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Sceloporus variabilis is a species of wide distribution and occupies different types of habitat. This paper reports new data on the consumption of lizards, both in tropical and cloud forests, and confirms the occurrence of cannibalism.

The niche comprises the set of abiotic and biotic environmental conditions in which a species can live. Consequently, those species that present broader niches are expected to be more tolerant to changes in climatic variations than those species that present reduced niches. In this study, we estimate the amplitude of the climatic niche of fourteen species of rattlesnakes of the genus

espanolEl declive de la diversidad de especies dulceacuicolas es un fenomeno mundial, pero es especialmente pronunciado en las regiones aridas como en el Desierto Chihuahuense de Coahuila y Durango, norte-centro de Mexico. Existen pocos datos historicos sobre la distribucion y ninguna informacion sobre extinciones de gasteropodos dulceacuicolas mexicanos. En tales casos, los datos paleontologicos pueden ser muy utiles y, a menudo, son la unica forma de documentar las distribuciones pasadas y los eventos locales de extincion u extirpacion. Este nuevo enfoque paleoecologico, llamado Paleobiologia de Conservacion, puede proporcionar perspectivas importantes para los esfuerzos de conservacion de ecosistemas analogos recientes. El sitio de estudio contiene depositos fosiles (Holoceno Tardio) del Distrito Laguna, un area pequena en Coahuila y Durango. De estos depositos fosiles describimos una nueva especie y reportamos varios registros nuevos de gasteropodos cochliopidos, hidrobidos, planorbidos y neritidos. La mayoria de estas especies y algunos generos no se conocen como fosiles de Mexico y todos ellos desaparecieron en tiempos muy recientes. En conjunto con datos de nuestros estudios paleomalacologicos anteriores, presentamos aqui un ejemplo de una extirpacion local “silenciosa” en el norte de Mexico la cual comenzo en el Holoceno Medio. Esta perdida de especies aumento rapidamente en la segunda mitad del siglo XX. De las 32 especies de caracoles dulceacuicolas presentes en el area de estudio durante el Holoceno, solo 4 (12.5%) aun existen. Al menos 24 (75.0%) de ellos desaparecieron del area en el siglo XX debido a la perdida de habitat causada por actividades antropogenicas. Nuestros resultados muestran que especialmente los hidrobidos con intervalos geograficos pequenos (especies endemicas locales) son altamente sensibles y vulnerables a tales acontecimientos de extirpacion. La extirpacion de los caracoles dulceacuicolas en el area de estudio ocurrio silenciosamente (sin registros), mientras que al mismo tiempo unos doscientos kilometros mas al norte, uno de los mayores focos de diversidad de gasteropodos en America del Norte permanecio en la cuenca de Cuatrocienegas. Las mismas amenazas que llevaron a la extirpacion local en nuestra area de estudio aun amenazan a las comunidades de caracoles dulceacuicolas del valle de Cuatrocienegas. EnglishThe decline of freshwater species diversity is a worldwide phenomenon but it is especially pronounced in arid regions such as in the Chihuahuan Desert of Coahuila and Durango, Northern Mexico. There are few historical data on the distribution but no data on extinctions of Mexican freshwater gastropods. In such cases, paleontological data can be very helpful and are often the only way to document past distributions and local extinction or extirpation events. This new paleoecological approach, called Conservation Paleobiology, can provide important perspectives in favor of conservation of recent analogue ecosystems. The study site contains subfossil (Late Holocene) deposits of the Laguna District, a small area in Coahuila and Durango. Here we describe a new species and report several new records of subfossil cochliopid, hydrobid, planorbid and neritid gastropods. Most of these species (and some genera) have not been known as fossil from Mexico and all of them disappeared in very recent times. Together with data from our former paleomalacological studies, we present herein an example of a “silent” local extirpation in northern Mexico that began in the Middle Holocene. This loss of species apparently increased rapidly in the second half of the 20th century. Of 32 species of freshwater snails present in the area of study through the Holocene only four (12.5%) are still extant. At least 24 (75.0%) of them disappeared from the area in the 20th century due to habitat loss caused by anthropogenic activities. The results show that especially hydrobiid species with small geographic ranges (local endemics) are highly sensitive and vulnerable to such extirpation events. In this study area the extirpation of freshwater snails happened silently (unrecorded) while at the same time some two hundred kilometers farther north, one of the greatest recent hotspots of gastropods diversity in North America remained in the Cuatrocienegas Basin. The same imperilment that led to local extirpation in the area of study still threatens the freshwater snail communities of the Cuatrocienegas valley.

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>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.

Background Studies in Mexico have shown that the genus Pine has always been under evolutionary changes, however currently they have accelerated as a result of human activities. Pinus greggii is a species restricted by particular environmental conditions of the Sierra Madre Occidental, which is of socio-economic importance in terms of wood production and provides environmental services to the ecosystem. Species distribution models are a relevant geospatial tool in decision making, and notable applications exist such as identifying areas of distribution and zones susceptible to climate change. The objectives of this study were: 1) model and quantify the current distribution, and possible future distribution under four scenarios of climate change; 2) identify the most relevant environmental variables that drive changes in distribution; and 3) to propose adequate zones for the species’ conservation in Mexico. Methods 438 records of Pinus greggii from several national and international databases were obtained, and were cleaned up to get rid of duplicates and overestimations in the models. Climatic, edaphic, and topographic variables were used and were generated 100 distribution models for current and future scenarios with Maxent software. Results The model one under replicated of crossvalidation had the best statistic, with an area under the curve of 0.88 and 0.93 for model training and validation, respectively, a partial ROC of 1.94, and a significant Z test (p Pinus greggii in Mexico was 617,706.04 ha and the most important environmental variables for current distribution were the annual mean temperature, mean temperature of coldest quarter, and slope. For the 2041–2060 models, annual mean temperature, precipitation of coldest quarter, and slope were most important. The future models (2041–2060) predict a decrease in suitable habitat for the species from 48,403.85 (7.8%; HadGEM2-ES RCP 8.5 model) to 134,680.17 ha (21.8%; CNRM-CM5 RCP 4.5). Conclusions The spatial modeling of current and future conditions of the ecological niche of Pinus greggii in this study allows the proposal of two zones for conservation purpose and in situ restoration for the species in northeastern (Nuevo Leon) and central (Hidalgo) Mexico.

The industrial production and commercialization of distilled beverages from Sotol plants (Family: Asparagaceae, Subfamily: Zolinoideae and Genus: Dasylirion) has witnessed a steady growth in recent decades, this condition involves a greater use of the raw material that comes almost exclusively from natural populations, which could compromise the sustainability of the marginalized areas of Northern M&eacute, xico. In the present work, habitat availability was evaluated for the presence and use of the species, Dasylirion wheeleri (S. Watson ex Rothr.), Dasylirion cedrosanum (Trelease), and Dasylirion durangense (Trelease) in M&eacute, xico, considering different scenarios of climate change. For this purpose, we used the niche&rsquo, s spatial analysis from a correlative approach. The results show that under the current climate, the species studied have a predominantly low habitat suitability in the central region of the Chihuahuan desert, with D. cedrosanum being the species with the lowest suitability. For the year 2050, a slight increase in the habitat suitability is expected only for D. durangense and D. wheeleri. This suggests that D. cedrosanum could be considered as the species with the greatest vulnerability to the possible climatic variations generated by global climate change. Likewise, the analysis of the results indicates that D. durangense is the one who has the greatest potential for use, however, it is necessary to consider that many of its populations may be climatically stressed and an inappropriate use could put them at risk.

The malacofauna of the Sabinas River, Don Martin basin, Coahuila, North Mexico, was studied conchologically at nine sites. In total, 23 species of freshwater molluscs, of which 21 are native and two invasive, were found. Nineteen species are gastropods and four species bivalves. One genus and two species of subterranean (interstitial) gastropods are endemic to the area and with Lyogyrus sp. we reported for the first time a member of the family Amnicolidae in Mexico. Mexithauma quadripaludium Taylor, 1966, and Juturnia coahuilae (Taylor, 1966) (Cochliopidae), previously known only as endemics from the neighboring Cuatro Ciénegas basin, were found for the first time living out of this basin.

We present an updated checklist of native Mexican freshwater gastropods with data on their general distribution, hotspots of endemicity, threats, and for the first time, their estimated conservation status. The list contains 193 species, representing 13 families and 61 genera. Of these, 103 species (53.4%) and 12 genera are endemic to Mexico, and 75 species are considered local endemics because of their restricted distribution to very small areas. Using NatureServe Ranking, 9 species (4.7%) are considered possibly or presumably extinct, 40 (20.7%) are critically imperiled, 30 (15.5%) are imperiled, 15 (7.8%) are vulnerable and only 64 (33.2%) are currently stable. With 61 species in 21 genera, the Cochliopidae are the most diverse family, followed by the Planorbidae (37 species) and Pachychilidae (31). Pachychilus is the most species-rich genus with 30 species. Despite the high number of imperiled species (84), only 7 species (3.6%) are currently listed as endangered by the Mexican Secretariat of Environment and Natural Resources. We identified 3 hotspots and 2 potential centers of gastropod endemicity. Our research serves as a first step for determining priority areas for conservation of imperiled Mexican freshwater gastropods.

ResumenLa tortuga del Bolsón Gopherus flavomarginatus permanece gran parte de su vida dentro de sus madrigueras. Mediante el estudio de las características del hábitat necesarias para la construcción de sus refugios se pueden obtener modelos de nicho potencial relacionados directamente con la presencia de esta especie. En una localidad de la Reserva de la Biosfera de Mapimí con características típicas del hábitat de G. flavomarginatus se analizó el patrón de dispersión, densidad, elevación, edafología, vegetación, aspecto y pendiente de 151 madrigueras registradas. Se desarrollaron modelos de nicho potencial de las madrigueras con los programas Maxent y ArcMap. Se registraron 2 zonas grandes de alta probabilidad de madrigueras, 1 localizada al oeste de la reserva y la otra al este. El modelo propuesto en este trabajo muestra que las poblaciones de G. flavomarginatus construyen sus madrigueras en zonas que bordean los grandes escurrimientos fluviales y que se distribuyen de una manera agrupada a lo largo de la reserva. Con los modelos generados en este estudio se podrán ajustar las áreas en que se presenta el hábitat necesario para la construcción de madrigueras de G. flavomarginatus. El manejo adecuado y conservación de esas áreas beneficiará directamente la propia conservación de la especie.AbstractBolsón tortoises, Gopherus flavomarginatus, spend much of their lives in burrows. Understanding the habitat characteristics where they construct their burrow shelters is necessary to develop potential niche models identifying constraints that may influence the distribution of this species. We analyzed dispersion pattern, density, elevation, soil, vegetation, slope, and the aspect of 151 registered G. flavomarginatus burrows at the Reserva de la Biosfera de Mapimí. Potential burrow niche models were developed with Maxent and ArcMap software. There were 2 large areas of high probability for burrows, 1 located west and the other to the east of the reserve. The models developed in this study showed that G. flavomarginatus populations tended to build their burrows in areas bordering the large pluvial deposition extents and have a clustered distribution along the Reserve. Models generated in this study should work to identify critical habitat areas required for G. flavomarginatus to construct burrows. The proper management and conservation of these areas will directly benefit the conservation of this species.

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.