1. Scope of Ecology
Ecology (from Greek word oikos “household” and logos “study of”)
Is the scientific study of the distribution, abundance and relationship between organisms and their environment
Environment
Includes not only the physical but also the biological conditions under which an organism lives

2. Relationship
Includes interactions with the physical world and with members of other species and the same species
The term ecology was coined by the German zoologist Ernst Haeckel in He called it Oecologie and defined its scope as the study of the relationship of animals to their environment.

3. Environmental Science
an interdisciplinary academic field that integrates physical and biological sciences (including physics, chemistry, biology, soil science, geology, and geography) to the study of the environment, and the solution of environmental problems.
Environmental science provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems

4. Ecosystem
Organisms interact with their environment within the context of the ecosystem.
Eco – relates to the environment
System – a collection of related parts that function as a unit.
Ecosystem consists of two basic interacting components:
biotic (living)
abiotic (physical)

5. Ecosystem components form a hierarchy
All organisms of a given kind constitute a species. Each species represents a particular array of hereditary material called a gene pool, which is distinct from the gene pools of other species.
Populations – groups of individual organisms of the same species that interbreed and occupy given areas at given times. Each organism and population has a habitat, the place where it lives.

6. Community – populations of plant and animals species living and interacting in a given area at a given time.
Ecosystem – community of living things that interact with each other and with the physical environment.
Biosphere – combination of all ecosystems

7. The Organism and its Environment
Fundamental ways the organism relates to its environment
Environmental conditions vary both in time and space
All organisms live in a varying physical environment of temperature, moisture, light, and nutrients.

8. Homeostasis is possible only within a limited range of conditions
Organisms need a fairly constant internal environment
Homeostasis – the maintenance of conditions within the range that the organism can tolerate
Homeostasis is possible only within a limited range of conditions
Leibig’s law of the minimum (the performance of an organism will be a function of the most limiting environmental factor)

9. An organism cannot do equally well in differing environments
The characteristics that enable an organism to do well under one set of conditions limit its performance under a different set of conditions.
The distribution of organisms reflects environmental variation

10. Environmental components
Affect the distribution and abundance of organisms
Kangaroos/km2
> 20
10–20
5–10
1–5
0.1–1
< 0.1
Limits of distribution
Climate in northern Australia
is hot and wet, with seasonal
drought.
Red kangaroos
occur in most
semiarid and arid
regions of the
interior, where
precipitation is
relatively low and
variable from
year to year.
Southeastern Australia
has a wet, cool climate.
Southern Australia has
cool, moist winters and
warm, dry summers.
Tasmania
Figure 50.2

11. An organism lives in a habitat
The actual location or place where an organism lives is called its habitat
Constraints and trade-offs in habitat use define an organism’s niche
The basic role of an organism in the community – what it does, its relationship to its food and enemies (species occupation)
Includes all the physical and biological variables that affect an organism’s well-being