Hierarchical analyses of community biogeography in the Afromontane highlands

The Afromontane mountains are a complex series of highlands that have intermittently been connected by habitat corridors during climatic cycles, resulting in a mosaic of range disjunctions and allospecies complexes in the present day. Patterns of community relatedness between geographic regions are often determined through single-species analyses or spatial analyses of diversity and nestedness at the species level. To understand patterns of Afromontane community evolution and to assess the effects of taxonomy on our understanding of biogeographic patterns, I concatenated three different lists of Afromontane bird taxa divided into five different taxonomic hierarchies. These lists were converted into a presence-absence matrix across 42 different montane regions, and analyzed using multiple different clustering techniques using a replicable coding pipeline. I use these lists and methods to determine patterns of relatedness between montane blocks, to assess the consistency with which biogeographic regions are recovered, and to shed more light on patterns of connectivity within the Afromontane region. Results reaffirm the distinctiveness of many different biogeographic regions (i.e., the Cameroon Highlands) while also clarifying regional relationships and the presence of ‘transition zones’ between regions. Differences between lists illustrate how our understanding of taxonomy and distribution in the Afromontane highlands can also change our understanding of Afromontane biogeography. Most notably, I find evidence for an Expanded Eastern Arc that includes the Eastern Arc Mountains and highlands in Malawi, Mozambique, and Zimbabwe. This study presents a rigorous yet easily adjustable pipeline for studying regional biogeography from multiple perspectives with classical and novel approaches.