Artículo de publicación ISIA high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groupsConsejo Nacional de Ciencia y Tecnologia 000000000011820

The internal transcribed spacer (ITS) region of 18-26S nuclear ribosomal DNA repeat was sequenced for 31 of the approximately 40 species of Clusia known to occur in Panama. Several species from other genera of the Clusiaceae were used as outgroups in the phylogenetic calculation. High sequence alignment and minimal length variation among ITS-1, 5.8S and ITS-2 sequences facilitated determination of positional homology of nucleotide sizes. Sequence alignment was evaluated with character state (Maximum Parsimony) and distance methods (Neighbour Joining). Phylogenetic trees obtained with the two methods were largely concordant and revealed three main groups that roughly correspond to previous arrangements of species into three large morphological groups, the C. flava group, the C. minor group and the C. multiflora group. Because species of Clusia are either regular C 3 plants or exhibit crassulacean acid metabolism (CAM) involving varying proportions of CO 2 fixation in the dark versus the light, we mapped photosynthetic pathways onto the cladograms. Photosynthetic pathway classification was based on measurements of 13 C/ 12 C ratios of plant carbon and also on information available from the literature. Both the C. flava and C. minor group contained species exhibiting CAM, distributed on distinct branches of the cladograms, whereas the third group (C. multiflora group) was composed of species which are not known to use CAM.

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nuestra ilustradora, le debemos dar las gracias por mucho mas que sus excelentes dibujos. Silvia es autora de la mayoria de las ilustraciones hechas especificamente