Metapopulations and Spatial Population Processes

by

Ilkka Hanski

• LAST REVIEWED: 23 May 2012
• LAST MODIFIED: 23 May 2012
• DOI: 10.1093/obo/9780199830060-0054

Introduction

Many habitats have a fragmented spatial distribution at the landscape level, such as networks of ponds in many regions, woodlands, and uncultivated meadows in agricultural landscapes, and parks in cities. Species in such habitats have similarly fragmented distributions; individual habitat fragments may harbor local populations, which together compose a metapopulation, a network of local populations connected by individuals dispersing between the habitat fragments and local populations. Metapopulations are common, because most species have more or less specialized habitat requirements, and their habitats are more or less fragmented. Human land use and other global environmental changes have further fragmented many previously more continuous habitats, and therefore the metapopulation concept has become widely applied in conservation and land-use management. The metapopulation concept was established in the literature in the late 1960s, though some ecologists had formulated ideas about spatially fragmented populations in the early part of the 20th century. Mathematical models have been constructed to study the ecological processes that influence metapopulation persistence. In particular, metapopulations consisting of many small local populations with a high risk of local extinction may persist at the landscape level if the rate of establishment of new populations by dispersing individuals is sufficiently high to compensate for local extinctions. Metapopulation ecology thus highlights the significance of dispersal and recolonization in the dynamics of species, but a range of other factors are also important, including spatial heterogeneity in habitat type, which may lead to local adaptation; temporally changing environmental conditions, which may elevate the risk of extinction; and interactions among different species living in the same network of habitat fragments and that together comprise metacommunities, or local communities connected by dispersal. Metapopulation processes influence the maintenance of genetic variation and the evolution of species at the landscape level. Metapopulation ecology underscores the significance of the spatial structure of the habitat on population processes, but since the 1970s ecologists have realized that spatially restricted dispersal and other population processes may generate spatially aggregated distributions of species in continuous habitats. Ecologists and evolutionary biologists now consider that spatial processes influence the demographic, genetic, and evolutionary dynamics of most species.

General Overviews

There are several edited volumes of metapopulation biology that cover metapopulation ecology as well as genetics and evolutionary biology and that review the development of the field both in terms of theory and empirical studies. Hanski and Gaggiotti 2004 is the latest and most comprehensive of the edited volumes. Hanski 1999 is a monograph on metapopulation ecology, with a focus on classic metapopulations with significant population turnover, local extinctions, and recolonizations, and the relevant models (stochastic patch occupancy models, see also Metapopulation Models). Empirical research on metapopulation biology has been largely restricted to animals because the habitat of many animals has a well-defined patchy distribution, and it is often relatively easy to define what constitutes a suitable habitat independent of the occurrence of the species; the latter is critical for the study of recolonization of currently unoccupied habitats. Husband and Barrett 1996 presents a thorough overview of the application of the metapopulation approach to plants, for which the delimitation of a suitable habitat is often problematic. Over the past decade, the unified neutral theory of biodiversity has received much attention. Rosindell, et al. 2011 reviews the achievements, challenges, and potential of the neutral theory, which is a well-defined theory about spatial dynamics. Thompson 2005 has developed a theory of coevolutionary dynamics, which needs to be mentioned in this context because it assumes that the spatial structure and dynamics of populations play a critical role in their evolution and that the ecological metapopulation dynamics and evolutionary dynamics may influence each other.

• Hanski, Ilkka. 1999. Metapopulation ecology. New York: Oxford Univ. Press.

  A monograph of metapopulation ecology, covering both theory and empirical studies, with a section on the Glanville fritillary butterfly as a model system. Written for advanced students and researchers.

• Hanski, Ilkka, and Oscar Gaggiotti, eds. 2004. Ecology, genetics, and evolution of metapopulations. Amsterdam: Elsevier Academic.

  This is the most recent edited volume on metapopulation ecology, genetics, and evolution, with twenty-three chapters covering both metapopulation theory and empirical studies and a wide range of taxa and specific topics. Several chapters are quite technical, but other chapters are appropriate for advanced students.

• Husband, Brian, and Spencer Barrett. 1996. A metapopulation perspective in plant population biology. Journal of Ecology 84.3: 461–469.

  DOI: 10.2307/2261207

  A pioneering overview of the application of the metapopulation concept and approaches to plants, discussing the particular features of plants that may make a difference in this context: seed dormancy, restricted dispersal, and local adaptation.

• Rosindell, J., S. P. Hubbell, and R. S. Etienne. 2011. The unified neutral theory of biodiversity and biogeography at age ten. Trends in Ecology & Evolution 26.7: 340–348.

  DOI: 10.1016/j.tree.2011.03.024

  Reviews the “unified neutral theory of biodiversity” at the age of ten years. The neutral theory presents one approach to the study of spatial dynamics. Many researchers are enthusiastic about it, but others are doubtful about the power of the neutral theory to explain the spatial dynamics of species in the wild.

• Thompson, John. 2005. The geographic mosaic of coevolution. Chicago: Univ. of Chicago Press.

  Outlines a conceptual framework for coevolution in the spatial context, and thereby this book has much to offer to students and researchers interested in the evolution of metapopulations.