The Effective Size of a Metapopulation Living in a Heterogeneous Patch Network

Abstract

I analyze stochastic patch occupancy models (SPOMs), which record habitat patches as empty or occupied. A problem with SPOMs has been that if the spatial structure of a heterogeneous habitat patch network is taken into account, the computational effort needed to analyze a SPOM grows as a power of 2n, where n is the number of habitat patches. I propose a computationally feasible approximation method, which approximates the behavior of a heterogeneous SPOM by an "ideal" metapopulation inhabiting a network of identical and equally connected habitat patches. The transformation to the ideal metapopulation is based on weighting the individual patch occupancies by the dynamic values of the habitat patches, which may be calculated from the deterministic mean-field approximation of the original SPOM. Conceptually, the method resembles the calculation of the effective size of a population in the context of population genetics. I demonstrate how the method may be applied to SPOMs with flexible structural assumptions and with spatially correlated and temporally varying parameter values. I apply the method to a real habitat patch network inhabited by the Glanville fritillary butterfly, illustrating that the metapopulation dynamics of this species are essentially driven by temporal variability in the environmental conditions.

Relation between plant species diversity and landscape variables in Central-European dry grassland fragments and their successional derivates

“…The dilemma is commonly referred as SLOSS (single large or several small) and has been widely discussed by many authors (e.g. Ovaskainen 2002, Tjørve 2010, Tscharntke et al 2012). In the case of Goričko Park it is of a crucial importance to preserve the regularly managed medium-and small-sized fragments, which still represent important centres for plant species diversity within the agricultural matrix of Goričko Nature Park.…”

A management-oriented framework for selecting metrics used to assess habitat- and path-specific quality in spatially structured populations

“…However, the model assumptions may not be appropriate for some spatially structured populations. For example, there may be regional synchrony in population dynamics of some species, or colonization and extinction rates may vary over time (Ovaskainen, 2002). Models can be built that account for complexities not included in the basic incidence function model (e.g., disturbance and spatial autocorrelation between habitats (Frank and Wissel, 1998;Kallimanis et al, 2005); asymmetric connectivity (Bode et al, 2008); or the impact of the matrix on dispersal (Watts and Handley, 2010)).…”

Muller’s ratchet in symbiont populations

“…However, if this is the case, it should be possible to add yet another level to the system, and use the progression rate of the ratchet as the mutation rate affecting the local patches of the aphid population. If there is some amount of exchange among patches, the situation becomes more complex, but existing theory (e. g. Levins 1969;Hanski and Gilpin 1997;Ovaskainen 2002;Berg and Kurland 2002) concerning patchy populations can be applied.…”