Biology 2483A Lecture Notes - Lecture 15: 16S Ribosomal Rna, Diversity Index, Species Evenness
29 Feb 2016
School
Department
Course
Professor
Document Summary
Communities are groups of interacting species that occur together at the same place and time. In practical terms, ecologists usually define communities based on physical or biological characteristics. A physically defined community might encompass all the species in a sand dune, a mountain stream, or a desert. A biologically defined community might include all the species associated with a kelp forest, a freshwater bog, or a coral reef. This approach emphasizes the importance of an abundant species, such as trees. Ecologists often define a community somewhat arbitrarily, based on the questions they are posing. A study of marine invertebrates in sea grasses might restrict the definition of the community to that interaction, and not include mussel-eating birds, etc. Counting all the species in a community is difficult to impossible, especially if small or unknown species are considered. Ecologists usually consider a subset of species when they define and study communities. Taxanomic affinity: all bird species in a community.
