BIOC50H3 Lecture Notes - Lecture 14: Diversity Index, Umber, Food Web
Document Summary
Lecture 14 (winter 2012) and chapter 15: the nature of communities. Ecologists define communities as groups of interacting species that occur together at the same place and time. Interactions among multiple species are synergistic, which means that they make communities into something more than the sum of their parts. For example, we all know that the human body, made up of various limbs and organs, assumes true structure and function only when all the parts interact. These interactions can be negative, positive, direct, or indirect. A community may be defined by the physical characteristics of its environment; for example, a physically defined community might encompass all the species in a sand dune, a mountain stream, or a desert. Similarly, a biologically defined community might include all the species associated with a kelp forest, a freshwater bog, or a coral reef. Ecologists may use subsets of species to define communities.
