Search

Copyright of Revista CienciaUAT is the property of Universidad Autonoma de Tamaulipas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Si bien se ha mejorado la precisión de los escenarios del cambio climático global, la falta de datos climáticos de varias regiones del mundo significa que algunas predicciones presentan gran incertidumbre. Los estudios climáticos locales son críticos para la calibración de escenarios climáticos globales. El objetivo fue evaluar tendencias climáticas dentro de la cuenca de Cuatro Ciénegas (CCB). Específicamente: 1) identificar tendencias potenciales en el comportamiento de la temperatura y la precipitación; 2) evaluar la naturaleza y dirección de los cambios en la frecuencia de eventos climáticos extremos (ECE), y 3) detectar cambios en la variabilidad interanual de la lluvia. Para lograr estos objetivos se analizó una base de datos de 70 años de variables climáticas de la estación meteorológica CCB. Los datos se sometieron a análisis de tendencias utilizando dos paquetes de software diferentes; la frecuencia ECE se evaluó mediante análisis de Chi-cuadrado y los datos de lluvia se analizaron usando el índice pluviométrico estandarizado de sequía. La temperatura mínima (Tmin) aumentó al menos 2 °C en casi todos los meses y la temperatura media (Tmean) subió 2 °C, pero sólo en meses de verano. En los ECE los inviernos se han vuelto más fríos, mientras que los veranos se han vuelto más cálidos; se incrementó la frecuencia de las olas de calor en los últimos 36 años. Sin embargo, los patrones mensuales de lluvia presentaron una gran variabilidad que oscureció cualquier tendencia en la frecuencia de ECE de lluvia. En los últimos 36 años, las frecuencias de eventos de lluvias intensas asociadas con ciclones tropicales y sequías intensas han aumentado.

A neotype for the name Echinocactus fossulatus is here designated and the first record of Thelocactus hexaedrophorus, an endemic species to Mexico, for Aguascalientes is reported. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pallid bats, Antrozous pallidus , despite being primarily insectivorous gleaning predators, consume nectar of the cardón cactus, Pachycereus pringlei , in the Sonoran Desert. It is unknown whether nectar feeding occurs in the Chihuahuan Desert of Texas, where pallid bats covered in pollen have been captured. We collected pollen samples from 67 pallid bats in Brewster County, Texas, United States, between April and August 2018. Pollen-covered pallid bats were captured in every month sampled. Pollen densities were three times higher on wings than on the head or ventral body. In all samples collected, the pollen was homogeneous and identified as Agave pollen. Although two species of Agave , A. havardiana and A. lechuguilla , occur in this region of Texas, linear discriminant analysis classified 701 of 723 (97%) of pollen grains analyzed as A. lechuguilla. Additional evidence from infrared video footage collected in August 2018 indicated that pallid bats became covered in A. lechuguilla pollen while consuming nectar. Pallid bats might be engaging in facultative nectarivory across their range and could be important nocturnal pollinators. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological monitoring is essential to understand population dynamics, ecological processes and emerging problems. In this study we determine the richness and abundance of diurnal raptors in the Fernandez Canyon State Park in Durango, Mexico. We detected a total of 11 species; five of them are under some risk category according to the Norma Oficial Mexicana 059-2010, Sharp-shinned Hawk (Accipiter striatus), Cooper´s hawk (A. cooperii), Common Black-Hawk (Buteogallus anthracinus), Harris' Hawk (Parabuteo unicinctus) and Red-shouldered Hawk (Buteo lineatus). The most abundant species were Coragyps atratus, Cathartes aura and Buteo jamaicensis. The habitat where most records were obtained was the gallery forest. Conservation threats for raptors in the area include habitat loss, hunting, and electrocution.

The flat-headed myotis (Myotis planiceps) was declared extinct in 1996 but rediscovered in 2004, thus the reference to a revenant, one who came back from the dead, as it was declared extinct in 1996 but rediscovered in 2004. However, the species still faces serious extinction risk. To aid in the strategic planning and priorities for conservation, we studied roosting ecology. These bats inhabit the Chihuahuan Desert in one of the smallest distributional ranges of any mammal. Using radiotelemetry, we located 25 summer roosts, all in the skirts of dry leaves of yucca trees (Yucca carnerosana). We conclude that to roost, these bats search for clumps of tall yucca trees with a mean height of 3.93 m and mean width of skirts of 1.35 m. [ABSTRACT FROM AUTHOR]

El objetivo de este estudio consistió en evaluar los cambios en la estructura y composición florística del matorral desértico micrófilo a partir de la aplicación de una técnica de restauración ecológica y la ocurrencia de incendios naturales en diferentes periodos en el Desierto Chihuahuense. Mediante cinco tratamientos (testigo (MDMt), rodillo aireador aplicado en 2004 (RA04), en 2008 (RA08), en 2011 (RA11) y área incendiada del 2011 (IN11)) se determinaron la diversidad y la similitud entre especies con los índices de Shannon y Sørensen, así como su índice de valor de importancia (IVI). Se registraron 28 especies arbóreas y arbustivas pertenecientes a 14 familias. Asteraceae, Cactaceae y Fabaceae destacaron por su abundancia. El índice de Shannon reveló una mayor riqueza (H’ = 2.103) en el tratamiento RA1 mientras que el IN1, el menor (H’ = 1.21). La máxima similitud se verificó entre los tratamientos RA04 y RA08 con 76 % y lo contrario entre RA11 y RA08 con 44 % de acuerdo al índice de Sørensen. La Prueba de Kruskall-Wallis mostró que no hay diferencia significativa entre tratamientos respecto al IVI (F= 2.463, G.L. = 4, P = 0.261). El tratamiento de rodillo aireador incrementó, a corto plazo, la riqueza de especies y disminuyó substancialmente la dominancia de especies de Cactaceae y Agavaceae, y favoreció la cobertura de Larrea tridentata. El tratamiento de fuego redujo la cobertura de esta última, además de la de Jatropha dioica, Opuntia engelmannii y estimuló la presencia y cobertura de Viguiera stenoloba, Condalia spathulata y Ziziphus obstusifolia.

Biological monitoring is essential to understand population dynamics, ecological processes and emerging problems. In this study we determine the richness and abundance of diurnal raptors in the Fernandez Canyon State Park in Durango, Mexico. We detected a total of 11 species; five of them are under some risk category according to the Norma Oficial Mexicana 059-2010, Sharp-shinned Hawk (Accipiter striatus), Cooper's hawk (A. cooperii), Common Black-Hawk (Buteogallus anthracinus), Harris' Hawk (Parabuteo unicinctus) and Red-shouldered Hawk (Buteo lineatus). The most abundant species were Coragyps atratus, Cathartes aura and Buteo jamaicensis. The habitat where most records were obtained was the gallery forest. Conservation threats for raptors in the area include habitat loss, hunting, and electrocution. [ABSTRACT FROM AUTHOR]

Understanding home range size and habitat preferences is an important component of monitoring species in steep decline. Sprague's Pipit (Anthus spragueii) is a declining grassland specialist with a substantial portion of its population wintering in the highly threatened grasslands of the Chihuahuan Desert. We radio-tagged and tracked 10 wintering pipits between 2014 and 2017 at 3 sites across northern Mexico to generate baseline home range estimates and habitat preferences on their wintering grounds. We found that mean home range and core-use area size with 95% and 50% kernel density estimators were 11.4 ha and 2.4 ha, respectively, almost twice as large as some other grassland specialist passerines. Two birds left the study area and one individual shifted its home range 1.3 km after 20 d of monitoring, indicating that some individuals are flexible in their space use strategies. Within their home ranges, pipits selected grasslands with more bare ground and less "other cover" (litter, duff, animal excrement, and rocks) than what was available on the landscape. We found no relationship at the microhabitat scale between pipits and grass height nor shrub cover and heights, which in previous studies have been shown to influence habitat selection at larger scales. These findings may reflect different habitat use, diet, and predator avoidance strategies than other grassland passerines that select for denser grass cover during winter in the Chihuahuan Desert and highlight the importance of structurally heterogeneous grasslands. For this reason, strategies to manage and conserve Chihuahuan Desert grasslands and its avifauna must consider the diverse habitat and area needs of grassland birds to be effective. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The distribution of Anna's hummingbird (Calypte anna) comprises the western coast of the U.S.A., the southern coast of British Columbia in Canada and the northwestern Pacific coast of the Mexican state of Baja California entering Arizona and north western Sonora. In general, its wintering grounds are undefined and winter irruptions have been reported in places like the Texas Gulf coast and some other locations in the eastern United States and in Northern Mexico. In the metropolitan area of La Laguna (Durango and Coahuila states) it is a common urban hummingbird throughout the year even though its reproduction has not been recorded. Records of its presence and nesting in La Laguna are listed pointing towards a wider distribution of Anna's hummingbird in Mexico. [ABSTRACT FROM AUTHOR]

Durante tres inviernos consecutivos (2008-2010), realizamos monitoreos de aves de pastizal en la región de Cuchillas de la Zarca, al sur del estado de Chihuahua y norte de Durango, México, con el objeto de determinar la abundancia y distribución del gorrión de Baird (Ammodramus bairdii), ave migratoria de pastizales. Los resultados demuestran que esta región es muy importante para esta especie, pues estimamos una densidad poblacional de 59.8±14.6 individuos/km2. La distribución del ave fue amplia, localizándose en la mayor parte de los cuadrantes de la zona de estudio (n=16), aunque la abundancia relativa fue superior en los cuadrantes centrales. El análisis de la vegetación de los sitios donde registramos A. bairdii permite suponer que existe similitud entre el hábitat de sus áreas no reproductivas y el de sus áreas de reproducción. Por la falta de información sobre esta especie en la época no reproductiva en México, los datos obtenidos en este estudio son útiles para comprender algunos aspectos de su ecología no reproductiva.

With the aim of assessing the extent of geographical rarity of Mexican Cactaceae, we calculated the distribution size (area of occupancy) of 142 species from the Chihuahuan Desert. In addition, using 2 variables (number of localities and range size), we preliminarily assessed their conservation status using the current IUCN Red List criteria. The results showed enormous variation in the areas of occupancy, although from the biogeographic and conservation perspective the most exceptional group comprises the extremely narrow endemics (42 species), whose range is restricted to areas smaller than 10 km2. Our results reinforce the reputation of this plant family as exceptionally rare geographically. We suggest that geographical rarity of Cactaceae in the Chihuahuan Desert is a natural phenomenon; however, we propose that the range of several species has been influenced by human activities. Regarding the conservation status of the species, 75 of them are categorized as Least concern. The remaining 67 species (47.2%) fall in 1 of the 3 categories of threat (27 Vulnerable, 11 Endangered, and 29 Critically endangered). These figures confirm the critical conservation status of Mexican Cactaceae.Se calculó el tamaño de la distribución (área de ocupación) de 142 especies de cactáceas del Desierto Chihuahuense, con el objeto de evaluar su grado de rareza geográfica. Además, mediante el uso de 2 variables (número de localidades y tamaño de distribución), se estimó de manera preliminar su estado de conservación usando los criterios actuales de la Lista Roja de la UICN. Los resultados mostraron gran variación en las áreas de ocupación. Sin embargo, desde una perspectiva biogeográfica y de la conservación, el grupo de especies más excepcional corresponde a las endémicas restringidas (42 spp.), cuyas áreas de distribución son menores de 10 km². Los resultados fortalecen la reputación de las cactáceas de ser una familia de plantas excepcionalmente rara geográficamente. Se sugiere que la rareza geográfica en cactáceas es un fenómeno natural; sin embargo, se propone que la distribución de algunas de las especies ha sido influenciada por actividades humanas. En lo que respecta al estado de conservación de las especies, 75 pueden ser consideradas bajo la categoría de Preocupación menor, mientras que las restantes 67 (47.2%) caen en alguna de las categorías de amenaza (Vulnerable = 27 spp., Amenazada = 11 spp., Críticamente amenazada = 29 spp.). Los resultados confirman el grave estado de conservación de las cactáceas mexicanas.

The Sierra Rica belongs to the Flora and Fauna Protection Area Santa Elena Canyon, and it is placed in the municipality of Manuel Benavides of Chihuahua, Mexico, and is considered a biogeographic sky island. Here we present for the first time, a biogeographic characterization of this area, providing a review that will help to understand plant diversity, its origins and distributional patterns. We made a bibliographic review complemented with fieldwork performed at the study area. The geological origin of Sierra Rica goes back to the volcanic activity of the Cenozoic era, giving rise to abiotic and biotic features relevant to plant distribution. Among those factors we identified microclimates, soil and physiographic features, as well as evolutionary forces like selection, soil microorganisms, dispersal mechanisms, and organismic interactions. The establishment of the pine and oak forests, grassland and shrub land communities have suffered changes through time, however, there are elements that did not change composition, only change distribution. [ABSTRACT FROM AUTHOR]

Estudios multidisciplinarios de geología del Cuaternario, ecología y geofísica en la región que actualmente ocupa el Lago-playa El Fresnal, norte del estado de Chihuahua, indican que se trata de una cuenca en extensión de tipo medio-graben, caracterizada por un lago-playa en la parte basal, rodeado por piemontes cubiertos por abanicos aluviales. El tectonismo extensional produjo zonas de fallas normales, bloques basculados con expresiones geomórficas diferenciales y volcanismo. El area del bloque levantado es la fuente principal de aportes detríticos; sin embargo, debido ala naturaleza asimetrica de la cuenca, los sedimentos provenientes del bloque hundido se encuentran espacialmente mas distribuidos. Resultado del bascularniento, los abanicos aluviales se segmentaron quedando las superficies mas antiguas en Ia parte distal del bloque levantado y en Ia parte proximal del bloque hundido. Hasta ahora, la evolución de los abanicos aluviales ha sido considerada como el resultado de las variables tectónicas y climáticas; sin embargo, la función e importancia relativa que estas tienen en el control de la sedimentación tanto de los abanicos aluviales como de los rellenos de la cuenca no ha sido aun resuelto. Por ejemplo, algunos autores enfatizan la influencia de los cambios climáticos, mientras que otros ponderan el efecto de la actividad tectónica. En el presente trabajo se analizan los aspectos geomorfológicos de los abanicos aluviales, su posición topográifica relativa, el grado de disección y desarrollo de suelos, el tipo de drenaje, y de manera general, las distintas facies sedimentarias. Nuestros resultados indican que en la región existen tres generaciones de abanicos aluviales, formados durante las principales variaciones climaticas del Cuaternario Tardío. Esta interpretación es consistente con los principales cambios climáticos registrados en la estratigraffa paleolacustre del norte de México y del suroeste de los Estados Unidos. Los abanicos aluviales estan formados principalmente por depósitos de tipo debrisflow, resultado de precipitaciones abundantes de corta duración, producidas probablemente por cambios en las condiciones climaticas de relativamente húmedas a aridas. Las facies sedimentarias de estos depósitos contrastan con las producidas por regímenes tipicamente fluviales. doi: https://doi.org/10.22201/igeof.00167169p.2004.43.3.971

Se realizó un estudio florístico y se consideraron las relaciones fitogeográficas del matorral xerófilo en el Valle de Tecozautla, Hidalgo, México. Se inventariaron 479 especies de plantas vasculares, 298 géneros, 80 familias y 51 taxa infraespecíficos. Las familias con mayor número de especies son Asteraceae (62), Poaceae (46) y Fabaceae (33). Las hierbas son la forma de vida dominante. La mayoría de las especies se distribuyen en la zona árida-semiárida. El 37.8% de las especies se distribuyen en México y el 14.3% desde el sur de Estados Unidos de América a México. Con base en el coeficiente de similitud de Preston, se comparte el 71% de los géneros con el Valle de Actopan, 66% con El Olivo, Ixmiquilpan, ambos localizados en Hidalgo, 54% con la Sierra de Catorce, San Luis Potosí y 50% con el Valle de Tehuacán-Cuicatlán, estados de Puebla y Oaxaca. Existe una mayor afinidad con la zona árida del Valle del Mezquital y en general con la porción sur del Desierto Chihuahuense. Se distinguen cinco asociaciones de matorral: Fouqueria splendens-Agave striata, Mimosa-Myrtillocactus, Opuntia, Opuntia imbricata-Myrtillocactus y Yucca. Debido a la falta de endemismos, los elementos florísticos del matorral xerófilo del Valle de Tecozautla probablemente migraron al área en épocas recientes.

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wetlands are among the most productive ecosystems in the world and contain a high diversity of species. Despite this, wetlands are threatened by human activities because function is affected and some of them even disappear, particularly those in desert areas. Therefore, it is necessary to build simple tools but reliable for assessing the quality of a wetland and that can remark the importance of wetlands for biological groups in order to detect species population trends and to propose conservation strategies of wetlands and their biodiversity. An example is the use of particular species as bioindicators of species richness (e.g. of waterfowl). The Sandhill crane (Grus canadensis) depends on wetlands as wintering refuge sites. This crane is listed as a threatened species in Mexico. The aim of this paper is to analyze whether the Sandhill crane can be considered as an indicator of waterbirds' richness species in order to perform a rapid assessment of any wetland the crane uses. Although a correlation between of the presence of cranes and richness of waterbird species was not found a difference was observed in the composition of species and relatively greater species richness in wetlands where it cranes were present. Wetlands were not similar in species composition, thus cranes can be a useful indicator for different assemblages of waterbirds. Using the bioindicator species analysis the Sandhill crane has a value of 27.5 from a maximum of 32. Therefore, the Sandhill crane can be considered as an indicator of waterbirds species richness in arid wetlands. Long-term studies should be done in order to evaluate the relationships between the abundances of cranes and the total abundance of waterbirds in order to evaluate the quality of wetlands in relation to abundance. [ABSTRACT FROM AUTHOR]

As a megadiverse country, Mexico harbors 4 to 8% of the flora of the world and of this, 51% is endemic. There is concern because several factors are impeding its conservation. In this paper, areas of endemism for the flowering plants of Mexico are identified to prioritize regions for conservation. To categorize zones for preservation, the approach followed takes biodiversity, weighted endemism and evolutionary history into account. Lineages of angiosperms, families, genera, and formal or informal groups within genera previously retrieved as monophyletic are selected to represent evolutionary history in equivalent spatial units. A database with 9416 entries based on specimens of species belonging to 259 monophyletic groups of angiosperms from Mexico was compiled, and their presence-absence recorded for every unit area. Species richness and weighted endemism index was calculated for each of these units. The results indicate that the majority of the regions with the highest indices of endemism have a dry climate with xeric vegetation, with the exception of two areas of tropical and temperate forests. They are: the northeastern rosette scrub in Nuevo León and Coahuila, gypsum grasslands in San Luis Potosí, the Sierra Gorda in Queréraro, Tolantongo in Hidalgo, the Tehuacán-Cuicatlán Valley in Puebla and Oaxaca, El Salto in Durango, Sierra de Quila in Jalisco, a western portion of the Balsas River Basin in Michoacán, Guerrero, Morelos and State of Mexico, the Tehuantepec area in Oaxaca, the Central Depression of Chiapas and El Triunfo in Chiapas. Some of the areas of endemism in the Chihuahuan Desert, Balsas River Basin, the Central Depression of Chiapas and the southern area of Oaxaca are not sufficiently protected. Approximately 340 species were microendemic, i.e. restricted to a single quadrat, and the Cactaceae account for the majority of the species on the Mexican Red List. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Mexican buckeye Ungnadia speciosa, is one of the plants used in forestation programs in Mexico due its adaptive features and its shrub or small tree form; however production in the greenhouse is affected by pathogens that cause leaf blight, dwarf and fork stalks, making it impossible to use in plantations. The objective of this work was to determine the causal agent and evaluation of in vitro and in situ of benzalkonium chloride to control it. Plant tissue was collected in field and greenhouse and put in nutrient agar and potato dextrose agar. LOPAT and relevant biochemical test were conducted for identification. For the incidence and severity, the model proposed by French (1982), was used. The poisoned plate flock was used for the in vitro evaluation with 13 treatments and five repetitions, assessing the colony forming units (CFU); seven in situ treatments with three replications were used evaluating damaged leaf area. It was found that for Pseudomonas syringae, according to the Koch's postulates involved in the symptoms of blight and deformities in the Mexican buckeye, field incidence was 12,9% and 36% in greenhouse; severity was 6,5% and 32%, respectively. Benzalkonium chloride satisfactorily controlled in vitro in dosages, and the best treatment in situ was 3 000 ppm (7 g/L), which showed a leaf damaged area of 17,33% and target treatment 73,09%. [ABSTRACT FROM AUTHOR]

Perturbation on natural predation in a driest year (1988) on eight grasshopper species assembly during an outbreak of one of them (Boopedon nubilum) in a toboso arid grassland in Chihuahuan Desert was analyzed. We used a four blocks trial with a treatment (predators' decreased) and a control. Predators recorded were five mammals, five reptiles, two amphibians, 20 birds, six diurnal Insects, six spiders and four nocturnal arthropods. The vertebrate predators presence (principally raptors) inhibited invertebrate predators action, the most important predators were birds. Results showed no significative effect of date and treatment on grasshopper density (pooled data). The effect of predation on the most abundant grasshopper species (B. nubilum) was observed, changing the species composition of the assembly and the use of plant stratification by grasshoppers. The graminicole species showed an escape strategy of jumping between grasses, tussocks, bunches or to bare soil, or only keep down into the grass, using this strategy, vulnerability (detection risk by predators) depends on their coloration and final position adopted to avoid predators. The short time effect results were due by short time response in treatment add to the predation satiation phenomena by over offer of meal in this specific patch by the outbreak grasshopper species. Where control and treatment showed clearly negative tendency on the population records of B. nubilum and a natural effect of predation, but our statistical analysis showed no significative differences, suggesting it is more adequate to do this kind of trials, considering a larger remotion of predators and monitoring and evaluating on next generation of grasshopper species. [ABSTRACT FROM AUTHOR]

Ecologists and conservationists have long assumed that large grazers, including bison (Bison bison ), did not occur in post-Pleistocene southwestern North America. This perception has been influential in framing the debate over conservation and land use in the northern Chihuahuan Desert. The lack of an evolutionary history of large grazers is being used to challenge the validity of ranching as a conservation strategy and to limit the protection and reintroduction of bison as a significant component of desert grassland ecosystems. Archeological records and historical accounts from Mexican archives from AD 700 to the 19th century document that the historic range of the bison included northern Mexico and adjoining areas in the United States. The Janos-Hidalgo bison herd, one of the few free-ranging bison herds in North America, has moved between Chihuahua, Mexico, and New Mexico, United States, since at least the 1920s. The persistence of this cross-border bison herd in Chihuahuan Desert grasslands and shrublands demonstrates that the species can persist in desert landscapes. Additional lines of evidence include the existence of grazing-adapted grasslands and the results of experimental studies that document declines in vegetation density and diversity following the removal of large grazers. The Janos-Hidalgo herd was formed with animals from various sources at the turn of the 19th century. Yet the future of the herd is compromised by differing perceptions of the ecological and evolutionary role of bison in the Desert Grasslands of North America. In Mexico they are considered native and are protected by federal law, whereas in New Mexico, they are considered non-native livestock and therefore lack conservation status or federal protection. Evidence written in Spanish of the presence of bison south of the accepted range and evidence from the disciplines of archaeology and history illustrate how differences in language and academic disciplines, in addition to international boundaries, have acted as barriers in shaping comprehensive approaches to conservation. Bison recovery in the region depends on binational cooperation. [ABSTRACT FROM AUTHOR]

The Sierra de Catorce located in the north of San Luis Potosí state, shelters some of the most important peaks within the Chihuahuan Desert, whose altitudes reach beyond 3000 meters. The fact that the Sierra is an important area for flora and plant community diversification in this ecoregion has been favoured by this situation. From a phytosociological study of the territory vegetation, carried out since 1999, we have extracted a preliminary checklist of the flora. Until now the vascular plants checklist is composed by 526 species and four infraespecific taxa, assembled in 293 genera and 88 families. The best represented families and genera are Asteraceae, Poaceae, Cactaceae, Fabaceae, Fagaceae, and Lamiaceae, and Quercus, Opuntia, Muhlenbergia, Salvia, Agave, Bouteloua and Dyssodia respectively. The vegetation types representative of the area which shelter the diferent taxa, are indicated. Finally, from different checklists of threatened flora, the species included in some of the recognised categories are identified. [ABSTRACT FROM AUTHOR]

The reproductive cycle of the lizard Uta stejnegeri Schmidt 1921 (previously Uta stansburiana stejnegeri Schmidt 1921) was determined using data obtained from field caught individuals at the Biosphere Reserve of Mapimí, Durango, México. During 1990 monthly samples of this species were collected from sand dunes. Males reached sexual maturity at 45.0 mm snouth-vent length (SVL); females reached sexual maturity at 40.0 mm SVL. The reproductive cycles of both sexes were synchronous. Significant variation in testes mass was determinated by ANCOVA and males reached maximal testes mass between December-February; testes began to decrease in July, reaching minimum mass in September. The monthly percentage of non-vitellogenic follicles, vitellogenic follicles and oviductal eggs was recorded for females. Enlarged vitellogenic follicles first appeared during mid-January in females. These showed bimodal presence of eggs in oviducts between February and May and in July. Mean clutch size based on oviductal eggs counts was 2.8 ± 1.1. Clutch size was positively correlated with female body size. Most of the annual rainfall ocurrs during summer, and we suggest that offspring production is timed to the best season to promote juvenile growth and survivorship. We found similarities between this reproductive cycle and those previously reported for U. stansburiana from the United States. [ABSTRACT FROM AUTHOR]

Ants are considered an important aspect of arid zones mainly due to their role in structuring plant communities and for the diverse interactions they establish with other organisms. However in Mexican arid zones a basic understanding of ant species diversity is lacking. In this study we examined the ant fauna of a locality situated in the semi-desert Tehuacán Valley (San Rafael Coxcatlán). Our objectives were to estimate ant species richness within this region and to obtain a more extensive survey of the Tehuacán Valley by combining our data with another study. Finally we compared the species richness of this Valley to that of other Mexican arid zones (Mapimí, Durango, Chihuahuan Desert and Los Horcones, Sonora, Sonoran Desert). Ants of San Rafael Coxcatlán were collected between November 1999 and January 2001 using pitfall traps. 28 ant species were captured from 14 genera within five subfamilies, which is a high species richness for a small area (5 km²). Based on a cluster analysis, the mirmecofauna of Los Horcones and the Tehuacán Valley were the most similar; both areas have ant species with broad distribution as well as some of tropical affinity such as Pseudomyrmex major and Camponotus atriceps. Similar patterns have been reported for the vegetation, birds and mammals in both areas; several genera are shared, most of them of tropical affinity. This work represents one of the first efforts to understand ant diversity in an arid zone of central Mexico. [ABSTRACT FROM AUTHOR]

Uma paraphygas is an endemic lizard which is in danger of extinction because of its very restricted distribution, low genetic variability, and the high environmental pressure to which it is exposed. Two populations of U. paraphygas were observed in two areas of 2 ha each in the Mapimi Biosphere Reserve, Durango. The field work was carried out from autumn of 1997 to the summer of 1999. The survey was made by the capture-recapture method, using the noose technique. The animals captured were marked permanently. This survey provides information about the structure and dynamics of two populations of this lizard in order to determine its current status. Density, biomass, age structure, growth rates, survival, population replacement rate and generational time of this lizard were determined. Density and biomass changed in relation to acumulated rainfall. There were no significant differences for density and biomass factors between the two populations. The higest percentage of the population was represented by adult females followed by adult males. The highest daily growth rate was for offspring of both sexes which gradually decreased as they grow older. Offspring annual survival was 0.20. However, the lowest survival rate was for subadult females, while the highest one was for subadult males. We suggest that the survival for different age classes is related to intraspecific competition factors. The population replacement rate indicated an apparent stability for the two populations, and the generational time was 1.26 years. [ABSTRACT FROM AUTHOR]

The vegetation and the vascular plants of an ecotonal zone between the floristic provinces of the Desert Plateau (Chihuahuan Desert) and Gulf Coastal Plain in northeastern México were studied. The study zone has a surface of 2,526.25 km² and it is located in the northern part of the state of Nuevo León. On the basis of physiognomy, ecological characteristics and dominant species, seven types of vegetation were recognized. With the aid of 50 sampling plots, aerial photographs and floristic composition, the units of vegetation were delimited and mapped. 405 species (varieties and subspecies included) were identified. The study zone showed geographical affinity with the vegetation of the Chihuahuan Desert in the Desert Plateau of México (Hilaria mutica grassland, low thornless scrub of Flourensia cernua and medium size mixed scrub of Acacia-Prosopis-Flourensia-Larrea) and with the Gulf Coastal Plain (medium size mixed scrub of Leucophyllum frutescens and Acacia rigidula and high mixed scrub of Helietta parvifolia). The medium size and high thorny scrubs of Prosopis-Acacia showed no clear relationships with any of the floristic provinces. The coexistence of shrubby vegetation characteristic of the lowlands in the Gulf Coastal Plain and the vegetation usually present in the Chihuahuan Desert, can be explained in view of the increment of aridity and gentle raising of the continental surface in east-west direction, and of the absence of notable topographic accidents in the northeastern region of México. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) of arid and semiarid ecosystems are important for the development of plants that grow under biotic stress in wild or in agro-ecosystems. There is little information on the temporal diversity of these organisms in perennial plants from arid ecosystems in northern Mexico. On this study, the mycorrhizal colonization and the temporal diversity of AMF in the rhizosphere of Larrea tridentata, perennial plant abundant in the Chihuahuan Desert region were explored. Samples of the rhizosphere and roots of fifteen plants in each of the three sampling dates during the 2015 year were obtained. A total of 17 species of HMA belonging to 12 genera and 7 families within the phylum Glomeromycota in all three sampling dates were found. Funneliformis geosporum was the dominant species belonging to the family Glomeraceae which possess the highest genera number on L. tridentata. The highest mycorrhization percentage was in February with 83.22, followed by September and May with 75.27 and 65.27%, respectively. A maximum of 16 AM fungal species were isolated and identified from L. tridentata rhizosphere in February, 15 species in May and 12 species in September. Statistical analysis showed significant differences between sampling dates in the spores number., (Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)