Abstract
Plant species richness and endemism on oceanic islands is dependent on island age, size, elevation and distance to nearest source of migrants. Mainland ‘island’ systems, such as the cool-adapted tropical-alpine flora of the mountains in Africa, are less well studied. Here we analyse the tropical Afroalpine flora, found on highly isolated mountains straddling the equator. Using the β-sim index in a hierarchical clustering approach combined with ordination methods and mantel tests, we locate four geographical groups: West Africa, northern East Africa, western East Africa and eastern East Africa. We show that these groupings are better explained as the consequence of geographical isolation rather than environmental filtering. We further show that the species richness of the tropical Afroalpine mountain regions—similar to oceanic islands—can be explained by a model including age, area size, elevation and isolation. Levels of endemism are best explained by species richness in combination with area and isolation. Overall we develop a comprehensive model of the species richness, endemism and composition of the tropical Afroalpine flora.
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Acknowledgments
Mike Pirie is thanked for his support and suggestions on an earlier version of the manuscript. The work of B. Gehrke was supported by the German Research Foundation (project no. GE2347/1-1). I would like to thank the two anonymous reviewers for their insightful reviews and helpful comments.
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Gehrke, B., Linder, H.P. Species richness, endemism and species composition in the tropical Afroalpine flora. Alp Botany 124, 165–177 (2014). https://doi.org/10.1007/s00035-014-0132-0
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DOI: https://doi.org/10.1007/s00035-014-0132-0