Habitat destruction and fragmentation in tropical forests are the single largest threat to the planet's biodiversity. The roles of genetic and demographic factors in the extinction of small populations in fragmented habitat patches are understood in theory but poorly documented empirically. To test existing theory and to improve techniques of biodiversity conservation, the investigators will develop a new method of monitoring population viability in recently fragmented populations. Specifically, they will conduct population viability analyses of rat, tree shrew, and other small mammal populations in small rainforest patches of different sizes during the first six years following isolation. These habitat patches were all isolated in 1987 when the creation of the Chiew Larn reservoir flooded a forested valley in the Khlong Saeng Wildlife Sanctuary, Thailand, and created 165 islands. Demographic changes in selected populations will be monitored by seasonal live-trapping as will levels of genetic variation, inbreeding and gene flow. The study is novel in that the genetic changes will be monitored at the DNA sequence level with DNA obtained non-invasively from plucked hair. This study will contribute to our basic understanding of evolutionary biology and ecology in a number of ways. It will provide among the first sequence-level data on variation in a number of nuclear and mitochondrial genes in several free- ranging mammal species. It will also provide one of the first cases where both genetic and ecological aspects of population viability are monitored in the critical first 20 generations following insularization. In addition, the study promises to contribute to conservation biology in three significant ways. First, the development of the genetic monitoring technique based on non-invasive sampling of DNA from hair will have wide applicability. Second, the demonstration that population viability can be monitored in common small mammals should lead to improved management practices for rarer and more endangered species. Finally, the lessons learned from this study in Thai forest fragments should be applicable to biodiversity conservation elsewhere in the tropics.
