On the identification of areas of endemism in the Neotropical montane cloud forests: A comparative review

Neotropical montane cloud forests are terrestrial ecosystems characterized by a consistent high humidity from clouds or mist. Geographically, these forests occur along the Andes, Mesoamerica, and the Caribbean mountain ranges. They have a complex biogeographic history, reflected in their great biodiversity, which includes a high proportion of endemic species. Over the last three decades, several studies examining the spatial distributional patterns of different biological groups have provided valuable insights into identifying areas of endemism in these forests. These analyses differ in terms of taxa, inclusion criteria, methods, spatial scales, and operational geographic units, revealing both shared and contrasting results. Based on a comprehensive review and comparative synthesis of previously published biogeographic studies, we compared recent contributions that describe distributional patterns of fungi, plants, mammals, amphibians, birds, and insects restricted to the Neotropical montane cloud forest. We identified seven well-supported areas of endemism and three additional regions as potential areas of endemism, and we provide a list of endemic taxa diagnosing these natural biotic units. The areas of endemism detected in the montane cloud forest of America correspond to their main mountain chains: (1) Northeastern Mexico, (2) Western and Central Mexico (3) Southern Mexico, (4) Eastern Mexico to north-central Nicaragua, (5) Northwestern South America, including the Sierra Nevada de Santa Marta and Serranía de Perijá, (6) Western South America, and (7) Southern Andean Yungas. Each of these regions encompasses different levels of species richness and composition. Comparing areas of endemism across phylogenetically unrelated taxonomic groups enables us to test hypotheses about the shared history of sympatric species. Furthermore, these areas of endemism have important implications for conservation, particularly where regions of high richness across different biological groups overlap. The quality and quantity of data available for each biological group condition the delimitation of areas of endemism between different taxonomic groups. The factors that influence the delimitation of these areas include the delimitation and taxonomy of species, data gaps or unsampled regions, as well as biogeographic methods and the size unit used to delimit areas of endemism. There is no standard in the parameters for delimiting areas of endemism (grid origin, species score, endemism index, among others) to provide a starting point of comparison. Our review found at least four areas of endemism for the Mesoamerican cloud forest and three areas of endemism for the cloud forest of South America. The overlap among previously reported areas of endemism (using various methods and spatial scales) suggests that these regions harbor a high degree of endemism across different biological groups, including both restricted and shared taxa, indicating a common biogeographic history.