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1. An Introduction to Ecology

2. Ecology from Greek: οἶκος, "house"; Lagos, "study of“.
The study of the interactions of living things with each other and
their physical environment.

3. Ecology addresses the full scale of life, from tiny bacteria to processes that
span the entire planet. Ecologists study many diverse and complex relations
among species, such as predation and pollination. The diversity of life is
organized into different habitats, from terrestrial to aquatic ecosystems

4. Ecological Organization:

5. 1. Population: all the members of a species inhabiting a given location
2. Community: all the interacting populations in a given area
3. Ecosystem: the living community and the physical environment functioning together
as an independent and relatively stable system4. Biosphere: that portion of the earth where life exists
a. The biosphere is composed of numerous complex ecosystems.
b. An ecosystem involves interactions between abiotic (physical) and biotic (living)
factors. The members of the community in the ecosystem and environment must
interact to maintain a balance.
- Abiotic components are nonliving chemical and physical factors such as temperature,
light, water, and nutrients.
- Biotic components are living factors such as other organisms.

6. Abiotic factors:
• Those physical and chemical factors which affect the ability of organisms to
survive and reproduce.

7. Some Abiotic Factors:
1. intensity of light
2. range of temperatures
3. amount of moisture
4. type of substratum (soil or rock type)
5. availability of inorganic substances such as minerals
6. supply of gases such as oxygen, carbon dioxide, and nitrogen
7. pH

8. Biotic factors:
• all the living things that directly or indirectly affect the environment
• Thus, the organisms, their presence, parts, interaction, and wastes are all biotic
factors.

9. Each of the prior listed abiotic factors varies in the environment and, as
such, may act as a limiting factor, determining the types of organisms that
exist in that environment.

10. Habitat is generally considered by biologists to be
the physical conditions that surround a species, or
species population, or assemblage of species, or
community (Clements and Shelford, 1939).
The term environment describes, in an unspecified way,
the sum total of physical and biotic conditions that
influence an organism (Kendeigh, 1961).
Ecosystem is perhaps the most widely used term in
ecology. It is defined as the system of organisms and
physical factors under study or consideration.

11. Ecology is not synonymous with environment, environmentalism, natural history, or
environmental science. It is closely related to evolutionary biology, genetics, and
ethology. An important focus for ecologists is to improve the understanding of how
biodiversity affects ecological function. Ecologists seek to explain:
 Life processes, interactions and adaptations
 The movement of materials and energy through living communities
 The successional development of ecosystems
 The abundance and distribution of organisms and biodiversity in the context of the
environment.

12. Ecology has no aim, but ecologists have. The problems of the ecologist are not
fundamentally different from those of any other kind of naturalist. The superficial
differences in aim are due to the different points of view, or methods of approach,
rather than to any essential differences in the character of the problems — (Charles
Adams, 1913; cited in Hedgepeth, 1957).
1. structural, functional, and behavioral adaptations of organisms in relation to their
environment (Chapter 3);
2. interrelationships between species and their populations, and populations in their
communities (Chapter 4);
3. local and geographic distributions of organisms;
4. regional variations in organism abundances;
5. temporal changes in the distribution, abundance, and behaviors of organisms; and
6. evolution of the interrelationships described.

13. There are many practical applications of ecology in conservation biology,
wetland management, natural resource management (agroecology,
agriculture, forestry, agroforestry, fisheries), city planning (urban ecology),
community health, economics, basic and applied science, and human social
interaction (human ecology).