Plant-Herbivore Interactions and Resource Partitioning in the Nyika Plateau, Malawi

Abstract

The Nyika Plateau and its associated national park is the largest protected area in Malawi, encompassing tracts of montane grassland, miombo woodland, and submontane rainforest. As an integral component of the “Afromontane Archipelago,” the Plateau is notable for its high plant diversity and endemism alongside its unique assemblage of large mammalian herbivores. Though the plant community is well documented, there has been little work done to investigate the plant-herbivore interactions of this high-altitude ecosystem. In order to better understand the factors that enable herbivore coexistence and maintain community stability, we used DNA metabarcoding to quantify the diets of six of the most common large mammalian herbivores on the Plateau. By calculating mean diet profiles of each species and comparing the relative similarity/dissimilarity of species’ diets, we were able to assess the degree of intra and interspecific dietary niche partitioning in this community. We found clear signs of dietary niche separation between all six species, both within and outside of traditional diet “guild” assignments. Both species of browser (non-grass feeders) exhibited little dietary niche overlap with each other and the diets of the four grazer species. Grazer (grass feeders) species exhibited limited degrees of dietary overlap but maintained differentiated patterns of clustering among individual diets. This study also presents preliminary results of the first plant DNA barcode database for an Afromontane community, encompassing ~35% of the Plateau’s plant species diversity. Overall, we present a robust characterization of the plant-herbivore interactions in this iconic ecosystem, with broader implications for future study and for conservation.