As the effects of global change keep increasing rapidly, we are urged to improve the predictive power of conservation biology. This requires of an integration of data, statistical tools, and theory. I will illustrate this integrative strategy with recent work on the application of network theory to the conservation of spatial processes at a local, regional and continental scale. For example, while traditional approaches to the characterization of spatial patterns of genetic variation have relied on summary pairwise statistics between pairs of patches, the network approach allows considering the simultaneous influence of all patches. This provides a bottom-up approach to identifying the spatial scale of relevant processes, and the most important habitat patches for the maintenance of spatial processes. I will discuss this framework in the broader context of the range of approaches in theoretical spatial ecology, from spatially implicit to spatially realistic models.
2) Results/Conclusions:
The spatial genetic variation in three out of four Mediterranean plant species is organized in modules defined as groups of patches holding genetically similar populations. Similarly, for the example of the bird migration network across Europe, these modules contain habitat patches that are much more connected by migrating individuals than they are to patches from other modules. In both cases, these modules can be thought of as significant conservation units. Second, these tools of network analysis have identified a few patches that have a disproportionate effect in terms of the global connectivity of the entire network. They act as connectors among different modules, and can largely contribute to the maintenance of gene flow across populations, or to the maintenance of migration flows across the entire landscape. Although related species tend to have a similar organization in spatial modules, the identity of the most relevant nodes for the maintenance of the overall connectivity may change across species, which represents a challenge for conservation. Finally, ongoing work is exploring the temporal dimension of networks of spatial genetic variation in some amphibian species inhabiting highly stochastic environments. This will address how constant in time are these modules and patch connectors.
