Introduction to Ecology
Definition –what is ecology?
What are the branches of ecology?
What do ecologists do? (two examples)
The Scientific Method (a cautionary tale)
Why study ecology?
Reading: Chapter 1 (all pages)
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Introduction to Ecology
Definition – what is ecology?
What are the branches of ecology?
What do ecologists do? (two examples)
The Scientific Method (a cautionary tale)
Why study ecology?
Reading: Chapter 1 (all pages)
What is ecology?
• Taken from the Greek words
- oikos = “house”
- logy = “the study of”
• Ecology = the scientific study of the
relationships between organisms & their
environment. (“Biology in context”)
- Includes:
- Physical conditions experienced by an organism = abiotic
- The biological or living components that make up an organism’s surroundings = biotic
Other definitions:
• Ecology studies the “factors affecting the
density and distribution of organisms” (a good
definition of population ecology, but less good
for other subdisciplines)
Ecology vs. “Natural History”
- Natural history provides a
descriptive account of organisms
and their environment (a historical
and conceptual foundation for
ecology, but not ecology per se )
- Ecology is a quantitative science that tests
hypotheses, and often incorporates theory (e.g.
evolution by natural selection).
(see page 2 in your text)
http://www.amazon.com/
Branches of Ecology:
• Hierarchical organization – according to level of
organization
• Conceptual organization – according to
theoretical construct or processes studied
• Taxonomic – according to organisms studied
• Time/Place - According to time/place
• Methodological organization – according to
method used (or technology used)
• Theoretical vs. applied (problem solving) - etc.-
Hierarchical Structure of Ecological
Systems
- Organism = fundamental unit of ecology.
- No smaller unit in biology has an independent life in the environment.
- Population = a group of individuals of a single species inhabiting a specific area (c.f. all the individuals of a given species)
- Community = an association of interacting species living in a particular area.
- Ecosystem = a biological community plus all of the abiotic factors influencing that community.
- Biosphere = the aggregation of all ecosystems (the sum of all of the organisms of the earth and their environment). The living zone of the planet.
Temporal & spatial scales are
often linked
Time
----------- Ecophysiology ------------
------ Population Ecology -------
Community & Landscape Ecology
-------- Global Ecology --------
sec/min/hour day/wk year century millenia etc.
mm
m
km
Whole
Earth
What level of ecological hierarchy is illustrated?
Customer image on Amazon.com (from the Heyday of Natural History)
( it depends upon the question !)
Examples of “Conceptual” Divisions in
Ecology:
- Descriptive (e.g. natural history approach)
- Functional (according to functional properties)
- Evolutionary ecology (according to
evolutionary concepts)
…leading to other types of questions …
Other Classes of Ecological Questions
1. What Questions: ( Descriptive ecology )
- What organisms & environments occur in a given area?
What are their distributions? What are their quantities?
2. How Questions: ( Functional ecology )
- How are organisms & environments functionally related?
How are relations similar & different in similar/different
ecosystems?
3. Why Questions: ( Evolutionary ecology )
- Why are organisms functionally related to each other &
their environments in certain ways & not others? or in
certain ecosystems & not others?
Two examples from the text (Ch. 1)
Example 1: Ecology of Forest Birds
• MacArthur (1958) studied the ecology of five
species of warblers in spruce forests in North
America
- Predicted that species with identical ecological
requirements could not coexist indefinitely ( due to
competitive exclusion ).
- Divided trees into zones & determined how much
time individuals of each species spent in each
zone.
Warbler Feeding Zones
- Found that warblers were able to coexist by feeding in
different zones of trees.
- Morse (1980) found that aggression between warbler
species maintained their distinctive feeding zones.
Fig. 1. Molles & Cahill 2008
Example 2: Ecosystem Experiment
- What causes clear lakes to undergo eutrophication and
become cloudy?
- Eutrophication = nutrient enrichment of a lake which can cause rapid algal growth & ↓ oxygen levels.
- Algae clearly were growing because of nutrient additions, but what nutrient?
- Lab experiments were inconclusive so whole-lake experiments were needed.
- Schindler (1974) led experiments involving additions of nutrients to entire lakes in the Experimental Lakes Area (ELA) in Ontario.