An Original Theoretical and Empirical Framework for Modelling the Consequences of Habitat Fragmentation on Mammal Population Viability in the Cross-Niger Transition Zone

This dissertation develops an original integrated theoretical and empirical framework for modelling how habitat fragmentation drives population viability loss in medium-to-large mammals in the Cross-Niger Transition Zone, a globally significant biodiversity hotspot spanning Cross River, Ebonyi, and Enugu States. While island biogeography theory and metapopulation models provide conceptual tools for fragmentation analysis, their integration with empirical spatial genetics and telemetry data from West African forest mammals in a predictive management model represents an original contribution. The dissertation employs a four-component methodology: landscape genetic analysis using genome-wide SNP data from six mammal species across 32 forest fragments; GPS collar telemetry on 18 individuals across three species to characterise matrix crossing behaviour; spatially explicit population viability analysis using CDPOP and Vortex with empirically derived connectivity parameters; and a scenario analysis testing 10 conservation intervention strategies. Original theoretical contributions include the Cross-Niger Fragmentation Viability Model (CNFVM), which explicitly incorporates empirically estimated resistance surfaces for matrix habitats and species-specific dispersal abilities. Simulations demonstrate that fragments below 500 hectares have less than 20 percent probability of maintaining viable populations of large-bodied mammals over 50 years without connectivity. Corridor creation between the three largest remaining fragments reduces extinction probability below 5 percent for five of six modelled species. The CNFVM is the first empirically grounded, species-specific fragmentation viability model for Nigerian forest mammals and is designed for direct application in state-level environmental impact assessment. Keywords: habitat fragmentation, population viability, Cross-Niger Transition Zone, landscape genetics, mammal conservation.