Abstract Species of Opuntia (prickly pears), widely propagated for human use, are present in many agroforestry systems. Like other perennials, they are subject to environmental pressures that influence their reproductive ecology and reproductive output. Here, we studied floral biology, breeding system, and flower-bee interactions of Opuntia atropes, which is subject to management, to better understand its reproductive ecology. We documented floral phenology, morphology, and mating system by observing live flowers, measuring fixed flowers, and performing pollination treatments. We recorded frequency, behavior, and floral visitors’ handling time to determine the most effective pollinator. Opuntia atropes has large, herkogamous flowers and high P/O ratios. These traits promote outcrossing, which was supported by the results of pollination treatments. Fruit weight and seed set exhibited moderate pollen limitation. Floral visitors comprised nine bee species. Diadasia sp. was the most effective pollinator according to frequency and behavior. Opuntia atropes shows preferential outcrossing through pollination by a specialist bee despite being in a modified habitat. Pollen limitation and variation in reproductive success may lead to mating system evolution in O. atropes. The observed bee diversity suggests that O. atropes is an important source of floral resources in the dry season in semi-arid environments under moderate human disturbance. prickly pears, pears , pears) use systems perennials output Here biology flowerbee flower management phenology morphology treatments behavior large PO P O ratios species sp habitat semiarid semi arid disturbance

Abstract The domestication of plants and animals allows the study of different evolutionary processes, including selection, adaptation and speciation. Here we describe recent advances in the study of pumpkins and squashes, which constitute the genus Cucurbita (Cucurbitaceae), being a group of herbaceous plants from the Americas that include between 12 and 15 species. Cucurbita has had six domestication events, four of them occurred in Mexico. This is a relatively recent genus that originated in North America 16 million years ago and its cultivated species maintain high levels of genetic variation. Cucurbita pepo is the species with the highest genetic diversity, diversity associated to two independent domestications, one in Northern Mexico and the other in Southern United States. In another species, Cucurbita argyrosperma, the populations from Yucatan Peninsula represents a genetic pool differentiated from the rest of the species. The study of the genome of C. argyrosperma and related taxa has revealed the regions of its genome associated with domestication. The populations of the species of this genus represent a source of important genetic resources in the face of climate change and constitute a good system for the study of domestication and of different evolutionary processes.

Resumen La domesticación de plantas y animales permite estudiar diferentes procesos evolutivos, como la selección, adaptación y especiación. En este artículo se describen avances recientes en el estudio de las calabazas, las cuales constituyen el género Cucurbita (Cucurbitaceae) siendo un grupo de plantas herbáceas americanas que incluyen entre 12 y 15 especies. Cucurbita ha tenido seis eventos de domesticación, de los cuales cuatro sucedieron en México. Este es un género relativamente reciente, que surgió en Norte América hace 16 millones de años y sus especies cultivadas mantienen una alta variación genética; Cucurbita pepo es la especie que presenta mayor variación genética,variación asociada a dos domesticaciones independientes, una en el norte de México, y otra en el Sureste de los Estados Unidos. En otra especie, Cucurbita argyrosperma, sus poblaciones de la Península de Yucatán, representan una poza genética diferenciada del resto de la especie. El estudio del genoma de C. argyrosperma y taxa cercanos ha revelado las regiones de su genoma asociadas a la domesticación. Las poblaciones de las especies de este género representan una fuente de importantes recursos genéticos frente al cambio climático y constituyen un buen sistema para el estudio de la domesticación y de diferentes procesos evolutivos.

Wild Nicotiana species are reservoir of genes for several pests, besides other genes for important phytochemical and quality traits, which are not present in cultivated varieties. The application of Random Amplified Polymorphic DNA (RAPD) analysis to determine the degree of genetic variation among ten wild Nicotiana species is herein presented. Four of the ten primers used in RAPD analysis, produced amplification products that were too faint to score or could not be consistently reproduced and six primers yielded a total of 117 bands, all of them polymorphic. All the bands were scored from the comparison of amplification, with an average of 19.5 bands scored per primer. The highest level of polymorphism among the species was observed for Nicotiana velutina Wheelen and Nicotiana glutinosa L., with 35.89% and 32.47% respectively, both from subgenus Petunioides. In contrast, the lowest level of polymorphism (18,80%) was observed for Nicotiana knightiana Goodsp, subgenus Rustica. The clustering pattern matched with the traditional classification of Nicotiana species. In nine of the ten wild Nicotiana species evaluated, all the primers generated at least two specifics bands. The total of the 32 species-specific markers identified in the present study will be useful in the genetic breeding programs.

Las especies silvestres del género Nicotiana son reservorios de genes de resistencia a plagas, así como para rasgos cualitativos y fitoquímicos importantes, los cuales no están presentes en las variedades cultivadas. El objetivo de trabajo fue caracterizar la variabilidad genética de 10 especies silvestres del género Nicotiana mediante el uso de marcadores RAPD (Fragmentos Polimórficos de ADN Amplificados al Azar). De los diez cebadores usados en el ensayo RAPD, cuatro de ellos produjeron productos de amplificación que resultaron apenas visibles para ser evaluados o no fueron consistentemente reproducibles y seis cebadores produjeron un total de 117 bandas, 100% polimórficas. Todas las bandas se evaluaron para la comparación de la amplificación, para un promedio de 19,5 bandas por cebador. El mayor nivel de polimorfismo entre las especies se observó en Nicotiana velutina Wheelen y Nicotiana glutinosa L. con 35,89% y 32,47% respectivamente, ambas del subgénero Petunioides. En contraste, el menor porcentaje de polimorfismo se observó en la especie Nicotiana knightiana Goodsp (18,80%), perteneciente al subgénero Rustica. El patrón obtenido en el dendrograma coincide con la clasificación tradicional de las especies del género Nicotiana. En nueve, de las 10 especies silvestres del género Nicotiana evaluadas, todos los cebadores generaron al menos dos bandas específicas. El total de los 32 marcadores específicos de cada especie encontrados en el presente estudio podría resultar de gran utilidad en los programas de mejoramiento genético.