AEC 360     Ecology

Lecture 2:  Structuring Principles

I.  Class organization:  from individuals to ecosystems
Ecology:  The scientific study of the abundance and distribution of organisms in relation to other organisms and environmental conditions (Ricklefs & Relyea, 2014)

A.  The individual organism is the fundamental unit in ecology, evolution, and behavior (see Fig. 1.1 in Ricklefs & Relyea)

B.  A population is

C.  An ecological community includes

D.  An ecosystem includes

E.  The biosphere includes all of the environments and organisms of the Earth

F.   All levels of ecology are governed by biological and physical properties

II.  How do scientists study ecology?

A.  They observe patterns in nature

B.  Observations are the catalyst for scientific progress through the scientific method, which includes:
1.  Observation and description
2.  Develop hypothesis or explanation
3.  Test hypothesis
4.  Apply general knowledge to solve a specific problem

C.  Ecological theories can be represented by mathematical models
1.  They simplify complex systems
2.  They help us identify the key elements and processes to be measured in nature
3.  They generate testable predictions about the ecological system

D.  Scientists test hypotheses through experiments or observation

1.  Testing hypotheses with an observational study:  Effects of forest loss on pine snake populations

-Hypothesis: forest loss reduces snake population sizes
-Null hypothesis: forest loss does not affect population size
-Study: Measure population size in landscapes with different forest area

2.   In experiments, one or a small number of variables are manipulated independently of others to reveal their particular effect

-Habitat loss reduces population sizes because remaining habitats are isolated (unconnected)
-Experiment: Create habitat areas, some of which are connected, and some not connected

III.  How do ecologists communicate their findings:  Interpreting Graphs
A.  Interpreting non-categorical (continuous) data
1.  These data are usually presented in a scatter plot of data, with the independent or causal variable on the horizontal axis (or x-axis), and the dependent variable (the response to the causal variable) on the vertical axis (or y-axis)

2.  There can be variation in the data.  The relationship between the independent and dependent variable can be represented by a line or a curve.  The variation in the data can be viewed as the scatter around this line or curve.

B.  Interpreting categorical data.
1.  These data are usually presented in a bar chart, with the categories on the horizontal axis, and the data on the vertical axis
2.  It is important to notice that there can be variation in the data.  Often, bars will be presented that represent the variability in the data.  Larger bars indicate greater variation, which can make it more difficult to observe differences between categories