Distribución geográfica de los parientes silvestres del acervo genético mesoamericano del frijol lima (Phaseolus lunatus L.) en México

The Mesoamerican gene pool of wild Lima bean (Phaseolus lunatus L., Fabaceae) is an important source of genes for genetic improvement of the species. Is widely distributed from northern Mexico to northern Argentina. Reports in Mexico indicate that this gene pool is distributed from Sinaloa to Chiapas on the Pacific Coast and southern Tamaulipas to the Yucatan Peninsula on the Coast of Gulf of Mexico, as well as, in the Isthmus of Tehuantepec. However, despite the knowledge we have about the distribution of this gene pool, in Mexico there are still collecting gaps and unexplored regions. The objective of this study was to collect wild populations of Lima bean in Mexico to know its current distribution and establish management and conservation strategies. To do this, we collected within the natural distribution range of the Mesoamerican gene pool of Lima bean in Mexico, with the passport data was designed a geographical distribution map and assessed the conservation status of populations. Results indicated that wild populations of Lima bean have a wide geographical distribution localized mainly in tropical deciduous forest and semideciduous and elevations from zero to 2, 292 meters. In most wild population collected a low conservation status was observed, in consequence was proposed the development of strategies for in situ and ex situ conservation for wild populations with higher degree of erosion.El estudio de la fenología de las especies permite entender y predecir épocas de floración y fructificación útiles en el manejo de árboles tropicales caducifolios. La presente investigación se realizó en tres plantaciones de Cordia dodecandra (P1, P2 y P3) establecidas en el año 2002 en Xmatkuil, Yucatán, que se han manejado de diferente manera: poda, riego y deshierbe (P1); deshierbe (P2) y sin manejo (P3). Los objetivos de este trabajo fueron evaluar la fenología, la producción y calidad de los frutos de tres plantaciones. La fenología se determinó una vez al mes, utilizando el método de Fournier. La producción se evaluó cosechando y contabilizando la totalidad de frutos de todos los árboles de cada plantación, y la calidad del fruto, mediante el peso y medidas del largo y ancho de una muestra (n=20) de cada plantación. Además, se obtuvo el porcentaje de humedad de los mismos poniéndolos en una secadora a 60° C. Los resultados mostraron que P1 presentó hojas en porcentajes del 100% en septiembre 2011, en octubre disminuyó y el porcentaje de hojas fue de 25% y posteriormente en el periodo de noviembre 2011-agosto 2012 nuevamente hubo 100% de hojas. P2 y P3, perdieron sus hojas durante el periodo diciembre-marzo. Respecto a la floración, P1 presentó flores en porcentajes del 25% durante casi todo el año, a excepción de junio y julio, en los que no se registró la presencia de ninguna estructura floral; el pico máximo se observó en marzo. Las otras dos plantaciones sólo tuvieron floración durante la época de sequía (diciembre-mayo). En el mes de febrero, P2 presentó un pico máximo y P3 en marzo. La presencia de frutos en P1 se observó en octubre, noviembre y enero, incrementándose hasta obtener un pico máximo en mayo. En P2 la fructificación se observó de enero-junio y presentó un pico máximo en marzo, y en P3, de febrero-mayo con pico máximo en mayo. La mayor producción y calidad de frutos se registró en P1 presentando diferencias significativas

It takes two to tango: self incompatibility in the bromeliad Tillandsia streptophylla (Bromeliaceae) in Mexico

Floral phenology and breeding system of Tillandsia streptophylla (Bromeliaceae) were studied in a low inundated forest in Yucatan, Mexico. During the flowering season, from March to August, terminal scapose 1-branched, paniculate inflorescences are produced with one flower per branch opening per day, over a period of 11-29 days. Flowers are tubular, light violet, with the stigma placed below the anthers, both protruding above the corolla. Flowers are protandrous, with anthers releasing pollen from 0500 hours and stigma becoming receptive around 0900 hours. Controlled experimental crosses suggest that Tillandsia streptophylla is self incompatible and therefore, pollinator-dependent. Rev. Biol. Trop. 57 (3): 761-770. Epub 2009 September 30.Estudiamos la fenología floral y el sistema de cruzamiento de la bromelia Tillandsia streptophylla (Bromeliaceae) en una selva baja inundable en Yucatán, México. Durante la estación de floración (marzo a agosto), las plantas producen una inflorescencia terminal, escaposa, paniculada, 1-dividida, con una flor abriendo por rama por día para un período de floración de 11-29 días por inflorescencia. Las flores son tubulares, de corola violeta claro, con el estigma y anteras exertos, pero las anteras más largas que el estigma en antesis. Las flores son protandras, con las anteras liberando el polen desde las 0500 horas y la receptividad del estigma comenzando a las 0900 horas. Los cruces experimentales controlados sugieren que Tillansdia streptophylla es auto incompatible y por ende, dependiente de los polinizadores

Reproductive biology of Hechtia schottii, a dioecious Bromeliaceae, in Mexico

Hechtia schottii is a terrestrial, rosetofilous, dioecious, polycarpic succulent herb, that grows mainly in shrubby associations, and less frequently, in secondary low caducifolious forests, both on calcareous soils or limestone outcrops in Yucatan and Campeche States, Mexico. We studied phenology, floral and pollination biology, and breeding system at Calcehtok, Yucatan, during two flowering seasons. Plants bloom mainly during the dry season (November-April) and disperse seeds during the rainy season (May-October). Both floral morphs have diurnal anthesis; pollen is removed ca. 1 h after anthesis starts and both floral morphs are visited by several insect species, especially bees, but results suggest that the introduced honey bee, Apis mellifera, is the pollinator. Controlled crossings show that the species is functionally dioecious and requires to be serviced by pollinators based on fruit setting only in unassisted cross pollination crosses

It takes two to tango: self incompatibility in the bromeliad Tillandsia streptophylla (Bromeliaceae) in Mexico

Floral phenology and breeding system of Tillandsia streptophylla (Bromeliaceae) were studied in a low inundated forest in Yucatan, Mexico. During the flowering season, from March to August, terminal scapose 1-branched, paniculate inflorescences are produced with one flower per branch opening per day, over a period of 11-29 days. Flowers are tubular, light violet, with the stigma placed below the anthers, both protruding above the corolla. Flowers are protandrous, with anthers releasing pollen from 0500 hours and stigma becoming receptive around 0900 hours. Controlled experimental crosses suggest that Tillandsia streptophylla is self incompatible and therefore, pollinator-dependent

Reproductive biology of Hechtia schottii, a dioecious Bromeliaceae, in Mexico

Hechtia schottii is a terrestrial, rosetofilous, dioecious, polycarpic succulent herb, that grows mainly in shrubby associations, and less frequently, in secondary low caducifolious forests, both on calcareous soils or limestone outcrops in Yucatan and Campeche States, Mexico. We studied phenology, floral and pollination biology, and breeding system at Calcehtok, Yucatan, during two flowering seasons. Plants bloom mainly during the dry season (November-April) and disperse seeds during the rainy season (May-October). Both floral morphs have diurnal anthesis; pollen is removed ca. 1 h after anthesis starts and both floral morphs are visited by several insect species, especially bees, but results suggest that the introduced honey bee, Apis mellifera, is the pollinator. Controlled crossings show that the species is functionally dioecious and requires to be serviced by pollinators based on fruit setting only in unassisted cross pollination crosses. Rev. Biol. Trop. 56 (1): 279-289. Epub 2008 March 31.Hechtia schottii es una hierba terrestre, suculenta, rosetófila, dioica y policárpica, que crece en asociaciones arbustivas y selva baja caducifolia secundaria, ambos en suelos calcáreos o limosos. Estudiamos la fenología, la biología floral, reproductiva y de la polinización en una población en Calcehtok, Yucatán, México, durante dos estaciones de floración. Las plantas florecen principalmente en la época de secas (noviembre-abril) y la dispersión de semillas es durante la estación de lluvias (mayo-octubre). Ambas formas (morphs) florales tienen antesis diurna; el polen es removido ca. 1 h después del comienzo de la antesis y ambas formas florales son visitadas por varias especies de insectos, especialmente abejas, pero los resultados sugieren que la abeja introducida, Apis mellifera, es el polinizador. Cruces controlados muestran que la especie es funcionalmente dioica y que requiere de un polinizador, ya que solo produce frutos por polinización no asistida entre formas

Distribución geográfica de los parientes silvestres del acervo genético mesoamericano del frijol lima (Phaseolus lunatus L.) en México

Abstract: The Mesoamerican gene pool of wild lima bean (Phaseolus lunatus L., Fabaceae) is an important source of genes for genetic improvement of the species. Is widely distributed from northern Mexico to northern Argentina. Reports in Mexico indicate that this gene pool is distributed from Sinaloa to Chiapas on the Pacific Coast and southern Tamaulipas to the Yucatan Peninsula on the Coast of Gulf of Mexico, as well as, in the Isthmus of Tehuantepec. However, despite the knowledge we have about the distribution of this gene pool, in Mexico there are still collecting gaps and unexplored regions. The objective of this study was to collect wild populations of lima bean in Mexico to know its current distribution and establish management and conservation strategies. To do this, we collected within the natural distribution range of the Mesoamerican gene pool of lima bean in Mexico, with the passport data was designed a geographical distribution map and assessed the conservation status of populations. Results indicated that wild populations of lima bean have a wide geographical distribution localized mainly in tropical deciduous forest and semideciduous and elevations from zero to 2 292 meters. In most wild population collected a low conservation status was observed, in consequence was proposed the development of strategies for in situ and ex situ conservation for wild populations with higher degree of erosion.Resumen: El acervo genético mesoamericano del frijol lima silvestre (Phaseolus lunatus L., Fabaceae) representa una fuente importante de genes para el mejoramiento genético de la especie. Presenta una amplia distribución geográfica que abarca del norte de México al norte de Argentina. En México los reportes muestran que este acervo se distribuye de Sinaloa hasta la región de Chiapas, por la costa del Pacífico y del sur de Tamaulipas hasta la Península de Yucatán por la Costa del Golfo de México, así como también en la región del Istmo de Tehuantepec. Sin embargo, a pesar del conocimiento que se tiene sobre la distribución de este acervo, en México aún existen regiones con vacíos de colecta para P. lunatus. El objetivo del presente trabajo consistió en realizar colectas de poblaciones silvestres del frijol lima en México, para conocer su distribución actual y establecer estrategias de manejo y conservación. Para ello, se realizaron colectas dentro del área de distribución natural del acervo genético mesoamericano del frijol lima en México, se diseño un mapa de distribución geográfica con los datos de pasaporte y se analizó el estado de conservación de las poblaciones. Los resultados demostraron que las poblaciones silvestres del frijol lima, presentan una amplia distribución geográfica localizándose principalmente en zonas de selva tropical caducifolia y subcaducifolia con altitudes de cero a 2 292 metros. Se observó un bajo estado de conservación en la mayoría de las poblaciones silvestres colectadas, en consecuencia, se propuso el desarrollo de estrategias de conservación in situ y ex situ para las poblaciones silvestres con mayor grado de erosión

Multiple Factors Influence Seasonal and Interannual Litterfall Production in a Tropical Dry Forest in Mexico

Litterfall production plays a fundamental role in the dynamics and function of tropical forest ecosystems, as it supplies 70–80% of nutrients entering the soil. This process varies annually and seasonally, depending on multiple environmental factors. However, few studies spanning several years have addressed the combined effect of climate variables, successional age, topography, and vegetation structure in tropical dry forests. In this study, we evaluated monthly, seasonal, and annual litterfall production over a five-year period in semideciduous dry forests of different successional ages growing on contrasting topographic conditions (sloping or flat terrain) in Yucatan, Mexico. Its relationship with climate and vegetation structural variables were also analyzed using multiple linear regression and generalized linear models. Litterfall was measured monthly in 12 litterfall traps of 0.5 m2 in three sampling clusters (sets of four 400 m2 sampling plots) established in forests of five successional age classes, 3–5, 10–17, 18–25, 60–79, and >80 years (in the latter two classes either on slopping or on flat terrain), for a total of 15 sampling clusters and 180 litterfall traps. Litterfall production varied between years (negatively correlated with precipitation), seasons (positively correlated with wind speed and maximum temperature), and months (negatively correlated with relative humidity) and was higher in flat than in sloping sites. Litterfall production also increased with successional age until 18–25 years after abandonment, when it attained values similar to those of mature forests. It was positively correlated with the aboveground biomass of deciduous species but negatively correlated with the basal area of evergreen species. Our results show a rapid recovery of litterfall production with successional age of these forests, which may increase with climate changes such as less precipitation, higher temperatures, and higher incidence of hurricanes

Landscape-scale forest cover drives the predictability of forest regeneration across the Neotropics

Abandonment of agricultural lands promotes the global expansion of secondary forests, which are critical for preserving biodiversity and ecosystem functions and services. Such roles largely depend, however, on two essential successional attributes, trajectory and recovery rate, which are expected to depend on landscape-scale forest cover in nonlinear ways. Using a multi-scale approach and a large vegetation dataset (843 plots, 3511 tree species) from 22 secondary forest chronosequences distributed across the Neotropics, we show that successional trajectories of woody plant species richness, stem density and basal area are less predictable in landscapes (4 km radius) with intermediate (40–60%) forest cover than in landscapes with high (greater than 60%) forest cover. This supports theory suggesting that high spatial and environmental heterogeneity in intermediately deforested landscapes can increase the variation of key ecological factors for forest recovery (e.g. seed dispersal and seedling recruitment), increasing the uncertainty of successional trajectories. Regarding the recovery rate, only species richness is positively related to forest cover in relatively small (1 km radius) landscapes. These findings highlight the importance of using a spatially explicit landscape approach in restoration initiatives and suggest that these initiatives can be more effective in more forested landscapes, especially if implemented across spatial extents of 1–4 km radius