Theory meets reality: how habitat fragmentation research has transcended island biogeographic theory

Island biogeography theory (IBT) provides a basic conceptual model for understanding habitat fragmentation. Empirical studies of fragmented landscapes often reveal strong effects of fragment area and isolation on species richness, although other predictions of the theory, such as accelerated species turnover in fragments, have been tested less frequently. As predicted by IBT, biota in fragments typically 'relax' over time towards lower species richness. Beyond these broad generalizations, however, the relevance of IBT for understanding fragmented ecosystems is limited. First, IBT provides few predictions about how community composition in fragments should change over time, and which species should be most vulnerable. Second, edge effects can be an important driver of local species extinctions and ecosystem change, but are not considered by IBT. Third, the matrix of modified vegetation surrounding fragments-also ignored by IBT-can strongly influence fragment connectivity, which in turn affects the demography, genetics, and survival of local populations. Fourth, most fragmented landscapes are also altered by other anthropogenic changes, such as hunting, logging, fires, and pollution, which can interact synergistically with habitat fragmentation. Finally, fragmentation often has diverse impacts on ecosystem properties such as canopy-gap dynamics, carbon storage, and the trophic structure of communities that are not considered by IBT. I highlight these phenomena with findings from fragmented ecosystems around the world

Simulations of populations of Sapajus robustus in a fragmented landscape

The study of populations subject to the phenomenon of loss and fragmentation of habitat, transformingcontinuous areas into small ones, usually surrounded by anthropogenic matrices, has been the focus ofmany researches within the scope of conservation. The objective of this study was to develop a com-puter model by introducing modifications to the renowned Penna model for biological aging, in order toevaluate the behavior of populations subjected to the effects of fragmented environments. As an objectof study, it was used biological data of the robust tufted capuchin (Sapajus robustus), an endangered pri-mate species whose geographical distribution within the Atlantic Rain Forest is part of the backdrop ofintense habitat fragmentation. The simulations showed the expected behavior based on the three mainaspects that affects populations under intense habitat fragmentation: the population density, area andconformation of the fragments and deleterious effects due the low genetic variability in small and isolatedpopulations. The model showed itself suitable to describe changes in viability and population dynamicsof the species crested capuchin considering critical levels of survival in a fragmented environment andalso, actions in order to preserve the species should be focused not only on increasing available area butalso in dispersion dynamic