Species richness,endemism, and conservation of American tree ferns (Cyatheales) |
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Authors: | Santiago?Ramírez-Barahona Email author" target="_blank">Isolda?Luna-VegaEmail author Daniel?Tejero-Díez |
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Institution: | 1.Departamento de Biología Evolutiva, Facultad de Ciencias,Universidad Nacional Autónoma de México,Mexico City,Mexico;2.Laboratorio de Evolución Molecular y Experimental, Instituto de Ecología,Universidad Nacional Autónoma de México,Mexico City,Mexico;3.Carrera de Biología, Facultad de Estudios Superiores Iztacala,Universidad Nacional Autónoma de México,Mexico City,Mexico |
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Abstract: | Analyses of richness and endemism of Cyatheales (tree ferns) in tropical America were performed and evidence of a diversity
gradient is presented. For this, the occurrence ranges of 239 species were plotted into a 5° × 5° grid-cell map and then analyzed
using species richness and endemism indices. Here we show that species richness and endemism are not distributed randomly
over the landscape, but do aggregate into defined regions of high diversity in tropical America: the northern Andes, lower
Central America, upper Central America and Mexico, the Guyana Highlands, southeastern Brazil, and the Antilles. These distributional
patterns are congruent with the geographical distribution of cloud forest, which in turn is determined by topography, high
humidity, and persistent cloud immersion. The mountain regions of tropical America, especially the cloud forests, harbour
most of the species of American Cyatheales and have high levels of habitat loss and climatic fragility. Conservation policies
for Cyatheales are centred on the local use and trade of many tree fern species, but none such policies focus on cloud forest
habitat loss. This makes tree ferns a critically endangered group of plants. In the face of the current environmental crisis
and global climate change, the presence of Cyatheales in these regions sounds the alarm on their conservation priorities. |
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