Espectro trófico del bagre Ictalurus punctatus (Siluriformes: Ictaluridae), en la presa Lázaro Cárdenas, Indé, Durango, México

Having the objective of determining their trophic spectrum and their variations within a year, the contents of 240 stomachs of Ictalurus punctatus (Rafinesque, 1818) were analyzed from 2006 to 2007. The items of the stomach contents were determined to the order level. The data was analyzed by different quantitative and qualitative methods. The most frequent orders were Perciforms and Atheriniforms corresponding to forage fish, along with green algae of the Charales order. Also, seven orders of invertebrates were found:  Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera and Scorpionida, and two orders of plants: Poales and Fabales. The Perciform order made up almost half of the total weight of the stomach contents, followed by the Atheriniform and the Charales orders. The greatest number of empty stomachs showed up during summer and winter, while the greatest number of filled-up stomachs was found during the spring season. The quantity of food consumed during winter time was significantly lower than the amount consumed during all other seasons. The kind of food consumed during the spring, summer and autumn was mainly fish, while algae were preferred during the winter season.Se analizó el contenido de 240 estómagos de Ictalurus punctatus (Rafinesque, 1818), colectados de 2006 a 2007, con el objetivo de determinar su espectro trófico, su variación por talla y época climática. Los contenidos estomacales se analizaron en laboratorio y los organismos se determinaron hasta nivel de orden. Los datos obtenidos fueron analizados por métodos cuantitativos y cualitativos. Los órdenes más frecuentes fueron Perciformes y Atheriniformes que corresponden a peces forraje, así como algas verdes del orden Charales. Además, se encontraron otros siete órdenes de invertebrados: Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera y Scorpionida, además de dos órdenes de plantas: Poales y Fabales. El orden Perciforme constituyó casi la mitad del total del peso del contenido estomacal, seguido por los órdenes Atheriniforme y Charales. En las estaciones de verano e invierno se presentó el mayor número de estómagos vacíos, mientras que en primavera se encontró el mayor número de estómagos llenos. La cantidad de alimento ingerida en la estación de invierno fue significativamente menor que en las demás estaciones. El principal alimento en primavera, verano y otoño, fueron los peces, mientras que en invierno hubo mayor preferencia por las algas

Análisis del nicho climático de Coryphantha durangensis (Runge ex Schum.) Britton y Rose, 1923 e identificación de zonas potenciales para su conservación ante el cambio climático

Coryphantha durangensis it is an endemic cactus that lives in Mexico, in the center of the Chihuahuan desert, and is considered as Special Protection by the NOM-059-SEMARNAT-2010 One of the greatest threats to this species is climate change and habitat loss. In the present study, the climatic niche of C. durangensis was evaluated and the habitat availability of this species was modeled using the MaxEnt algorithm under current climate conditions and future. The results show a reduction in the geographical areas that present climatically suitable conditions for the presence of this species for the year 2050 and 2070, however, four sites were identified that could be proposed as conservation areas for this and other species that cohabit in these zones.Coryphantha durangensis es una cactácea endémica que habita en México, en el centro del desierto Chihuahuense, y está considerada en la categoría de Protección Especial por la NOM-059-SEMARNAT-2010. Una de las mayores amenazas para esta especie es el cambio climático y pérdida de idoneidad climática para su presencia, en el presente estudio se evaluó el nicho climático de C. durangensis y se modeló la disponibilidad climática de esta especie mediante el algoritmo MaxEnt bajo condiciones del clima actual y futuro. Los resultados muestran una reducción en las zonas geográficas que presentan condiciones climáticamente adecuadas para la presencia de esta especie para el año 2050 y 2070. Sin embargo, se identificaron cuatro sitios que podrían ser propuestos como áreas de conservación para ésta y otras especies que cohabitan en estas zonas

Shifts in Climatic Niche Occupation in <i>Astrophytum Coahuilense</i> (H. Möller) Kayser and Its Potential Distribution in Mexico

It has frequently been reported that species with strong niche conservatism will not be able to adapt to new climatic conditions, so they must migrate or go extinct. We have evaluated the shifts in climatic niche occupation of the species Astrophytum coahuilense and its potential distribution in Mexico. We understand niche occupation as the geographic zones with available habitats and with the presence of the species. To assess shifts in climatic niche occupation, we used niche overlap analysis, while potential distribution modeling was performed based on the principle of maximum entropy. The results indicate that this species presents a limited amplitude in its climate niche. This restriction of the climatic niche of A. coahuilense limits its ability to colonize new geographical areas with different climatic environments. On the other hand, the potential distribution models obtained from the present study allow us to identify potential zones based on the climatic requirements of the species. This information is important to identify high priority areas for the conservation of A. coahuilense

Feeding ecology of the catfish Ictalurus punctatus (Siluriformes: Ictaluridae) in a reservoir in Northeast Mexico

Objective: Determine the main food components of the catfish, their seasonal variability and according to the sex of the organism. Methodology: In total, 143 stomachs of catfish were examined. In the analysis of the stomach content, the detected organisms were determined until the taxonomic order rank. It was analyzed the seasonal and sex feeding variability. Results: The total annual trophic spectrum for catfish consisted of 13 items, of which only the order Ephemeroptera reached the category as a frequent food. In the winter season the catfish consumed significantly more food compared to the other seasons and there was no difference in the amount consumed by females and males (p&gt;0.05). Implications: This information is relevant to highlight the importance of the biological integrity of the terrestrial site surrounds the reservoir, which is a source of food for the catfish. Conclusions: Catfish channel in the Venustiano Carranza Dam is a generalist species (13 alimentary items). There was a difference in the amount of food consumed between the seasons of the year; however there was no difference between the sexes.Objective: To determine the main food of the catfish according to seasonal variability and the sex of theorganism in the Venustiano Carranza Dam, Coahuila, Mexico.Methodology: In total, 143 catfish stomachs from different seasons were examined. In the analysis of the stomach content, the detected organisms were determined until the taxonomic order rank. The seasonal and sex feeding variability were also analyzed. The Relative Importance Index and the Alimentary Index were applied. Non-parametric tests were carried out to compare stomach content between seasons and sexes.Results: The total annual trophic spectrum for catfish consisted of 13 items, of which only the order Ephemeroptera was categorized as a frequent food. In the winter season the catfish consumed significantly more food compared to the other seasons, but there was no difference in the amount consumed by females and males (p&gt;0.05).Implications: This information is relevant to highlight the importance of the biological integrity of the terrestrial site which surrounds the reservoir as a source of food for the catfish.Conclusions: Catfish channel in the Venustiano Carranza Dam is a generalist species (13 alimentary items). There was a difference in food consumed during the different seasons of the year. However, there was no difference between the sexes