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Ecology
The scientific study of the interactions among organisms and between organisms and their
environments is called ecology. Ecologists, scientists who conduct research in ecology, test their
hypotheses outdoors in the field as well as in the laboratory. Ecologists also use computer models
to understand these complex interactions. Understanding ecology helps people make decisions
about environmental issues, such as how best to manage forests, rivers, and other natural
resources. An organism's environment consists of other organisms as well as nonliving factors.
The prokaryotes, protists, animals, fungi, and plants in the environment are called biotic factors.
The nonliving physical and chemical conditions are called abiotic factors. Ecologists study the
relationships among biotic and abiotic factors at five increasingly broad levels: organisms,
populations, communities, ecosystems, and the biosphere
1. What is ecology?
2. Why do people study ecology
3. What is the difference between biotic and abiotic factors?
Levels of Ecological Study The smallest unit of ecological study is the individual organism.
A blue sweetlip fish is one example of an organism in a coral reef environment. A population is a
group of individual organisms of the same species living in a particular area. A group of sweetlip
fish in the reef environment is an example of a population. The coral reef is home to a collection
of living things including fish, coral animals, microscopic algae, and all other organisms living in
and around the reef. All of the organisms inhabiting a particular area make up a community. An
ecosystem includes the abiotic factors and the biotic factors in an area. A coral reef ecosystem
includes the reef's many species and its nonliving conditions, such as the water temperature and
amount of sunlight. The broadest level of ecological study is the biosphere. The biosphere is
Earth's thin, life supporting layer of air, soil and water. The biosphere extends to an altitude of
several kilometers; the land to a depth of about 2 kilometers; lakes and streams; and the oceans to
a depth of several kilometers. Energy enters the biosphere as solar radiation and exits in the form
of heat.
4. List the five levels of ecological study in order from largest to smallest.
5. How does a population differ from a community?
6. How do a community and an ecosystem differ?
7. Explain why it is more accurate to define the biosphere as the global ecosystem than as the
global community
Patchiness of the Biosphere
The biosphere is not spread out uniformly around the planet. Looking at Earth from a space
shuttle, you would see that the biosphere is "patchy"—like a quilt of different environments,
including land and oceans, lakes and ice. Zoom in closer to observe just one continent, and you
would see an uneven distribution of ecosystems such as deserts, grasslands, forests, and rivers. A
still smaller area, such as a wilderness, may contain patches of woods, fresh water, and marshes.
All these environmental variations are due mainly to differences in abiotic factors such as
temperature, soil type, and the availability of water and light. This patchiness creates a number of
different habitats, or specific environments in which organisms live. Each habitat has
characteristic abiotic and biotic factors. For example, a wilderness may include several habitats:
patches of forest, marshy areas, and a river. The forest patches are home to trees and certain
species of birds and animals. The marshy land areas provide a habitat for many species of
prokaryotes, fungi, and insects that live in and on top of the wet soil. And within the river habitat
is a surface "microhabitat" that supports floating plankton and swimming animals, while the
deeper water is a separate microhabitat, with different light and temperature conditions and a
different community of organisms. An animal’s niche is its way of life it pursues within its
habitat. When it reproduces, the number of offspring, its predators, its prey all are parts of an
animal’s niche.
8. Describe what is meant by the "patchiness" of the environment.
9. What is the difference between an organism’s habitat and an organism’s niche
Key Abiotic Factors.
The sun provides light and warmth and is the energy source for almost all ecosystems on Earth.
Sunlight powers photosynthesis by plants, the main producers in most terrestrial (land)
ecosystems.. In aquatic (water) environments, sunlight provides energy for photosynthetic
producers such as algae. The fact that sunlight only penetrates a short distance into a body of
water affects where algae live within a lake or ocean. Water is essential to all life on Earth. All
organisms contain water—in fact, you consist of nearly 70 percent water! Among its many
important properties, water can dissolve gases such as oxygen and solutes such as salt. Terrestrial
organisms have adaptations that keep them from losing too much water and drying out. For
example, some plants such as pine trees have needle-shaped leaves with a waxy coating. These
leaves minimize the amount of water that evaporates into the air. Aquatic organisms also must
balance their water uptake and water loss. Otherwise, their cells may burst or shrivel due to
osmosis. Most life exists within a fairly narrow range of temperatures, from about 0°C to about
50°C. Few organisms can maintain an active metabolism below 0°C for long, and most
organisms' enzymes are denatured (they lose their shape and stop working) above 50°C.
However, extraordinary adaptations enable certain species to live at extreme temperatures. Some
species of prokaryotes, for example, can thrive in hot springs as hot as 80°C and around deep-sea
vents, which are even hotter. Soil is the product of abiotic forces (such as ice, rain, and wind) and
the actions of living things (such as microorganisms, plants, and earthworms) on the rocks and
minerals of Earth's crust. The structure and chemical makeup of soil greatly affect which
organisms can grow there. Wind can affect the distribution and the activities of organisms in
several ways. Wind moves clouds and rain over Earth's surface. Wind also stirs up water in
ponds, lakes, and streams, creating currents that in turn bring up nutrients from the bottom. Many
land plants depend on wind to help disperse their pollen and seeds.
10. List five abiotic factors and describe how each could influence a living thing..