Biology 2483A Lecture Notes - Lecture 15: Trophic Cascade, Genetic Diversity, Kelp Forest

• School: Western University
• Department: Biology
• Course: Biology 2483A
• Professor: Hugh Henry

Document Summary

Although so far we have considered species interactions in two-way relationships, in reality, species experience multiple interactions that shape the communities in which they live. Communities are groups of interacting species that occur together at the same place and time (ecologists usually define communities based on physical or biological characteristics). Physically- defined communities might encompass all the species in a sand dune, a mountain stream, or a desert. Biologically-defined communities might include all the species associated with a kelp forest, a freshwater bog, or a coral reef (emphasizes the importance of abundant species). A study of marine invertebrates in seagrasses might restrict the definition of the community to that interaction, and not include mussel-eating birds (definition of communities is somewhat arbitrary). Ecologists usually consider a subset of species when they define and study communities as counting all species in a community is near impossible. Food webs organize species based on trophic or energetic interactions.