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20 - Survival of species in patchy landscapes: percolation in space and time
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- By Beáta Oborny, Loránd Eötvös University, Budapest, György Szabó, Research Institute for Technical Physics and Materials Science, Budapest, Géza Meszéna, Loránd Eötvös University, Budapest
- Edited by David Storch, Charles University, Prague, Pablo Marquet, Pontificia Universidad Catolica de Chile, James Brown, University of New Mexico
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- Book:
- Scaling Biodiversity
- Published online:
- 05 August 2012
- Print publication:
- 12 July 2007, pp 409-440
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Summary
Introduction
This chapter is about some basic geometric considerations and scaling laws in the spatial structure of habitats and (meta)populations.
Conservation of a valuable species, or conversely, eradication of an invasive species can be significantly helped by mapping its potential habitats. It is not easy, however, to measure the value of a habitat patch for a population or subpopulation. Not only the quality, but also the size and shape of the patch can influence birth, death, migration or dispersal (Forman, 1995; Wiens, 1997; chapter 8 in Turner, Gardner & O'Neill, 2001). The wider context, patch-to-patch neighborhood is another matter of consideration, because it can directly influence the movement of individuals (cf. borderline penetrability; Wiens, 1997) or survival and reproduction (cf. edge effects, ecotone effects; chapter 3 in Forman, 1995; Milne et al., 1996; Harrison & Bruna, 1999). Spatial patterns on larger, regional scales are not negligible either. For example, habitat fragmentation is often a serious threat to survival (Fahrig, 2003). Many species require multiple patch types for completing the life cycle, or performing different activities (e.g. feeding and breeding). In this case, the proximity of different patch types in the patchwork also matters. Finally, the patches are rarely constant: they can shrink, expand, or shift; new patches can appear and old ones disappear. The changes can seriously challenge survival (Keymer et al., 2000; see also Wiens, 1997 about habitat tracking).
4 - Adaptive Dynamics of Speciation: Ecological Underpinnings
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- By Stefan A.H. Geritz, University of Turku, Éva Kisdi, University of Turku, Géza Meszéna, Eötvös University, Johan A.J. Metz, Leiden University
- Edited by Ulf Dieckmann, International Institute for Applied Systems Analysis, Austria, Michael Doebeli, University of British Columbia, Vancouver, Johan A. J. Metz, Rijksuniversiteit Leiden, The Netherlands, Diethard Tautz, Universität zu Köln
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- Book:
- Adaptive Speciation
- Published online:
- 05 July 2014
- Print publication:
- 02 September 2004, pp 54-75
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Summary
Introduction
Speciation occurs when a population splits into ecologically differentiated and reproductively isolated lineages. In this chapter, we focus on the ecological side of nonallopatric speciation: Under what ecological conditions is speciation promoted by natural selection? What are the appropriate tools to identify speciation-prone ecological systems?
For speciation to occur, a population must have the potential to become polymorphic (i.e., it must harbor heritable variation). Moreover, this variation must be under disruptive selection that favors extreme phenotypes at the cost of intermediate ones. With disruptive selection, a genetic polymorphism can be stable only if selection is frequency dependent (Pimm 1979; see Chapter 3). Some appropriate form of frequency dependence is thus an ecological prerequisite for nonallopatric speciation.
Frequency-dependent selection is ubiquitous in nature. It occurs, among many other examples, in the context of resource competition (Christiansen and Loeschcke 1980; see Box 4.1), predator-prey systems (Marrow et al. 1992), multiple habitats (Levene 1953), stochastic environments (Kisdi and Meszéna 1993; Chesson 1994), asymmetric competition (Maynard Smith and Brown 1986), mutualistic interactions (Law and Dieckmann 1998), and behavioral conflicts (Maynard Smith and Price 1973; Hofbauer and Sigmund 1990).
The theory of adaptive dynamics is a framework devised to model the evolution of continuous traits driven by frequency-dependent selection. It can be applied to various ecological settings and is particularly suitable for incorporating ecological complexity.