Mexican oregano (Lippia graveolens) is an important aromatic plant, mainly used as flavoring and usually harvested from non-cultivated populations. Mexican oregano essential oil showed important variation in the essential-oil yield and composition. The composition of the essential oils extracted by hydrodistillation from 14 wild populations of L. graveolens growing along an edaphoclimatic gradient was evaluated. Characterization of the oils by GC-FID and GC/MS analyses allowed the identification of 70 components, which accounted for 89-99% of the total oil composition. Principal component and hierarchical cluster analyses divided the essential oils into three distinct groups with contrasting oil compositions, viz., two phenolic chemotypes, with either carvacrol (C) or thymol (T) as dominant compounds (contents >75% of the total oil composition), and a non-phenolic chemotype (S) dominated by oxygenated sesquiterpenes. While Chemotype C was associated with semi-arid climate and shallower and rockier soils, Chemotype T was found for plants growing under less arid conditions and in deeper soils. The plants showing Chemotype S were more abundant in subhumid climate. High-oil-yield individuals (>3%) were identified, which additionally presented high percentages of either carvacrol or thymol; these individuals are of interest, as they could be used as parental material for scientific and commercial breeding programs.

Background: Vanilla planifolia, a threatened species, is distributed naturally in semi-deciduous and evergreen rain forests of southeastern Mexico and parts of Central America. In the wild, it is difficult to diagnose from another sympatric Vanilla species, and individuals with reproductive structures are usually required. Questions: Can ISSR discriminate wild individuals of Vanilla planifolia from other sympatric species of the genus? Can phylogenetic analyses of ITS recover the monophyly of V. planifolia and help identify Vanilla species? Studied species: The vanilla (V. planifolia), the second-most important economically spice in the world. Study site and years of study: Plant material was collected during 2014 in the Mexican Yucatan Peninsula. Methods: We analyzed 88 wild individuals of several Vanilla species. Individuals of five species of Vanilla reported for the region were used as reference. 84 ISSR loci were analyzed using three clustering methods. A phylogenetic inference using ITS was performed. Results: ISSR markers clearly discriminate wild Vanilla planifolia, finding definite genetic structure within the species. The three clustering methods identified genetic relationships with congruent patterns. Five groups were found and they corresponded with the species studied. Phylogenetic inference of ITS sequences supported the monophyly of the Vanilla and the resulting cladograms were coherent with the clustering pattern observed in the ISSR studies. Conclusions: Both ISSR and ITS analyses are able to identify V. planifolia. Molecular data suggest the presence of V. pompona and a new species of Vanilla in the Yucatan Peninsula. Keywords: Genetic identification, molecular markers, phylogenetic analysis, vanilla, wild populations.Vanilla planifolia silvestre y sus parientes en la Península de Yucatán, México: análisis sistemáticos con ISSR e ITS Resumen Antecedentes: Vanilla planifolia es una especie amenazada que se distribuye naturalmente en las selvas tropicales perennifolias y subperennifolias del sureste de México y parte de Centroamérica. En estado silvestre, es difícil de diferenciar de otras especies simpátricas de Vanilla, y usualmente se requieren individuos con estructuras reproductivas. Preguntas: ¿Pueden los marcadores ISSR discriminar individuos silvestres de Vanilla planifolia de otras especies simpátricas de vainilla?, ¿Puede el análisis de ITS recobrar la monofilia de V. planifolia y contribuir a identificar las especies de Vanilla? Especie en estudio: Económicamente, la vainilla (Vanilla planifolia) es la segunda especia más importante en el mundo. Sitio de estudio y fecha: La colecta se realizó en 2014 en la Península de Yucatán. Métodos: Se analizaron 88 de individuos silvestres de especies de Vanilla. Se utilizaron como testigos individuos de cinco especies de vainilla reportadas para la región. 84 loci de ISSR fueron analizados usando tres métodos de agrupamiento. Se realizó una inferencia filogenética con ITS. Resultados: Los ISSR discriminaron claramente a los individuos si...

1Autor para la correspondencia: rduran@cicy.mx.Resumen: Se analizó la dinámica poblacional de genets y ramets de Mammillaria gaumeri, cactácea endémica de Yucatán con el objetivo de generar información demográfica que sustente el cambio de estatus de especie de "protección especial" a "especie en peligro de extinción" en la Norma Oficial Mexicana. Se utilizó el modelo matricial para analizar la dinámica poblacional de ocho poblaciones por un periodo de cuatro años (2004)(2005)(2006)(2007). Los resultados indican que las poblaciones están conformadas principalmente por adultos, con una densidad en el 2007 de 300 a 3,737 ind/ha. Se obtuvo un escaso porcentaje de germinación en campo y establecimiento de plántulas. La tasa de mortalidad fue mayor en las primeras categorías de tamaño, y cuando se registró alta mortalidad de adultos se debió a eventos de perturbación (saqueo ilegal, incendios). La tasa de crecimiento poblacional ( ) fluctuó de 0.6255 a 1.2629. Los valores de elasticidad indican que la permanencia de los adultos tuvo la mayor contribución a la tasa de crecimiento poblacional, por lo que la protección de estos individuos, así como la conservación del hábitat son medidas prioritarias para la permanencia de esta especie. Palabras clave: análisis de elasticidad, demografía, Mammillaria, modelos matriciales. Abstract:We analyzed the population dynamics of genets and ramets of Mammillaria gaumeri, an endemic cactus of Yucatan in order to generate demographic information that supports the change in status of species of "special protection" to "endangered species" in the Norma Oficial Mexicana. A matrix model was used to analyze the population dynamics of eight populations for a period of four years (2004)(2005)(2006)(2007). The results indicate that the populations are comprised mainly of adults, with a density in 2007 from 300 to 3,737 ind/ha. We obtained a low percentage of field germination and seedling establishment as reported for other globular cacti. The mortality rate was higher in the first categories of size, and when there was high mortality of adults due to disturbance events (illegal looting, fires). The population growth rate ( ) ranged from 0.6255 to 1.2629. Elasticity values indicated that the stasis of adults had the greatest contribution to population growth rate, so that protection of these individuals, and its habitat conservation are priority actions for the survival of this species.

The Cactaceae family in Mexico is particularly important because members of this family exhibit a high degree of endemism. Unfortunately, many species of the Cactaceae are threatened or endangered. We employed an integral projection model for studies of the population dynamics of Mammillaria gaumeri, an endemic cactus of the Yucatán characterized by a small population size. The integral projection model provides estimates of the asymptotic growth rate, stable size distribution, reproductive values, and sensitivities and elasticities of the growth rate to changes in vital rates. Nine locations of this species were studied along the Yucatan coast over a 9-year period. Individuals were classified by plant volume. Most population growth rate (k) values were below unity. The highest elasticity values corresponded to the survival of intermediate size individuals. The percentage of germination in the field was low, and consequently, fecundity values were also low. Reproductive values were observed to increase with plant volume. The stable size distribution of M. gaumeri was skewed toward small individuals. For all years, the kernel showed that individual survival determined the population growth rate.