No abstract

145 para determinar si hay variación en la adecuación Darwiniana de dos poblaciones. La población de Yotoco presenta dos fenotipos claramente diferenciables por el color (Rosa y Blanco), mientras que en Centenario se encontró solamente el fenotipo Blanco; las flores pueden presentar o no néctar independiente de su fenotipo. Las ofertas florales de R. granadensis se encuentran en el callo del labelo y el nectario de ducto que contiene el espolón o sinsépalo, recubierto por un epitelio glandular compuesto por osmóforos y nectarios. R. granadensis es polinizada por Eulaema sp. que la visita en busca de alimento, es autoincompatible, xenogama obligada y dependiente del polinizador. Mediante simulaciones con matrices demográficas de transición a 50 años y 500 repeticiones se encontró que ambas poblaciones y fenotipos tienden a la extinción en un plazo de 25 años. No se encontraron diferencias entre la adecuación Darwiniana, de los fenotipos de estudio por lo que no se puede probar la existencia de selección fenotípica sobre los caracteres florales. La variación de la especie puede deberse a la deriva génica o la selección dependiente de la frecuencia y la ecología cognitiva del polinizador.

Background and Aims: Orchids in Mexico are mainly threatened by deforestation, changes in land use, illegal trade, deficiencies in environmental policy and legislation, and a lack of community participation in the conservation of their forests. Erycina hyalinobulbon is an endemic twig epiphyte orchid with a short life cycle and with large flowers in relation to its size, for which it has been harvested from its wild populations. The objectives of this work were to evaluate the in vitro development of E. hyalinobulbon in culture media with organic supplements, to compare sucrose vs. N’Joy Stevia® as a carbon source for its initial stages of development, and to evaluate the development of its seedlings in media enriched with plant growth regulators (PGR).Methods: For the sowing of seeds, PhytamaxTM and MS medium at 30% of its basal salts were used in combination with organic supplement (coconut milk, pineapple puree and banana puree), along with the Phy medium used as control. In order to measure the effect of sucrose vs. N´Joy Stevia® as a carbon source, these two treatments were used, with the PhytamaxTM medium. To evaluate the development of seedlings with PGR, three treatments were tested: the 100% PhytamaxTM control, 30% PhytamaxTM with 1.166 ml/l of Maxi-grow and the medium Chiu.Key results: PhytamaxTM medium added with banana promoted germination by 9.3%, being a low cost and easy production option. Ninety days after sowing, N´Joy Stevia® as a carbon source promoted germination by 8%. The best development of the seedlings was registered in the medium PhytamaxTM without PGR.Conclusions: With this study, it was possible to develop an accessible in vitro propagation system for E. hyalinobulbon, in order to sustainably manage it and favor its conservation.

Studying reproductive biology is useful to promote conservation of species. Cuitlauzina pendula La Llave & Lex. is an epiphytic, threatened species. The objectives of this work were to 1) determine if the species requires the visit of pollinators to produce fruits and seeds and 2) evaluate the mating system and reproductive success in terms of fruit production and viability of the seeds. For the evaluation of the mating system, 20 inflorescences were randomly selected, and the following manual pollination treatments were applied: self-pollination, cross-pollination, natural pollination. Another 20 more inflorescences were left uncovered and unmanipulated in order to evaluate natural pollination. Developed fruits were supervised until ripeness. From each of the obtained capsules, the viability of 100 seeds was evaluated with an optical microscope on the basis of the presence and development of embryos, assigning to the seeds the following categories: a: empty; b: developing embryo 1; c: developing embryo 2. Results show low fruit set values for all treatments (5% self-pollination, 7.5% cross-pollination, and 3.16% natural pollination). On the subject of viability of the seeds, treatments showed significant differences with regard to the development categories (X2=247.035, gl=4, P=0.000). Cuitlauzina pendula is a preferably exogamous species that requires pollinators to achieve sexual reproduction, and taking into account that the number of fruits produced with the outcrossing pollination treatment is greater than with the natural pollination treatment, pollination limitation of the species could be considered. ∑ Identificación de bacterias endófitas asociadas a raíces de Vanilla spp. (Orchidaceae)