In present times, there is a clear and growing need for applying theoretical biogeographic achievements in improving the state of biodiversity and conservation. Conceptual principles of conservation biogeography take the research into the relationship between fundamental biogeographic principles and the need for their appliance in nature conservation as the basic theory model, based upon biogeographic studies of isolated ranges. This paper is meant to point out the differences between spatial and functional isolation and the effects these have on the stability of populations and species. In light of this need to apply theories in biodiversity and nature conservation, it is important to research not only the processes that depend solely upon natural factors, but also those that are caused by a number of human-induced changes, e.g. habitat fragmentation, climate change or biotic homogenization.