This is a preview. Log in through your library. Show Abstract The development of the equilibrium theory of island biogeography and its basic concepts are outlined. Studies purporting to validate the theory are critically examined, and it is concluded that there is little support for its tenets. The application of the theory to nature conservation and ecology is therefore premature. Journal Information The subjects of biogeography, ecology and biodiversity are now of truly global importance. Recognizing this increased significance, the scope of the Journal of Biogeography and its sister publications, Global Ecology and Biogeography and Diversity and Distributions, continue to be developed under the guidance of Dr Robert Whittaker and Dr David Richardson respectively, acting as a team with Professor Philip Stott, the Editor of Journal of Biogeography. All three journals have wide coverage–from 'enhanced global warming' to the distribution of gadoid fishes, from invertebrate diversity in tropical rain forests to individualist species responses–so that all the key biogeographical and ecological questions of the day may be addressed. Topics include 'what is naturalness?', debates on both philosophy and methods, the implications of ecosystem fragmentation, the impact of human-induced changes, as well as the ecological and economic significance of biodiversity. All systematic groups are also embraced, from theory to practice, from plants to animals. Journal of Biogeography is essential reading for all environmentalists, biogeographers, ecologists, biologists, botanists and zoologists. JSTOR provides a digital archive of the print version of Journal of Biogeography. The electronic version of Journal of Biogeography is available at http://www.interscience.wiley.com. 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Wiley has published the works of more than 450 Nobel laureates in all categories: Literature, Economics, Physiology or Medicine, Physics, Chemistry, and Peace. Wiley has partnerships with many of the world’s leading societies and publishes over 1,500 peer-reviewed journals and 1,500+ new books annually in print and online, as well as databases, major reference works and laboratory protocols in STMS subjects. With a growing open access offering, Wiley is committed to the widest possible dissemination of and access to the content we publish and supports all sustainable models of access. Our online platform, Wiley Online Library (wileyonlinelibrary.com) is one of the world’s most extensive multidisciplinary collections of online resources, covering life, health, social and physical sciences, and humanities. Rights & Usage This item is part of a JSTOR Collection. Equilibrium Theory of Island Biogeography NRE 220 Lecture 15 Corresponding Readings in Primack, Richard B. Essentials of Conservation Biology. Species-Area Relationship We are now moving from a discussion of genetics, populations, and species to communities and ecosystems. The next few lectures will describe concepts of major importance to conservation in terms of the effects of habitat fragmentation and maintenance of species diversity. A great deal of conservation research has been done on islands, because they are small, replicated units of area, isolated from other habitat. They are very useful for species, community, and ecosystem studies. Early observations of biogeography involved the examination of the geography of biodiversity around the globe. This was followed by recognition of the species-area relationship - as area increases, the number of species present (diversity) also increases. This can be represented by one of two graphs, depending on the axes used: 1) a concave, upward slope (# of species vs. area) or 2) a straight, upward sloping line (log(# of species) vs. log(area)). If we use the second form of the graph, we find that the equation describing the line is log (S) = log (c) + z log(A) where z represents the slope. What factors influence z? - Climate, e.g. latitudinal gradient factors - High average r across the community or group of species - Habitat complexity - Isolation, e.g. distance from the mainland - Type of species represented, e.g. mammals vs. birds Data collected by Harris for mountaintop islands in the Great Basin show that mammals have a higher z (steeper slope on the species-area graph) than birds. Equilibrium Theory of Island Biogeography (ETIB) The ETIB describes the theoretical relationship between immigration and extinction of species to islands, depending on their size and distance from the mainland or other species source. Consider the degree of isolation of the area under study: Isolate (oceanic and continental islands) vs. Sample (e.g. Amazon) Oceanic islands are usually created by volcanic activity. Continental islands are formed when the water level rises (e.g. glaciers melt). How do species access these islands over time? 1) On oceanic islands, the number of species present increases over time until it reaches the level of the nearest mainland (theoretically the source of the species which immigrate to the island). 2) On continental islands, the number of species present decreases over time. Species richness "relaxes" to a new equilibrium depending on the degree of isolation and the size of the island. According to ETIB, the number of species present on an island is determined by a balance between immigration and extinction. Generally, as the number of species present increases, the immigration rate decreases and the extinction rate increases. There are two general relationships to remember: 1) Immigration is higher on near islands than on distant islands (in relation to the mainland), hence the equilibrium number of species present will be greater on near islands. 2) Extinction is higher on small islands than on larger islands, hence the equilibrium number of species present will be greater on large islands. Therefore, The number of species on near, large islands > The number of species on distant, small islands Work by Simberloff and Wilson on mangrove islands in Florida has validated the ETIB: They killed all of the organisms on various sizes of mangrove islands and different distances from the "mainland" source of species and measured recolonization rates. They found that near, large islands experienced faster recolonization than distant, small islands. Much of ETIB, which was founded on the study of true islands, can be extended to islands in fragmented habitat. Island biogeography has become an essential component of conservation biology, particularly in the analysis of preserve design, which will be covered in the next lecture. Links: Spotlight on Island Biogeorgraphy: a good, concise summary of Island Biogeography. Edge Effects and the Extinction of Populations Inside Protected Areas Rain Forest Fragments Fare Poorly Heeding the Warning in Biodiversity’s Basic Law Self-Similarity in the Distribution and Abundance of Species Biomass Collapse in Amazonian Forest Fragments What is true of the theory of island biogeography?The theory of island biogeography predicts that the number of plant and animal species on an island is related to the area of the island's landmass and the degree of isolation of the island. The theory states that smaller, more isolated islands have fewer numbers of plant and animal species. The converse is also true.
Which statement about the equilibrium theory of island biogeography is false?Which statement about the equilibrium theory of island biogeography is false? At equilibrium, the species composition of an island will not change.
How does island size and distance from the mainland determine biodiversity?Thus, the biodiversity found on an island is a function of (1) how close the island is to the mainland, and (2) how large the island is. As you might imagine, larger islands tend to have more species than smaller islands because there is greater habitat diversity and, therefore, more resources available.
What is island biogeography quizlet?island biogeography definition. field of study on the factors that affect species richness in natural communities based on habitat isolation, area, immigration, and extinction dynamics.
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Which statement comparing island biogeography to mainland biogeography is true?
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