mosses ? grasses ? shrubs ? trees

27
Primary Succession
28
Ecological Succession
  • Secondary Succession when a disturbance changes
    the existing community without removing the soil
  • Tornadoes, fire, clear cutting
  • Occurs much quicker than primary succession
  • Climax community the relatively stable final
    community
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