Biology 1B, Ecology Lecture 8, Page 1 Professor Resh • Spring 2009*Assigned readings, 8th Edition pp. 1214-1216, Review Chapter 547th Edition pp. 1175-1180, 1209-1224Island BiogeographyOutline of Lecture 8A. What is island biogeography?B. Factors that determines number ofspecies on islandsC. Characteristics related to the island size,distance, etc.D. Conservation issuesE. Exotic species introductionsF. Generalization about species richnessA. Factors that determine the number ofspecies that eventually inhabit an island.1. The rate at which new speciesimmigrate to the island from themainland.2. The rate at which species becomeextinct on the island.• Mainland: the place that serves asthe origin of colonizing species.B. Immigration and extinction are alsoeffected by:1. Size of island 2. Distance from mainlandlog of arealogof numberof specieslog of distanceBiology 1B, Ecology Lecture 8, Page 2 Professor Resh • Spring 2009*Assigned readings, 8th Edition pp. 1214-1216, Review Chapter 547th Edition pp. 1175-1180, 1209-1224Island BiogeographyC. Characteristics related to the island size,distance, etc.1. Small islands have lowerimmigration of new species andhigher extinction rates.2. An island closer to the mainland willhave a higher immigration rate.3. Immigration and extinction rates arealso affected by the number ofspecies already present on the island.As number of species on an island increases,immigration of species decreases, and there aremore species to become extinct.4. Exact species composition may vary, andspeciation can also affect composition andequilibrium.Number of species on islandRate of immigrationof new species orextinction of existingspecies on the island“Island” size distance(from “mainland”)Axis labeled as in above cellBiology 1B, Ecology Lecture 8, Page 3 Professor Resh • Spring 2009*Assigned readings, 8th Edition pp. 1214-1216, Review Chapter 547th Edition pp. 1175-1180, 1209-1224Island BiogeographyD. Conservation issues related to this theory1. Communities can change from beingcontinuous large naturalcommunities to “islands” surroundedby unsuitable areas.2. Corridors can be added betweenisland communities anddetermination of appropriate size of“island” (to reduce edge effort)relative to minimum critical size ofhabitat are alternatives.3. Other implications of model (forstudy group discussion)?E. Exotic species introductions (cane toad,Opuntia cactus, mongoose) may effectequilibrium.F. Generalizations about species
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