ABSTRACT
AbstractThe Ceratozamianorstogii complex from Southern Mexico is made up of four closely related taxa and occurs in similar habitats (Quercus forest). All have linear-lanceolate leaflets with great similarity between them, especially in juvenile stages, but differentiate with age. There has been debate regarding delimitation of species due to character loss in herbarium specimens. The aim of this study was to determine the genetic variation, and to measure genetic similarity between the four taxa. We studied populations in Cintalapa (Chiapas) for C. alvarezii and C. norstogii; the Sierra Atravesada (Oaxaca) for C. chimalapensis, and Villa Flores (Chiapas) for C. mirandae. One population for each taxon was sampled (only one population is known for C. alvarezii) 11-15 randomly chosen adult individuals were sampled. Twenty-eight primers were tested of which five were polymorphic using the RAPD'S technique. The data were analyzed using Bayesian methods. Results revealed low genetic diversity, and a differentiation was found between species, suggesting a recent divergence. A previous morphological and anatomical study on the complex has found the taxa to be distinct. However, the results of this study have shown that the C. norstogii species complex is in a divergence process, probably through genetic drift and founder effects. Rev. Biol. Trop. 65 (1): 305-319. Epub 2017 March 01.
ResumenLos cuatro taxa que componen el complejo Ceratozamia norstogii de especies en el sur de México están estrechamente relacionados y se dan en hábitats similares (bosque de Quercus). Todos tienen folíolos linear-lanceolados con gran similitud entre ellos, sobre todo en las etapas juveniles, pero se diferencian con la edad. Ha habido un debate en relación con la delimitación de especies debido a la pérdida de caracteres en especímenes de herbario. Los objetivos de este estudio son determinar la variación genética y medir la similitud genética entre los cuatro taxones en el complejo. Las poblaciones estudiadas están en; Cintalapa, Chiapas para C. alvarezii y C. norstogii, la Sierra Atravesada, Oaxaca para C. chimalapensis y Villa Flores, Chiapas para C. mirandae. Se tomaron muestras de una población de cada taxón (sólo una población es conocida para C. alvarezii) 11-15 individuos adultos elegidos al azar fueron muestreados. Veintiocho primers fueron probados, de los cuales cinco fueron polimórficos mediante la técnica RAPD's. Los datos fueron analizados utilizando métodos bayesianos. Los resultados revelaron baja diversidad genética y la diferenciación encontrada entre las especies sugiere una divergencia reciente. Un estudio morfológico y anatómico anterior en el complejo encontró que los taxa son distintos. Sin embargo, los resultados del presente estudio han demostrado que el complejo C. norstogii aun se encuentra en un proceso de divergencia, probablemente a través de deriva genética y efectos de fundador.
Subject(s)
Genetic Variation , Zamiaceae/genetics , Plant Dispersal , Reference Values , Species Specificity , Genetic Markers , Bayes Theorem , Random Amplified Polymorphic DNA Technique/methods , Biodiversity , MexicoABSTRACT
Mexico has the second largest cycad diversity in the world, and the Sierra Madre Oriental (SMO) is one of the richest biogeographic regions for these plants. Despite there is a general Cycad National Program in the country, there are no state-level cycad conservation strategies or programs. Thus the aim of this study was to propose a cycad conservation strategy for the state of Hidalgo, which is located in the Southern part of the SMO. For this, a cycad species inventory was made in the state, for which three methods were used: review of published literature; consultation in the main Mexican herbaria to verify botanical specimens; and exhaustive field research to compare findings with previously reported species and to recognize new records at the county and state level. The proposed research work strategy combined the following elements: prioritize the county and local areas with greatest cycad species richness; prioritize the species least resistant to environmental change and/or having restricted geographic distribution; and to consider the main uses of these plants by local residents. The results showed that Hidalgo has three genera and eight species of cycads: Ceratozamia fuscoviridis, C. latifolia, C. mexicana, C. sabatoi, Dioon edule, Zamia fischeri, Z. loddigesii and Z. vazquezii, all of which are considered by the International Union for Conservation of Nature (IUCN). This study added two new species records for Hidalgo and 21 at the county level. The species are distributed in 26 counties, of which Chapulhuacán and Pisaflores are notable for their high species richness. Hidalgo has the fourth-greatest cycad species richness among Mexican states, although its area accounts for only 1.07% of the country. The state’s diversity is greater than in other states with larger area, and even than in some other entire countries in Mesoamerica. The presented state cycad conservation strategy proposes that a total of some 11 325ha to be conserved in nine zones, including different vegetation types, distributed in seven counties. The strategy involves a mixed scheme that incorporates conservation in Protected Natural Areas (ANP), Small Farmer Reserves (Reservas Campesinas) and Environmental Management Units (UMA in Spanish). This proposal will be useful for government agencies to take into account in the process of designating land use for the Cloud Forest Biological Corridor (CBBMM in Spanish), a ANP in creation. The state of Hidalgo urgently needs a detailed analysis of trends in changes in vegetation cover and land use, and demographic studies of the cycads. It is recommended that the implementation phase of this state strategy be carried out jointly with local communities, academia, and state and federal agencies responsible for biodiversity conservation.
México es el segundo país con mayor diversidad de cícadas en el mundo. En él, la Sierra Madre Oriental (SMO) es una de las regiones biogeográficas con mayor riqueza de estas plantas. El objetivo de este estudio fue plantear la estrategia de conservación de cícadas para el estado de Hidalgo, ubicado en la parte sur de la SMO; para esto se revisó la literatura científica, se consultaron los principales herbarios de México y se hicieron recorridos de campo. Los resultados muestran que Hidalgo alberga tres géneros y ocho especies: Ceratozamia fuscoviridis, C. latifolia, C. mexicana, C. sabatoi, Dioon edule, Zamia fischeri, Z. loddigesii, Z. vazquezii, posicionándose en el cuarto lugar nacional en riqueza de cícadas. Las especies se distribuyen en 26 municipios. Se encontró que la diversidad de cícadas es mayor a la de otras entidades con mayor superficie e incluso a la de algunos países de Centroamérica. La estrategia estatal de conservación de cícadas aquí desarrollada propone conservar cerca de 11 325ha, distribuidas en siete municipios, bajo un esquema mixto de conservación. Esta propuesta será útil para que las instancias gubernamentales establezcan nuevas ANP’s en la región biogeográfica de la SMO.
Subject(s)
Biodiversity , Conservation of Natural Resources/methods , Cycas/classification , MexicoABSTRACT
A partir de explantes de embriones cigóticos y megagametofitos fueron inducidos cultivos organogénicos de Dioon merolae del estado de Chiapas (México), cícada en peligro de extinción. El medio de inducción Litz consistió en los macronutrientes del medio B5, los micronutrientes del medio MS y los compuestos orgánicos glutamina (400mg·l-1) arginina (100mg·l-1), asparagina (100mg·l-1), sacarosa (60g·l-1), gellan-gum (4g), y suplementado con 0; 0,45; 2,26; 4,52 y 9,05μM αcido 2,4-diclorofenoxiacético (2,4-D), y 0; 2,32; 4,60; 9,30 y 13,90μM kinetina (K), con un arreglo de 5´5 con un diseño de bloque seleccionado al azar. Los cultivos fueron mantenidos en oscuridad a 25°C y el callo fue subcultivado en medio fresco cada cuatro semanas. La iniciación del callo ocurrió en un amplio rango de combinaciones de reguladores de crecimiento en explantes de megagametofito. El callo en explantes de embriones cigóticos se formó en pocas combinaciones. La formación de brotes adventicios ocurrió solo en callos que provenían de combinaciones con K y 2,4-D. A través del análisis histológico de secciones longitudinales de embriones cigóticos se detectaron células meristemáticas apicales de brote y raíz, y en megagametofitos la formación de elementos de conducción similares a traqueidas y raíces coraloides. Esta técnica presenta gran potencial para la preservación de especies de cícadas en peligro de extinción.
Organogenic cultures were induced from zygotic embryo and megagametophyte explants of the Chiapas State (México) endangered cycad species, Dioon merolae. The Litz induction medium consisted of B5 major salts, MS medium minor salts and the organics glutamine (400mg·l-1), arginine (100mg·l-1), asparagines (100mg·l-1), sucrose (60g·l-1), gellan gum (4g), and supplemented with 0, 0.45, 2.26, 4.52 and 9.05μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0, 2.32, 4.60, 9.30, 13.90μM kinetin (K), arranged as a 5´5 factorial in a randomized block design. Cultures were maintained in darkness at 25°C, and callus was subcultured onto fresh medium at 4 week intervals. Callus initiation occurred on a wide range of plant growth regulators (PGR) combinations from megagametophyte explants. In comparison, callus initiation from explanted zygotic embryos occurred on few PGR combinations. Adventitious shoot induction occurred from callus on formulations with K and 2,4-D. Through the histological analysis of longitudinal sections of zygotic embryos were detected apical meristematic cells of the shoot and root and in megagametophytes the formation of elements similar to tracheids and coralloid roots. This technique has a great potential for preservation of the highly endangered cycads.
A partir de explantes de embriões zigóticos e megagametofitos foram induzidos cultivos organogênicos de Dioon merolae do estado de Chiapas (México), Cicas em perigo de extinção. O meio de indução Litz consistiu nos macronutrientes do meio B5, os micronutrientes do meio MS e os compostos orgânicos glutamina (400mg·l-1) arginina (100mg·l-1), asparagina (100mg·l-1), sacarose (60g·l-1), goma gelana (4g), e suplementado com 0; 0,45; 2,26; 4,52 e 9,05μM αcido 2,4-diclorofenoxiacético (2,4-D), e 0; 2,32; 4,60; 9,30 e 13,90μM kinetina (K), com um arranjo de 5×5 com um desenho de bloco selecionado aleatoriamente. Os cultivos foram mantidos no escuro a 25°C e o calo foi subcultivado, em meio fresco, cada quatro semanas. A iniciação do calo ocorreu em uma ampla faixa de combinações de reguladores de crescimento em explantes de megagametofito. O calo em explantes de embriões zigóticos se formou em poucas combinações. A formação de brotos adventícios ocorreu somente em calos que provinham de combinações com K e 2,4-D. Através da análise histológica de secções longitudinais de embriões zigóticos se detectaram células meristemáticas apicais de broto e raiz, e em megagametófitos a formação de elementos de condução similares a traqueídes e raízes coralóides. Esta técnica apresenta grande potencial para a preservação de espécies de Cicas em perigo de extinção.