Introduction to Ecology

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Introduction to Ecology

• Chapter 19

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19.1 Ecology

• The study of the interactions between organisms
  and the living nonliving parts of the
  environment
• Humans have always needed to understand
  ecology in order to survive

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Todays Environment

• Early human cultures were Hunter-Gatherers
  (relied on practical knowledge about the
  environment)
• Current human cultures need to
• understand the critical impact they
• have on the Earth (depletion of
• natural resources)

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Human Population

• The human population has steadily increased
• There was a rapid increase after the industrial
  revolution (better hygiene, transportation,
  vaccinations, food harvest and shipment)
• According to the U.N., the world population could
  be between 7.8 12.5 billion by 2050

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Effects of the Human Population

• As the human population continues to grow, we
  increase the demand for Earths resources
• Since all life is interconnected, human
  destruction of habitats and contamination from
  our pollution will have an impact on all living
  organisms

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The Sixth Mass Extinction

• According to fossil records, there have been 5
  mass extinctions in the past
• Currently, we are experiencing the 6th mass
  extinction!
• The overpopulation of humans is causing species
  to become extinct on a daily basis

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Ozone Depletion

• Ozone layer protects living organisms from
  harmful UV radiation
• Chlorofluorocarbons (CFCs) chemically react with
  the ozone and destroy it

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Ozone Depletion

• Although the depletion occurs over most of the
  planet, it is most concentrated over Antarctica
• The ozone hole led to the ban of CFCs in 1992
• Currently, 1 of UV rays reaches
• Earths surface and causes ½ million
• cases of skin cancer each year

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Climatic Changes

• Greenhouse Effect carbon dioxide and water vapor
  in the atmosphere redirect Earths reflected heat
  and keep the planet warm enough to sustain life
• Human activities are continually increasing the
  amount of CO2 in the atmosphere

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Global Warming

• As fossil fuels are burned, CO2 is released
• More people more fossil fuels being used a
  warmer planet
• More CO2 in the atmosphere results in more heat
  being redirected back at our planet

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Impacts of Global Warming

• The average global temperature will increase 3-8º
  F by 2100
• Polar ice caps are already melting faster than
  expected
• Changes in rainfall and weather
• patterns will lead to famine,
• starvation, and disease

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Levels of Organization in Ecology
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The Biosphere

• Where all life is found on Earth
• Extends 8-10 km above Earths surface and below
  the ocean into the deepest parts
• Most organisms are found within a few meters of
  the surface of the land or oceans

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Ecosystems

• Includes all of the organisms (biotic factors)
  and the nonliving components (abiotic factors) in
  a particular place
• Example a pond ecosystem

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Community

• All of the interacting organisms living in an
  area
• Ecologists study how species interact and how
  these interactions influence the entire community

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Population

• All the members of a species that live in the
  same place at the same time

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Organism

• Refers to a living thing
• Ecologists study the adaptations that an organism
  has that helps it overcome the challenges in its
  environment

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Key Theme

• All life is interconnected! No organism is
  isolated!
• Survival of a species (including humans) depends
  on interdependence
• Example humans could not survive without the
  nitrogen-fixing bacteria that live in the roots
  of legume plants

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Disturbances in Ecosystems

• One change in an ecosystem will affect many
  species
• Example logging a forest (results in less
  habitat for all animal species, increases runoff
  that leads to water pollution, less trees using
  the atmospheric CO2 , etc.)

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Ecological Models

• Models are often used when studying ecosystems
• Can be graphs, diagrams, or mathematical equations

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19.2 Ecology of Organisms

• Where an organism lives depends on its
  evolutionary history, its tolerances and
  requirements, the history and conditions of its
  habitat, and many other factors

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Biotic and Abiotic Factors

• Biotic factors- includes the living and once
  living components
• Abiotic factors- nonliving components such as the
  physical and chemical characteristics of the
  environment

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The Changing Environment

• Abiotic factors are always changing (daily
  temperature changes, rainfall, seasons, etc)
• Organisms are adapted to function within a
  specific range of temperatures
• An organism cannot survive in areas
• where the temperatures are beyond its tolerance

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Acclimation

• An organisms adjustment to an abiotic factor
• Occurs within the lifetime of an individual
  (NOT an adaptation!)
• Example goldfish raised at higher temps. will
  have a different tolerance curve

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Control of Internal Conditions

• Conformers organisms that dont regulate their
  internal conditions (example desert lizards)
• Regulators organisms that use energy to control
  some of their internal conditions (example
  mammals)

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Escape from Unsuitable Conditions

• Dormancy a state of reduced activity during
  periods of unfavorable environmental conditions
• Examples hibernation and estivation

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Migration

• Moving to a more favorable habitat to escape
  unfavorable conditions
• Example bird migration

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Resources

• Refers to the energy and materials a species
  needs to survive
• Includes food, nesting sites, territory, water,
  sunlight, optimal temperature range

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The Niche

• A species way of life or its role in the
  environment
• Includes the range of conditions the species can
  tolerate, how it obtains its resources, the
  number of offspring, time of reproduction, etc.

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Fundamental vs. Realized Niche

• Fundamental niche- the entire range of conditions
  and resources that a species could potentially
  utilize (very broad)
• Realized niche- includes what is actually used by
  a species

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Niche Differences

• Generalists species with broad niches (can
  tolerate a range of conditions and use a variety
  of resources) example moths
• Specialists species with narrow niches (feed on
  a limited type of resources) example butterflies