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Ultramafic ecosystems are renowned for high endemism and habitat specialization. However, most of our understanding of ultramafic plant ecology comes from Mediterranean and temperate climes, raising questions about the generalizability of plant responses to ultramafic soils. This is especially apparent in tropical ultramafic ecosystems which exhibit a wide range of endemism and differentiation between ultramafic and adjacent non-ultramafic soils. Our objectives were two-fold: 1) synthesize our understanding of tropical ultramafic plant ecology, paying particular attention to generalities that may explain variation in endemism and habitat specialization among tropical ultramafic ecosystems; and 2) define an interdisciplinary research agenda using tropical ultramafic ecosystems as a macroecological model. We demonstrate that tropical ultramafic floras are diverse and variable in plant form and function due to the interactive effects of biogeography, climate, and edaphic properties. The variable rates of endemism, specialization, and stress tolerance traits across tropical ultramafic ecosystems have implications for the management and conservation of these diverse systems. Los ecosistemas ultramaficos son reconocidos por su endemismo y especializacion del habitat. Sin embargo, la mayor parte de nuestra comprension de la ecologia vegetal ultramafica proviene de climas mediterraneos y templados, lo que plantea dudas sobre la generalizacion de las respuestas de las plantas a los suelos ultramaficos. Esto es especialmente evidente en los ecosistemas tropicales ultramaficos que exhiben una amplia gama de endemismo y diferenciacion entre suelos tropicales ultramaficos y no ultramaficos adyacentes. Nosotros teniamos dos objetivos: 1) sintetizar nuestra comprension actual de la ecologia de las plantas tropicales ultramaficas, prestando especial atencion a las generalidades que pueden explicar la variacion en el endemismo y la especializacion del habitat entre los ecosistemas tropicales ultramaficos; y 2) definir una agenda de investigacion interdisciplinaria utilizando ecosistemas ultramaficos tropicales como modelo macroecologico. Las floras tropicales ultramaficas son diversas y variables en la forma y funcion de las plantas debido a los efectos interactivos de la biogeografia, el clima y las propiedades edaficas. Las tasas variables de endemismo, especializacion y rasgos de tolerancia al estres en los ecosistemas tropicales ultramaficos tienen implicaciones para el manejo y conservacion de estos diversos sistemas. Keywords Edaphic * Endemism * Hyperaccumulator * Metallophyte * Serpentine * Unusual soil, Introduction Ultramafic (serpentine) soils have long attracted scientific attention due to their specialized flora and ecological and evolutionary implications. However, our understanding of ultramafic plant ecology remains dominated by research [...]

Summary: Orchids constitute one of the most spectacular radiations of flowering plants. However, their origin, spread across the globe, and hotspots of speciation remain uncertain due to the lack of an up‐to‐date phylogeographic analysis.We present a new Orchidaceae phylogeny based on combined high‐throughput and Sanger sequencing data, covering all five subfamilies, 17/22 tribes, 40/49 subtribes, 285/736 genera, and c. 7% (1921) of the 29 524 accepted species, and use it to infer geographic range evolution, diversity, and speciation patterns by adding curated geographical distributions from the World Checklist of Vascular Plants.The orchids' most recent common ancestor is inferred to have lived in Late Cretaceous Laurasia. The modern range of Apostasioideae, which comprises two genera with 16 species from India to northern Australia, is interpreted as relictual, similar to that of numerous other groups that went extinct at higher latitudes following the global climate cooling during the Oligocene. Despite their ancient origin, modern orchid species diversity mainly originated over the last 5 Ma, with the highest speciation rates in Panama and Costa Rica.These results alter our understanding of the geographic origin of orchids, previously proposed as Australian, and pinpoint Central America as a region of recent, explosive speciation. [ABSTRACT FROM AUTHOR]