Metapopulation Dynamics and the Quality of the Matrix

Abstract

In both strictly theoretical and more applied contexts it has been historically assumed that metapopulations exist within a featureless, uninhabitable matrix and that dynamics within the matrix are unimportant. In this article, we explore the range of theoretical consequences that result from relaxing this assumption. We show, with a variety of modeling techniques, that matrix quality can be extremely important in determining metapopulation dynamics. A higher-quality matrix generally buffers against extinction. However, in some situations, an increase in matrix quality can generate chaotic subpopulation dynamics, where stability had been the rule in a lower-quality matrix. Furthermore, subpopulations acting as source populations in a low-quality matrix may develop metapopulation dynamics as the quality of the matrix increases. By forcing metapopulation dynamics on a formerly heterogeneous (but stable within subpopulations) population, the probability of simultaneous extinction of all subpopulations actually increases. Thus, it cannot be automatically assumed that increasing matrix quality will lower the probability of global extinction of a population.

Competition–colonization dynamics in experimental bacterial metacommunities

“…7), suggesting the existence of an 'extinction debt' 9 . This situation illustrates the susceptibility of communities structured by the CC trade-off to the changes in absolute colonization rate that are predicted under human impacts on landscapes, including habitat destruction 9,40 , fragmentation 8 or changes in inter-habitat matrix quality 41 . Previous experimental studies have been limited to binary or coarse-scale manipulations of colonization rate to simulate reductions in landscape connectivity 42,43 .…”

The agroecological matrix as alternative to the land-sparing/agriculture intensification model

“…Furthermore, a great deal of conservation biology now concerns itself with the quality of the matrix, partially because of the significant amounts of biodiversity that may be contained therein but especially because interfragment migration is necessary for metapopulation survival (33,(42)(43)(44)(45)(46)(47)(48)(49)(50). In previous work (44), the limited nature of the classic metapopulation approach has been noted, especially with respect to its assumption that the matrix in which subpopulations are situated is homogeneous, showing one way in which that assumption could be relaxed-that is, by allowing the quality of the matrix to enter the basic equation as a linear input to the migration rate. The framework presented here expands on that relaxation by focusing on h, a focus explicitly relevant to anthropogenic landscapes but retaining the heuristic convenience of the mean-field approach.…”

“…It is worth noting also that, as in the standard metapopulation model, when p is very small it is especially sensitive to changes in migration and extinction rates. This approach, using the simple mean-field metapopulation model, only relates to the question of persistence or extinction of a particular species, and is, effectively, an extension of previous approaches (40,44). Scaling up to the community level is in the realm of metacommunity theory (51).…”

Conservation of the Ethiopian church forests: Threats, opportunities and implications for their management

“…Spatially targeted expansion of such buffer zones and establishment of new forest patches within the matrix located at distances compatible with dispersal distances of trees may play an important role in increasing the quality of the matrix (see e.g. Lemenih and Bongers 2010;Telila et al 2015), thereby decreasing the functional isolation of species' populations within a network of forest patches and reducing the risks of extinction (Vandermeer and Carvajal 2001;Berens et al 2014).…”