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The Sanje mangabey (Cercocebus sanjei) is a primate species that is endemic to the Udzungwa \ud Mountains, Tanzania. The species is classified as Endangered due to its putatively declining population \ud size, limited habitat extent, and habitat fragmentation. The species is divided into two populations: one \ud isolated to the Mwanihana forest fragment in the Udzungwa Mountains National Park, and one to the \ud Uzungwa Scarp Nature Reserve forest. The population in Mwanihana is well-protected under National \ud Park regulations, however the Uzungwa Scarp is considerably lesser protected under Nature Reserve \ud regulations. The Sanje mangabey was described in 1979 and studies have been conducted to increase \ud our understanding of the species since, but many knowledge gaps remain. This thesis aimed to address \ud the priority gaps in our understanding to inform conservation action planning. This included \ud conducting the first systematic population survey for the species, and to investigate the genetic \ud diversity and structure of the two populations. Additionally, it has been previously argued whether the \ud Sanje mangabey should be considered at species or subspecies (C. galeritus sanjei) level due to its \ud behavioural similarities to other central/east African Cercocebus mangabeys. Firstly, we developed a \ud novel acoustic survey method for systematically and more effectively surveying the Sanje mangabey. \ud We estimated the total population size to be 3,167 individuals (95% CI: 2,181-4,596) and found a \ud significantly lower group density in the Uzungwa Scarp forest than Mwanihana. Secondly, we estimated \ud the phylogenetic history of the species and unexpectedly found the Sanje mangabey to be an \ud evolutionarily distinct lineage from other Cercocebus mangabeys, diverging 2.17 MYA. Further \ud unexpected results from this study was the designation of the two populations as evolutionarily \ud significant units, having diverged 0.71 MYA. Thirdly, we investigated the phylogeographic structure of \ud the two populations using mitochondrial DNA and found the populations to be significantly \ud differentiated. Further, an ecological niche model combined with a study of the demographic history of \ud each population revealed the populations to have remained stable in recent history, reflective of the \ud environmental stability of the montane forests in the Udzungwa Mountains. Finally, combining life \ud history data with estimated threats to viability for the Sanje mangabey, we estimated loss of habitat to \ud be the greatest threat to each population and therefore conservation recommendations were made \ud based on these results. The results of this thesis will be used to inform conservation management \ud development for the Sanje mangabey within the Mangadrill Conservation Action Plan, with priority \ud placed on the need to increase protection of the evolutionarily significant population in the Uzungwa \ud Scarp forest. |
