Population Distribution and Abundance Chapter 9 1. Introduction Ecologists usually define a population as a group of individuals of a single species inhabiting a specific area. Characterized by the number of individuals and their density (number per space = # / area .
Plant species vary along an elevation gradient (Merriam’s theorem).
Moisture, temperature limits
As body size increases: pop density decreases
Aquatic invertebrates have higher density than others of same size
Mammals tend to have higher density than birds (food availability).