Ecology – Chapter 1

Ecology – Chapter 1

Ecology Defined:

• total relations of the animal to both its organic and its inorganic environment (Haeckal 1869)

• scientific natural history (Elton 1929)

• study of the structure and function of nature (Odum 1963)

• scientific study of the distribution and abundance of organisms (Andrewartha 1961)

Our Definition:

Ecology – scientific study of the interactions that determine the distribution and abundance of organisms (modification of Andrewartha 1961).

This course will address each of the five key words found in our definition of ecology:

Why this distribution and abundance for this organism?

History of Ecology

• Primitive tribes had to know the ecology of their food

• Biblical plagues

• Pests

Leeuwenhook (1687) counted the number of eggs laid by carrion flies and calculated that one pair of flies could produce 746,496 flies in three months. Is this possible?

Buffon (1756) realized that the great fertility of every species was counterbalanced by innumerable agents of destruction (limits to population growth).

Malthus (1798) calculated that although numbers of organisms increase geometrically, their food supply will never increase faster than arithmetically.

Modern ecology involves all of these ideas.

Ecologist vs. Environmentalistor

Scientist vs. Advocate

Environmentalism is not Ecology – although environmentalist use ecological studies.

Ecological studies can help tell us what will happen when we block the Mississippi from its natural floodplain by building levees, but it will not tell us what we ought to do.

Ecological studies should be done without a political agenda.

Approaches to Ecological Studies

• Descriptive – describes the animals and plants and their interactions within ecosystems. This is the foundation of all ecological science (explains what).

• Functional – studies proximate causes, the dynamic responses of populations and communities to immediate factors of the environment (answers how).

• Evolutionary – considers organisms and the relationships between organisms as historical products of evolution (answers why).

No single approach can answer all ecological answers!

Distribution and Abundance

Eastern Meadowlark

Red Kangaroo

What limits the distribution and abundance of these animals?

Levels of Integration:Landscapes

Ecosystems

Communities

Species

Populations

Individual Organisms

Organ Systems

Organs

Tissues

Cells

Subcellular Organelles

Molecules

Decreasing Scientific Understanding

Levels of Integration:Landscapes

Ecosystems

Communities

Species

Populations

Individual Organisms

Organ Systems

Organs

Tissues

Cells

Subcellular Organelles

Molecules

Decreasing Scientific Understanding

Levels typically addressed by ecological studies

Methods of Approach to Ecology

• Theoretical

• Laboratory

• Field

Scientific Method as Applied to Ecology

• Observation

• Hypothesis

• Experiment

• Conclusion

• Theory

Fig. 1.3