bluuebunny/crossref_metadata_2025 huggingface dataset:
Diferentes tasas evolutivas entre grupos de angiospermas. Eudicotiledóneas
Authors: Magañón-Puebla Susana
Published: January 2019

Applying analytical models to two clades, eudicotyledons and paleoherbs, three filogeny models were explored and analyzed with parameters that vary from low extinction rates to high speciation rates. Filogeny Model I suggest that the probability ty of obtaining a difference in species distribution, between the two sister clades, as the observed, or higher, varies between 15.2% with high speciation rates and 16.7% with low extinction rates. In Filogeny Model II the probability of obtaining a species distribution similar to the observed one or higher, varies between 15.7% with high speciation rates to 17.4% with low extinction rates. In contrast, probability of obtaining a species distribution like the observed or higher in Filogeny Model III varies from 2.5% with high speciation rates to 2.8% with low extinction rates. Accordingly with the tree Models, the probability of obtaining a numerical difference at the species level between eudicotyledons and its sister group are low. However, results suggest the eudicotyledons are characterize by higher evolutionary rates (speciation-extinction) compared with other groups of angiosperms.
Especies del género Mimosa (Leguminosae) presentes en México
Authors: Grether Rosaura , Camargo-Ricalde Sara Lucía , Martínez-Bernal Angélica
Published: January 2019

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Anatomía del tallo y de la raíz de dos especies de Wilcoxia Britton & Rose (Cactaceae) del noreste de México
Authors: Loza-Cornejo Sofía , Terrazas Teresa
Published: January 2019

Se estudia la anatomía del tallo y la raíz de dos especies de Wilcoxia distribuidas en el noreste de México con la finalidad de contribuir al conocimiento de las cactáceas, cotejar la ausencia de radios en su xilema secundario y comparar su anatomía con la de otros miembros de Cactoideae. Los resultados muestran que las especies de Wilcoxia presentan hipodermis uniestratificada, peridermis unidireccional, clorénquima en empalizada, ausencia de fibras en el floema y de radios en el xilema secundario. Se considera que la ausencia de radios probablemente fue un factor importante en la evolución del cámbium vascular de estas especies. Las especies difieren en algunos caracteres cuantitativos y en el tipo porosidad. En las raíces tuberosas de Wilcoxia el tejido vascular es escaso y restringido a hileras radiales, mientras que el tejido de almacenamiento se desarrolla en corteza primaria y parénquima asociado al xi lema secundario. Los estudios del desarrollo de la raíz tuberosa, podrían contribuir al entendimiento de la diversidad anatómica encontrada en Cactaceae.
Embriología de Erythroxylum havanense Jacq. (Erythroxylaceae)
Authors: Vázquez-Santana Sonia , Domínguez César A. , Márquez-Guzmán Judith
Published: January 2019

We studied the development of reproductive structures in pin and thrum morphs of Erythroxylum havanense. The young anther wall consists of an epidermis, endothecium , 1-3 middle layers anda binucleate secretory tapetum. The mature anther wall has only two layers: epidermis and endothecium. Microspore tetrads are tetrahedral or isobilateral. Mature pollen grains are tricolporate, bicellular and contain starch grains. Exine sculpturing is verrugate in thrum pollen and reticulate in pin pollen. The ovule is sessile, pendulous, anatropous, bitegmic and crassinucellate. The embryo sac is heptacellular. An endothelium is differentiated. The endosperm development is nuclear, and the basal part of the nucellus persists during early endosperm development. Both integuments form the seed coat.
Observaciones sobre un sistema de producción agrícola en el Pico de Orizaba, Veracruz, México
Authors: Ávila-Bello Carlos H.
Published: January 2019

The fir (Abies hickelii and Abies religiosa) forest in Veracruz is distributed in deep soils, humid mist and protected ravins. Established near these forests, human communities obtain different products. Understand how, why and when these human communities use the natural resources, can give us alternatives for their sustainable use. In the traditional production system of the fir forest in the Pico de Orizaba, the family represents the nucleus of the system and there are six main subsystems: agriculture, forest, home garden, sale of task, animal husbandry and hunting. The present study shows preliminary observations that will contribute to obtain new lines of research. Field trips, informal interviews with peasants and periods of three to four days of stay in the community provided data for this study.
Phylogenetic analysis of large molecular data sets
Authors: Soltis Pamela S. , Soltis Douglas E.
Published: January 2019

Technological advances in molecular biology have greatly increased the speed and efficiency of DNA sequencing, making it possible to construct large molecular data sets for phylogeny reconstruction relatively quickly. Despite their potential for improving our understanding of phylogeny, these large data sets also provide many challenges. In this paper, we discuss several of these challenges, including 1) the failure of a search to find the most parsimonious trees (the local optimum) in a reasonable amount of time, 2) the difference between a local optimum and the global optimum, and 3) the existence of multiple classes (islands) of most parsimonious trees. We also discuss possible strategies to improve the' likelihood of finding the most parsimonious tree(s) and present two examples from our work on angiosperm phylogeny. We conclude with a discussion of two alternatives to analyses of entire large data sets, the exemplar approach and compartmentalization, and suggest that additional consideration must be given to issues of data analysis for large data sets, whether morphological or molecular.
Marcadores moleculares
Authors: Simpson June
Published: January 2019

Molecular markers are becoming essential tools in many areas of biology including bio-medicine, breeding, forensics and diversity analysis. In addition they are also being exploited to locate and isolate genes of interest. A variety of DNA based molecular marker techniques are now available. Individual techniques employ different methods used routinely in molecular biology and different kinds of markers are distinguished by their capacity to detect polymorphism at one or many loci and whether they are dominant or co-dominant markers. The choice of marker system will depend on individual laboratory facilities and the applications of interest to each researcher.
Amplified fragment length polymorphisms (AFLP's)
Authors: Simpson June
Published: January 2019

AFLP is a combination restriction fragment/PCR molecular marker technique which detects polymorphisms due to changes at or in the vicinity of restriction enzyme sites. The technique detects multiple polymorphic loci throughout the genome and may be used for fingerprinting and mapping purposes. The main advantages of the method are the consistency and reliability of the technique due to stringent PCR conditions and the ability to rapidly detect many polymorphic loci.
El uso de secuencias génicas para estudios taxonómicos
Authors: González Dolores
Published: January 2019

During the last years, the use of molecular characters for taxonomic research has increased notably. Characters most commonly used come from restriction enzymes and sequencing of genes or particular DNA regions. Sequences present potential advantages over other molecular characters. This paper describes sampling procedures to detect DNA variation through sequencing. Among procedures for DNA sequencing, enzymatic methods are of generalized application, and the tendency is toward the use of non-radioactive markers and automated sequencing. A brief introduction to the different stages of cladistic analysis is also included, especially those required for DNA sequences. A revision of genes used in systematics is provided. The most common are the nuclear, mitochondrial and chloroplast ribosomal RNA genes, and the rbcL from chloroplast. Other genes under investigation are the globins and the alcohol dehydrogenase (from the nuclear genome), the cytochrome b and the transfer RNAs (from the mitochondrial genome), and the "matK" and the "rpo" (from the chloroplast genome).
La región de los ITS del ADN ribosomal del núcleo (nrADN), fuente de caracteres moleculares en la sistemática de las gimnospermas
Authors: Quijada Adrián , Méndez-Cárdenas Guadalupe , Hernández-Baños Blanca , Álvarez-Buylla Elena
Published: January 2019

The ITS region of gymnosperm plants has shown to be longer than the typical angiosperm ITS and shows considerable length variation. The larger size relative to the ITS in angiosperms offers more characters for phylogenetic reconstruction, which make this marker suitable for inference at different taxonomic levels. Unlike chloroplast DNA (cpDNA), ITS data can provide direct evidence of interspecific hibridization. This permits the use of the ITS to obtain measurements of introgression rates among populations and to detect events of reticulate evolution. Infraspecific ITS variation in the genus Pinus has been reported, which can compromises the inference of interspecific relationships. This potential must be taken into account in phylogenetic inference of gymnosperms.
Estudio de hongos micorrizógenos arbusculares bajo árboles remanentes en un pastizal tropical
Authors: Ramírez-Gerardo Marithza , Álvarez-Sánchez Javier , Guadarrama Chávez Patricia , Sánchez-Gallén Irene
Published: January 2019

The remnant trees in casttle have a significant ecological importance because they alter the microhabitat and also affect biological interactions. Ali these factors improve mycorrhizal fungi establishment and forest vegetation species proliferation. The objective of this study was to determine space-temporal variation of the morphospecies of arbuscular mycorrhiza and their spores number under remnant trees. This study was carried out in a casttle, in the northern edge of the Biology Station of "Los Tuxtlas", Veracruz, Mexico. Four isolated trees (Ampelocera hottlei, Poulsenia armata and Ficus sp.) were chosen. Soil samples were collected under each tree cover during dry, rainy and "nortes" seasons. Thirteen arbuscular mycorrh izal species of the Glomaceae, Acaulosporaceae and Gigasporaceae families were observed. The number of spores among climatic seasons was significant different, the highest value was presented in "nortes" season and the lowest occurred in the dry season. There were no significant differences among isolated tree species, this could imply that the remnant tree function as a unit. Differential water availability, a long the year, may explain spores production variation.
Manejo de la vegetación, domesticación de plantas y origen de la agricultura en Mesoamérica
Authors: Casas Alejandro , Caballero Javier , Mapes Cristina , Zárate Sergio
Published: January 2019

A model of domestication of  plants in Mesoamerica based  on  selective management  of  plant populations and  communities by silvicultural practices is analyzed. Archaeological and  ethnobotanical information  suggests that  intentional manipulation of vegetation by Mesoamerican peoples has occurred in  past  and present times  in  order to  control availability  of  useful  plants. Forms of  management of  plant communities or  populations have  included tolerance, protection and  enhancement of individual  plants of  particular species  during clearance of  vegetation and  other ways of  perturbation. Processes of  artificial selection  (selection  in situ) may be carried out  through these  forms  of plant  management. These processes may cause significant morphological differences between wild and  managed populations as illustrated by the  cases  discussed here of  Anoda  cristata,  Crotalaria pumila,  Leucaena esculenta and  Stenocereus stellatus. Processes of artificial selection in  situ are mechanisms of  incipient domestication of  plants which  appear to  have  been   carried out  in Mesoamerica, perhaps since pre-agricultural times,  and  that  could contribute  to explain the processes that  led to  the  origins of agriculture in this region.
Pérdida secundaria de la fotosíntesis: el caso de las algas incoloras y de algunos parásitos
Authors: Gutiérrez-Cirios-Madrid Emma Berta
Published: January 2019

This review  pretends  to  illustrate a very interesting phenomenon  in  nature: the  secondary loss of the  photosynthetic function and its effects in chloroplast and mitochondrial  DNA. Here it is described how plastid  DNA has been reduced loosing those genes which encode for photosynthetic proteins. An example of the  mitochondrial DNA of a colouress alga is also explained. An hypothesis is proposed where the  number o f mitochondrial genes is maintained in  this  colourless organisms due to the energetic demand  on the organelle.
Variación morfológica de poblaciones silvestres y arvenses de Solanum ehrenbergii (Solanaceae)
Authors: Luna Cavazos Mario
Published: January 2019

Solanum ehrenbergii ("papa de monte" or "papa güera") is a species with edible tubers, valuable for the people from central Mexico. The farmers seek the tubers in "nopaleras" and "mezquitales'', but more commonly, they can be found in corn and bean cultivated fields, thus the plants are tolerated and encouraged. The environment in which S. ehrenbergii grows is variable, from harsh, in natural conditions , to bening, in the cultivated fields. The hypothesis is that it must exist a pattern of morphological variation in response to the origin of the populations. The objectives of the study were: a] to analyze the pattern of morphological variation between wild and weed populations of Solanum ehrenbergii and b] to document possible taxonomic differences and evolutive trends under management conditions. The methods included the morphological characterization of botanic material and the numerical analyses of data by cluster and principal components. The results indicated, that populations are grouped according to its origin wild or weed. Probably, the morphological variation of S. ehrenbergii is influenced for an incipient process of domestication in response to practices of tolerance, protection and encouragement carried out by the farmers.
Estudio palinológico de Ficus subgénero Pharmacosycea (Moraceae) de Veracruz, México
Authors: Lbarra-Manríquez Guillermo , Martínez-Hernández Enrique
Published: January 2019

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Plantas leñosas raras del bosque mesófilo de montaña III. Photinia parviflora Williams (Rosaceae)
Authors: Cuevas-Guzmán Ramón , Sánchez-Rodríguez Enrique V. , Núñez-López Nora M.
Published: January 2019

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Biología celular de Lacondonia schismatica. Análisis por microscopía electrónica y de fuerza atómica
Authors: Jiménez-García Luis Felipe , Reynoso-Robles Rafael , Fragoso-Soriano Rogelio , Agredano-Moreno Lourdes Teresa , Segura-Valdez María de Lourdes , González-Moreno Sergio , Ramos Clara Hilda , Martínez Esteban
Published: January 2019

We have previously described the cell nucleus of Lacandonia schismatica by transmission electron microscopy. In this paper, the ultrastructure of the cytoplasm of L. schismatica and photosynthesis activity were studied. In addition, atomic force microscopy was used to generate images of cell structure. Samples were prepared for standard electron microscopy using glutaraldehyde-paraformaldehyde fixation. Cells from tegument or receptacle show 1-3 Golgi apparatus. They have 3-7 cisternae, 0.81 ?m width. 0.04 ?m in diameter vesicles were also observed associated to cisternae. Mitochondria were 0.9 ?m long and 0.35 ?m width. Double membrane earphones-like plastids were observed with lipid inclusions but no developed tilacoids. No photosynthesis activity was detected in these cellular structures. Rough endoplasmic reticulum is similar to that of other eukaryotes and associated ribosomes are around 15 nm in diameter. A large nucleus and one o several vacuoles are present in cells of L. schismatica, therefore, leaving a very restricted portion for cytoplasm and organelles.
Anatomía de la corteza de algunas Gimnospermas
Authors: Yáñez-Espinosa Laura , Terrazas Teresa
Published: January 2019

The study of bark structural diversity of 17 gymnosperms was performed to describe it macro and microscopically, to elaborate a key and to compare them with den Outer's classification (1967). External bark allows to identify several species in the field. New anatomical features not reported previously were found, e.g. crystals in cellular walls in Araucariaceae and Taxodiaceae, lack of fibers in Cupressus guadalupensis and lignified sieve cells in the collapsed phloem of Pinus species. Ten species, described for the first time, were assigned to one of the types proposed by den Outer. Although the phylogenetic ideas established for the secondary phloem specialization suggested by den Outer have been questioned by the recent studies on fossil gymnosperms and cladistic analysis.
Cambios en la vegetación y uso del suelo en la Meseta P'urhepecha, el caso de Nahuatzen, Michoacán, México
Authors: Alarcón-Cháires Pablo
Published: January 2019

We used photogrametric analysis of 1970 and 1990, td study vegetation and land use changes in Nahuatzen, Michoacan. Forest cover was constant for this period, however, forest quality in terms of tree covery and height decreased and fragmentation increased. We relate this phenomenon to the agricultural crisis in the region, and to changes in economic activity from peasantry to forestry. The environmental consequences of such changes are discussed.
Efecto de la transformación de la selva a pradera sobre la dinámica de los nutrientes en un ecosistema tropical estancional en México
Authors: García-Oliva Felipe , Maass José Manuel
Published: January 2019

The effects of conversion of tropical deciduous forest into pasture were examined on the Central Pacific Coast of Mexico. Under forested  conditions two situations of nutrient cycles were determined: 1] hilltop locations where biological processes of soil were dominant; and 2] midslope locations where topographic characteristics were the main factor. When the forest cover was cut and burned, grasses were introduced for continuous cattle grazing, which led to changes in physical and chemical soil properties. Each topographic position responded differently to the conversion. The hilltop locations had higher nutrient retention capacity, which related strongly to higher soil organic matter content. In contrast, the midslope locations had a low nutrient protection capacity. After 11 years of use as pasture, the hilltop locations lost 700 kg N ha-1, 2,500 kg Ca ha-1 and 500 kg P ha-1, similar to the midslope locations losses.
Domesticación de plantas y recursos genéticos de México
Authors: Casas Alejandro
Published: January 2019

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Tendencias evolutivas en amartanto (Amaranthus spp.) bajo selección humana en México
Authors: Mapes Cristina , Basurto Francisco , Caballero Javier , Bye Robert
Published: January 2019

An inventory of species and races of amaranth greens (quintoniles) was made in the Sierra Norte de Puebla, Mexico. Their use, management and importance to the local residents were studied as well as the biological patterns of allocation of biomass and morphophysiological variation. The purpose of this work was to 1] study the biological richness of the species and races of greens-producing amaranth in this region and 2] study their evolutionary trends under human selection as compared with the species and races of grain-produdng amaranth. The promoted species and races are: A. hypochondriacus Mixteco and Azteca races ("chichiquelit") and A. cruentus Mexicano ("iztaquelit") and Africano ("quintonil rojo") races. The agrestal species are A. hybridus and A. spinosus. Three allocation patterns were found: a] grain producing races, b] greens-producing races and c] greens producing races which showed weedy growth characteristics. The results obtained suggest that there are two pathways for Amaranthus domestication, one associated to produce leaves as greens and another associated to the use of seeds as grain.
Origen, variación y tendencias evolutivas del Henequén (Agave fourcroydes Lem.)
Authors: Colunga-García Marín Patricia
Published: January 2019

Henequen was domesticated by the Maya people, from A. angustifolia, since pre-Hispanic times. It is one of the most important natural hard fibers worldwide because of its good quality and adaptation to ecologically restricted agrohabitats. This cultivar has maintained great economic and cultural value in the state of Yucatan. Ethnobotanical, morphological, and isozyme evidence were compiled to discuss the origin and evolution of henequen by human selection, the germplasm diversity available in the cultivated populations and that of the wild populations from which it could have arisen. Results suggested the occurrence of a drastic erosion of the genetic diversity maintained by the Maya, as a consequence of its cultivation under large plantations established at the beginning of this century for the cordage industry. At present, only three varities are cultivated: Sak ki (SK), Yaax ki (YK) and Kitam ki (KK), these last two in very small populations. SK and YK differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. KK is very similar to the wild types. Isozyme analysis indicated that wild populations have relatively high levels of variation, whereas all individuals of each henequen variety were identical. A parsimony analysis indicated two lineages: that of SK and YK, cultivated cordage plants selected for stronger and longer fibers, whose sister group is the tropical deciduous forest ecotype (SF); and that of ali other wild populations, which also included KK, the cultivated textile plants selected for finer fibers, and nearly extint in Yucatan. These  results support the hypothesis of the yucatecan origin of SK and YK from the SF ecotype, as well as the recent introduction of KK. Methodology used is discussed as well as research perspectives in this theme.
La domesticación de Stenocereus stellatus (Pfeiffer) Riccobono (Cactaceae)
Authors: Casas Alejandro , Valiente-Banuet Alfonso , Caballero Javier
Published: January 2019

This study aimed at analyzing processes of domestication by silvicultural forms of management. The effects of artificial selection on morphology and reproductive biology of Stenocereus stellatus are analyzed in wild; wild-managed in situ (silvicultural management) and cultivated populations from the Tehuacan Valley and La Mixteca Baja. People select the phenotypes of this columnar cactus species with relatively larger and sweeter fruits with thinner peel and fewer spines, favoring their numbers in wild populations managed in situ as well as in home gardens. Favorable phenotypes prevail in wild populations managed in situ, indicating that artificial selection has had significant effects under this form of management. These phenotypes are especially abundant in home gardens, which suggests that artificial selection is even stronger under cultivation. Favorable phenotypes are scarce or absent in non-manipulated wild populations. Such morphological divergence is maintained despite the reproductive system of S. stellatus, is self-incompatible in all populations, and even when there were not found spatial and temporal barriers for pollen flow between wild and cultivated populations. Abundance of favorable phenotypes in areas managed by people may be explained by action of artificial selection, while absence of some domesticated phenotypes in wild populations seems to be due to pollen incompatibility between some cultivated phenotypes and wild populations, but it could also be due to pressures of natural selection against cultivated phenotypes.
La domesticación de Leucaena (Fabaceae, Mimosoideae) en Mexico
Authors: Zárate-Pedroche Sergio
Published: January 2019

This paper reviews multidisciplinary information about the domestication process of some species of Leucaena (Fabaceae, Mimosoideae) in Mexico. Taxonomical, phytogeographical, archaeobotanical, ethnohistorical, ethnobotanical and genetical (isoenzymes) information was integrated in a model of the domestication process of these trees and shrubs. The model is directed to answer how domestication was achieved by means of seed propagation, given the length of the life cycle and predominant open pollination. Most early domesticated trees in Mesoamerica present these characteristics, in contrast with vegetative propagation which was typical of early domesticated trees in the Middle East. Results of this research suggest that, while in situ tolerance and cultivation lead to the maintenance of desired product quality (although at a slow rate), only by diffusion is it possible to enhance such quality. Diffusion would result in the establishing of cultivation, and it must prevail in order to avoid loss of quality, productivity, or both. Cultigens are obtained through an extensive selective sampling; locally, diffusion and management generate variants.
Los parientes silvestres del chile (Capsicum spp.) como recursos genéticos
Authors: Hernández-Verdugo Sergio , Guevara-González Ramón G. , Rivera-Bustamante Rafael F. , Vázquez-Yanes Carlos , Oyama Ken
Published: January 2019

Results of studies on variation of genetic, morphological, germination and resistance to PHV (pepper huasteco virus) geminivirus of wild populations of C. annuum collected in Sinaloa state are presented in order to show the importance of studing the wild relatives of cultivated plants. The study on resistance to PHV geminivirus with the biolistic method showed high variability between populations in this trait. Sorne populations showed low levels of disease symptoms, and they are very promising for further studies on virus resistance. The isozymes study showed that ali the populations maintain high genetic variability (heterozygosity ranged between 0.255 to 0.325). Ali the wild C. annuum populations showed high variability in ten of eleven morphological traits analyzed. Most of the germination tests showed a great variability in response among the populations studied. Ali the wild C. annuum populations did not germinate under dark conditions, suggesting the existence of seed dormancy. In conclusion, wild relatives of pepper maintain high levels of variability of genetic, morphological and germination capacity, and they have potentially useful genes; they are valuable genetic resources that we need to study and to preserve.
Botánica, América Latina y el próximo milenio
Authors: Raven Peter H.
Published: January 2019

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Biodiversidad, conservación y desarrollo sustentable: Algunas reflexiones respecto al futuro
Authors: Sarukhán José
Published: January 2019

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Biodiversidad y conservación en América Latina: situación actual y perspectivas
Authors: Forero Enrique
Published: January 2019

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Theobroma bicolor Humb. & Bonpl. (Sterculiaceae, "Cuapataxtle") en el Municipio de Ayutla de los Libres, Guerrero. Composición Florística de los huertos y aspectos etnobotánicos
Authors: Rendón-Aguilar Beatriz , González Soto Graciela , Oble-Delgadillo María Isabel , Ojeda-Cornejo Virginia , Parra-Padilla Rosa Elvira , Pérez-González Estela , Ramírez-Hernández Lydia
Published: January 2019

El presente trabajo tuvo como objetivos: 1] describir la composición florística de los huertos donde crece Theobroma bicolor; en el municipio de Ayutla de los Libres, Guerrero; 2] describir los aspectos etnobotánicos relacionados con los usos de T. bicolor y 3] reportar la presencia de T. bicolor en el estado de Guerrero, específicamente en el Municipio de Ayutla de Los Libres-: Se muestrearon 9 huertos ubicados en diferentes localidades con diferente composición étnica. Se obtuvo el número total de especies por área muestreada, número de individuos por especie y densidad relativa de cada especie. La descripción de los usos de T. bicolor se obtuvo mediante encuestas a indígenas y mestizos. Se observa una heterogeneidad en la riqueza de especies presentes en los huertos, en el tipo de especies y en las densidades relativas. En general, los huertos cercanos a la cabecera municipal, conservan una composición florística variable y una alta densidad relativa de diversas especies frutales y del cuapataxtle. Los huertos alejados de la cabecera municipal y manejados por indígenas mixtecos también presentan una heterogeneidad alta pero las densidades relativas en general son bajas, incluyendo la de cuapataxtle. Se concluye que la composición florística variable en los huertos, así como las diferencias en las densidades relativas de las especies, incluyendo el cuapataxtle, reflejan la concepción tradicional de manejo de los huertos, la ubicación de los huertos con respecto a la cabecera municipal de Ayutla, y la importancia de la cercanía con sitios de comercialización de productos.
Fitoplancton del Lago Zempoala
Authors: García-Rodríguez Judith , Tavera Rosaluz
Published: January 2019

The phytoplankton of lake Zempoala was studied from April 1996 to July 1997. The taxonomy, ecology and geographical distribution of species show that their presence is more common in temperate than tropical areas. Seasonal variations in patching, density and dominant species of the phytoplankton are corresponding with the annual physical and chemical periodical changes (allogenics), and with the zooplancton community interactions (autogenics).
Reseña de libro: Botánica económica en bosques tropicales. Principio y método para su estudio y aprovechamiento.
Authors: Casas Alejandro
Published: January 2019

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Desarrollo del gametofito femenino de Tagetes patula (Asteraceae)
Authors: García-Aguilar Marcelina , Engleman E. Mark , Pimienta-Barrios Eulogio
Published: January 2019

The genus Tagetes reproduces sexually by seed, but recent morphological and hybridization studies in Tagetes patula suggest an apomictic type of reproduction (seed development without fertilization). In order to determine the sexual or apomictic origen of the embryo, we have studied megasporogenesis, megagametogenesis and the early development of the embryo. Tagetes patula L. has a typical ovule for the family Asteraceae: anatropous, unitegmic, tenuinucellate and with basal placentation. A single hypodermal archesporial cell develops directly as the megaspore mother cell. Megaspogenesis is normal and embryo sac develops from the chalazal megaspore. The embryo sac is of the Polygonum type. Female ray flowers show irregularities in megagametophyte development such as formation of more than eight nuclei, inverted polarity and incomplete differentiation of the megagametophyte cells in mature flowers. These irregularities do not necessarily prove apomictic reproduction in Tagetes patula.
El uso de los encinos en la región de La Malinche, Estado de Tlaxcala, México
Authors: Espejel-Rodríguez María Mercedes A. , Santacruz-García Noé , Sánchez-Flores Moisés
Published: January 2019

Based on the review of herbarium specimens ten species of oaks (Quercus) were identified in the region of La Malinche, Tlaxcala, Mexico. A list of species and a distribution map of each one of them in the region is presented. A survey, through a direct interview, on to the form of utilization of the resource was conducted among the inhabitants of nine localities stablished in the zone. An analysis of the socioeconomic importance of these elements is made. Among the principal uses detected are the utilization as fuelwood and coal, wood, employment of the verbiage as organic fertilizer, and use of the bark as medicine.
La vegetación escletófila perennifolia del Valle de Tehuacán, Puebla y sus similitudes con la vegetación esclerófila de climas mediterráneos
Authors: Flores-Hernández Noe , Valiente-Banuet Alfonso , Dávila Patricia , Villaseñor José Luis
Published: January 2019

The evergreen sclerophyllous vegetation of the Tehuacán Valley is described and compared with 4 of the 5 zones with Mediterranean-type climates. In the vegetation description structural aspects such as cover, height, frequency and life forms spectrum were considered. This vegetation type called Mexical has a close similarity in life forms spectrum with annuals predominance with the Mediterranean-type vegetation. Therefore, the evergreen sclerophyllous vegetation distribution within the tropics not only is explained in relation with  mediterranean-type climates, and also because by historical factors .
Ecología y evolución de la polinización por engaño
Authors: Castillo Reyna A. , Cordero Carlos , Domínguez César A.
Published: January 2019

In this work we reviewed the biology of deceit pollination from an ecological and evolutionary perspective. Species pollinated by deceit are characterized because a percentage of their flowers do not produce rewards, and therefore these species get the advantages derived from pollinators without paying the costs. In this review, we first described the different types of deceit occurring in nature, as well as the selective pressures involved on its evolution. We then reviewed and discussed the theoretical framework of deceit pollination and the relevant aspects of its main components: frequency-dependent se lection, flower resemblance, and the sensorial capacities of pollinators.
Una mirada de la situación actual de la anatomía de la madera
Authors: Dickson William C.
Published: January 2019

The primary objective of this contribution is to present a view of how and to what extent comparative systematic wood anatomy has changed over the past fifty years and what research priorities should be for the future. Wood anatomy has resolved itself into a series of subdisciplines, each of which deals with particular questions. Thus, wood anatomical study has passed successively from a consideration of wood data based upon well-defined and largely unchallenged principles to a more flexible view of wood evolution based on structure-function relationships at the cellular level and the establishment of correlations between anatomy and ecology. The questions and phenomena to be investigated are so complex and variable that, in many cases, they can be analyzed only through the active cooperation of a group of experts.
Anatomía de la madera de Anacardiaceae con énfasis en los géneros americanos
Authors: Terrazas Teresa
Published: January 2019

An overview of systematic wood anatomy is presented and a synthesis of wood characters for 29 of the 32 genera of Anacardiaceae distributed in America is given. The analys is showed that wood of American genera has the divers ity observed for the Anacardiaceae as a whole. There is a high in cidence of genera with ring-porous wood in America compared to o ther continents. Also shorter vessel element and fiber lengths occur in genera distributed in America. The comparative studies that used wood features for Anacardiaceous genera such Anacardium, Astronium, Myracrodnwn, Pistacia, and Tapirira showed that qualitative and quantitative characters help to distinguish species. The neecl for increasing wood collections of Rhus, Schinus, and Toxicodendron species is emphasized.
Los Géneros Docidium, Penium, Haplotaenium, Pleurotaenium, Tetmemorus y Triploceras (Desmidiales, Chlorophyta) en Cuba
Authors: Martínez-Almeida Víctor M.
Published: January 2019

This is a further contribution to the knowledge of the desmid flora of Cuba. One hundred and sixty samples collected from the most important regions in regard to occurrence of desmids and diversity of mi croalgae species in Cuba (Pinar del Río, Isla de la juventud, Ciénaga de Zapata, Matanzas and San Felipe, Camagüey), were examined. Emphasis was made on the taxonomic survey of those  cylindrical" representative genera. 22 infrageneric taxa belonging to 17 species were identified, 18 of which are new records from the country. Some populations examined showed a wide morphological variability. Each taxon is briefly described based on Cuban material. Original drawings and comments about distribution and synonymy according to the available taxonomic literature are included.
Distribución geográfica y diversidad de los musgos neotropicales
Authors: Delgadillo-M. Claudio
Published: January 2019

Current data indicate that the neotropical moss flora consists of about 3869 species and varieties. Despite our knowledge of its distributional patterns, the areas of high diversity and endemism cannot be precisely identified, yet. More than 44% of the species and varieties are endemic to the neotropics and about 32 genera contain 30 or more species in the area. Basic catalogues of species per country or region along with methods of systematic and biogeographic analyses are necessary to examine our hypotheses on the origins of diversity and the relationships of the flora.
Ecofisiología vegetal: una herramienta para la conservación y restauración ecológica
Authors: Barradas Victor L.
Published: January 2019

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Modificación del microclima con énfasis en la conservación y la restauración ecológica
Authors: Barradas Victor L. , Gitierrez-Salazar José Alejandro
Published: January 2019

The deforestation of a site for agriculture and/ or cattle raising purposes changes either microclimate and soil properties. These environmental changes can act as physical barriers which drastically limits tree species establishment in reforestation . From microclimatic point of view, the study of the energy balance plays a key role when the original environment is severely changed. The net energy in a site is mainly dissipated by latent and sensible heat fluxes which are associated to evapotranspiration and thermal regimes,respectively. The analyses of these fluxes allow to design control systems to reduce the high evaporation rates and high temperatures registered in a deforested site. Energy balance, latent and sensible heat fluxes and other components are analysed, and some techniques to manipulate energy balance are also presented.
Fuentes de agua utilizadas por las plantas desérticas y su importancia en planes demanejo y restauración ecológica
Authors: Squeo Francisco A. , Olivares Nancy , Valenzuela Alejandra , Pollastri Alberto , Aguirre Evelyn , Aravena Ramón , Jorquera Carmen , Ehleringer James R.
Published: January 2019

Water is the most important factor that affects primary production and plant structure in arid ecosystems. Because desert plant species can present different mechanisms to use water from different supplies in the substratum (superficial and profound water), the knowledge of these mechanisms is important to take it into account for ecological conservation, management and restoration planning. These mechanisms were compared in the coast north-center of Chi le (29' 43' S, 71' 14' O, 300 msnm) among different shrub species in two contrasting precipitation years. There were identified six functional groups in the studied system which were based on the mechanisms of the water uptake and use, habit ( deciduous, evergreen) and root architecture. Water supplies were identified by stab le isotopes. Because goat overgrazing could have a different impact among the functional groups, it is postulated that this action will decrease the utilization of superficial water. An ecological restoration and/or management planning should maximize the potentiality utilization of all water supplies in order to restore primary production and system stability. Furthermore, this kind of planning should take into account future sceneries as climatic tendencies (e.g. decreasing precipitation) or social and cultural changes (e.g. promoting intensive goat livestock instead of extensive).
Propuesta de una técnica para herborizar plantas dela familia Crassulaceae
Authors: Gutiérrez-Salazar José Alejandro , García-Mendoza Abisaí
Published: January 2019

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Enriqueta García de Miranda (1928-1999)
Authors: Trujillo Teresa Reyna
Published: January 2019

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Rodolfo Palacios Chávez (1929-1999)
Authors: Rodríguez-J. Concepción , Quiroz-G D. Leonor
Published: January 2019

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Análisis de crecimiento de tres especies de Caesalpinia (Leguminosae) de la selva baja caducifolia de Chamela, Jalisco
Authors: Rincón Emmanuel , Huante Pilar , Álvarez-Añorve Mariana
Published: January 2019

El objetivo de este estudio es conocer las características de crecimiento y asignación de biomasa de tres especies de Caesalpinia (Leguminosae ), en la altamente diversa y estacional selva baja caducifolia de Chamela, donde la temporada de crecimiento de las especies vegetales está limitada por la época de lluvias. Las especies, aunque relacionadas filogenéticamente, presentaron diferencias en su velocidad de crecimiento y asignación de biomasa, lo cual sugiere una explotación diferencial de los recursos, misma que favorecería la coexistencia. Se registraron diferencias en la tasa relativa de crecimiento (RGR), el cociente raíz / parte áerea (R/S), la tasa de asimilación neta (E), los patrones de asignación de biomasa y el área total producida de las especies estudiadas. Caesalpinia eriostachys y C. platyloba presentaron características similares entre sí pero contrastantes con las de C. sclerocarpa . Los parámetros relacionados con E explicaron la RGR de las tres especies estudiadas mejor que aquellos relacionados con el área foliar específica (SLA).
Cronología reproductora de Ceratozamia mexicana (Cycadales)
Authors: Sánchez-Tinoco María Ydelia , Engleman E. Mark , Vovides Andrew P.
Published: January 2019

En Cemtozamia mexicana Brongn. el desarrollo de la semilla se cumple en 24 meses desde la iniciación de los óvulos en agosto hasta el desarrollo completo del cuerpo del embrión. Durante los tres primeros meses ocurre la megasporogénesis y la megagametofitogénesis. Al finalizar febrero el gametofito es cenocítico. La celularización del gametofito termina en mayo y comienzan otros cambios: endurecimiento del gametofito, lignificación de la capa pétrea, desaparición de tricomas y acumulación de almidón en el gametofito. La polinización probablemente ocurre entre febrero y marzo. Al inicio de septiembre, aparecen proteínas y gotas de aceite en el gametofito. La semilla se dispersa en septiembre; puede presentar arquegonios y ocasionalmente suspensores en desarrollo. La fertilización ocurre aproximadamente en el período de la dispersión fuera de la planta madre. Los suspenso res crecen durante cinco meses y el cuerpo del embrión se desarrolla en cuatro meses. Previo a la presencia de un embrión, esta semilla se dedica a proveerse de nutrimentos y protegerse.
Respuesta germinativa y crecimiento de plántulas de Mammillaria magnimamma (Cactaceae) bajo diferentes condiciones ambientales
Authors: Ruedas Marcela , Valverde Teresa , Castillo-Argüero Silvia
Published: January 2019

Se abordó experimentalmente el estudio de la respuesta germinativa y el crecimiento de plántulas de Mammillaria magnimamma . Se determinó el porcentaje final de germinación y la velocidad de germinación de las semillas bajo diferentes condiciones de luz/oscuridad, temperatura y pretratamientos de acidez. Las semillas son fotoblásticas positivas y su viabilidad es alta (86%); el requerimiento de luz disminuyó al aumentar la edad de las semillas. La variación en la temperatura afectó la velocidad de germinación y los pretratamientos de acidez no tuvieron un efecto significativo sobre la germinación. Se estudió el crecimiento de plántulas de esta especie en condiciones de invernadero bajo un diseño factorial que incluyó dos niveles de luz, dos de disponibilidad de nutrimentos y dos de frecuencia de riego. Las plántulas son de crecimiento lento (entre 0.014 y 0.027 g g-1 d-1) y responden positivamente a la adición de nutrientes y a los niveles elevados de exposición lumínica.
Carbohydrates and Flowering in Hesperaloë funifera (Koch) Trel. (Samandoque)
Authors: Mclaughlin Steven P. , Williams Ryan R.
Published: January 2019

Several researchers have noted that flowering in Agavaceae requires substantial resources, but few studies have attempted to directly measure such resources. T his study addresses the hypothesis that fruit set in Hesperaloë funifera is limited by available carbohydrates. The accumulation of total non-structural carbohydrates (TNC) prior to flowering was measured, and total requirements for carbohydrate were estimated. Hesperaloë funifera was found to accumulate fructans, and roots were an important organ for storage of accumulated carbohydrates. Carbohydrates stored in the plant prior to flowering are sufficient to meet only about onethird of the carbohydrate needed to produce an average inflorescence with 1 % to 2% fruit set. All of the carbohydrate produced by photosynthesis from May through August is needed to support flowering and fruit production. Low percentage fruit set in Hesperaloë funifera is probably due to a deficiency of carbohydrate resources.
Maguey ( Agave spp.) utilization in Mesoamerican civilization: a case for precolumbian "Pastoralism"
Authors: Parsons Jeffrey R. , Darling J. Andrew
Published: January 2019

Archaeologists have generally neglected the implications of maguey cultivation in their assessments of prehispanic Mesoamerican cultural development in the highlands of central and north-central Mexico. Recent ethnographic, ethnohistoric, and archaeological studies provide the basis for the formulation of new hypotheses about the importance of the complementarity of maguey and seed-based cultivation in ancient Mesoamerica. We see cultivated maguey as functionally analogous in Mesoamerica to the role of pastoralism in the development of archaic civilizations in the Andes, Asia, Africa, and Europe. Future archaeological and ethnobotanical research should provide key new information for refining and testing these hypotheses.
Evolución de la familia Agavaceae: Filogenia, biología reproductiva y genética de poblaciones
Authors: Eguiarte Luis E. , Souza Valeria , Silva-Montellano Arturo
Published: January 2019

La familia Agavaceae abarca ocho géneros con biologías reproductivas contrastantes, ya que pueden ser iteróparos (se pueden reproducir varias veces) o semélparos (producen una sola inflorescencia en su vida, para después morir) y tienen una notable diversidad de morfologías florales y de polinizadores (desde abejas a murciélagos, pasando por colibríes y polillas). Revisamos la biología reproductiva de cada género ( Yucca, Hesperalë, Furcraea, Beschorneria, Agave, Manfreda, Polianthes y Prochnyanthes) e intentamos una síntesis de lo que se conoce de su genética de poblaciones y evolución. Para ello reconstruimos su filogenia a partir de datos de los ITS l e ITS 2 y calibramos un reloj molecular. Para fin es comparativos utilizamos a Hosta, aunque revisarnos otros géneros que se han considerado cercanos a la familia. Por último, discutimos los patrones evolutivos en la familia, analizando los diferentes caracteres en la filogenia.
In Memoriam Ramón Riba y Nava Esparza
Authors: Pérez-García Blanca , Pacheco Leticia , Espejo-Serna Adolfo , López-Ferrari Ana Rosa
Published: January 2019

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Efecto de dos especies de árboles remanentes y de un pasto en la capacidad amortiguadora del pH del suelo
Authors: Nava-Mendoza Maribel , Galicia Leopoldo , García-Oliva Felipe
Published: January 2019

La capacidad amortiguadora del pH del suelo fue afectada por dos especies de árboles remanentes de la selva y por una especie de pasto. La diferencia más importante entre las dos especies de árboles remanentes fue el grado de neutralización del complejo de intercambio catiónico: el suelo de C. elaeagnoides estuvo dominado por los cationes alcalinos (i.e. Ca2+, Mg2+ , K+) a diferencia del suelo de C. eriostachys, que estuvo dominado por H', debido a su mayor tasa de nitrificación. En contraste, la especie de pasto tuvo una menorcapacidad de amortiguamiento del pH y el factor principal que controló el pH en la solución del suelo fue la fuerza del ácido. Esto sugiere, que las condiciones de manejo en este ecosistema han reducidos los mecanismos de protección de nutrientes del suelo, asociados principalmente a las especies vegetales