Effects of temporal variability of spatial networks on meta-community food-web stability and diversity

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In this project we will study the structure and stability of complex trophic networks on a spatial network of habitat patches (meta-food webs). We will concentrate on the effects of temporal variability of the spatial network structure on species diversity and population stability at local and regional scales. The trophic networks on local habitat patches are formed by the feeding interactions between the species. The spatial network consists of isolated patches (nodes) in a non-continuous landscape. Links in the spatial network are formed by the ability of species to disperse over certain distances between different habitat patches. The availability of patches as habitats for local communities and the accessibility of dispersal routes will vary over time, thereby changing the structure of the spatial network. We will use computer-generated trophic and spatial networks and simulate the population dynamics of the species with ordinary differential equation (ODE) models. The survival of species on a patch is determined by the consumption of resources to cover metabolic demands and by mortality from predation, which both depend on the composition of the local community. The persistence of species in the regional landscape will depend on their ability to disperse between different habitats and colonise suitable patches. The proposed project consists of three work packages that address different types of temporal variability of the spatial network structure: (1) Spatial networks with periodically blinking links. Dispersal between patches is not always possible, but only during certain time periods (e.g. the mating season when mobile ontogenetic stages emerge). We expect that differences in the species composition among local communities will prevail if they are temporarily isolated from each other. (2) Spatial networks with blinking nodes. Not all patches will be constantly available as habitat for a local community and may become completely uninhabitable for some time (e.g. small ponds that dry out during the summer). This disrupts the spatial network for species with limited dispersal capability. We will study how different temporal patterns of blinking (e.g. synchronous or asynchronous) of either strongly or weakly connected patches affects species persistence and synchronism of population oscillations throughout the meta-food web. (3) Variable environmental conditions and adaptive dispersal. The fitness of a population (its net growth rate) depends on the composition of the local community and on environmental conditions such as temperature or availability of basal resources in the patch. We will investigate how adaptive dispersal of species (e.g. emigration from a patch only if net growth is negative) in response to temporal variation of local environmental conditions drives dispersal patterns and meta-community wide variability of population abundances.