This Project aims to provide a better understanding of the causes and consequences of species responses to habitat loss and fragmentation. To address this goal, this Project will use an extensive dataset of more than 10,000 birds and small mammals captured in 65 forest patches of different sizes and connectivity located in six landscapes of the Atlantic Forest of São Paulo, Brazil (three continuous landscapes with over 90% forest cover and three fragmented landscapes with 10, 30 and 50% forest cover respectively). This dataset will be analysed to determine: (i) which assembly rules are structuring communities, and do these rules change with habitat loss and fragmentation or among taxa; (ii) how community disassembly caused by habitat loss and fragmentation affects functional diversity; (iii) which species are more important for ecosystem functioning; (iv) the existence of extinction and functional diversity thresholds; and finally, (v) to determine the minimum area requirements necessary to sustain a viable and functional tropical forest ecosystem. These questions will be tested with the use of analytical frameworks developed in several areas within biology, drawing together advances in phylogenetics, population biology, community ecology, landscape ecology, and multivariate statistics. Therefore, this Project aims to advance the scientific understanding of the processes that govern community dynamics in fragmented landscapes and the consequences of landscape alteration for maintaining a functional ecosystem, and will generate solid predictions that can be used for building objective and accurate conservation strategies in this imperilled ecosystem.