Chihuahuan Desert Of Mexico Research Articles

New species of flea of the genus Dactylopsylla Jordan (Insecta: Siphonaptera) from the Flora and Fauna Protection Area Mdanos de Samalayuca, Chihuahua, Mexico.

A new species of Dactylopsylla Jordan, parasites of Geomyidae rodents from Chihuahua, is described and illustrated as D. samalayucae n. sp. This species is compared with their morphologically closest relatives. Males are characterized by the shape of the upper lobe of the inmovable and movable process, the shape and chaetotaxy of the distal arm of sternum IX and the shape of the crochet; and females by the contour of the distal margin of sternum VII. The geographical distribution of Dactylopsylla is extended to the Chihuahuan desert in Mexico as D. samalayucae n. sp. is reported from south of the Natural Protected Area Mdanos de Samalayuca (MS). A recent key to Dactylopsylla species is updated with inclusion of the new species.

Geochemical evolution and seasonality of groundwater recharge at water-scarce southeast margin of the Chihuahuan Desert in Mexico

Climate models for the 21st century project further reduction in the warm season precipitation and more frequent droughts across Mexico. In the possible scenario of enhanced aridity from global warming, the δ18O (−10.6 to −6.3 ‰) and δ2H (−71.1 to −57.1 ‰) compositions and deuterium-excess (0.2–14.6‰) of shallow groundwater from two different basins (Sandia and El Potosi) with similar geological and geomorphological settings were considered to evaluate the influences of early summer rainfall and later summer tropical storms on aquifers at water-scarce southeast margin of the Chihuahuan Desert. Groundwater of the Sandia Basin was recharged mainly from tropical storms. Higher CO2 partial pressure (log pCO2: −2.70 to −1.61) caused more gypsum dissolution (Ca–Mg–SO4 facies) and the effect of irrigation return flow (Ca–Mg–Cl facies) was minor. Even though the El Potosi Basin is in proximity, its groundwater was recharged from both the early and late summer precipitations. The multivariate factor analysis helped to separate the process of rock-water interactions from the recharge seasonality. Gypsum dissolution was less as the partial pressure of CO2 was comparatively lower (log pCO2: −3.01 to −2.15), and the ion exchange along with carbonate mineral dissolutions led to Ca–Mg–HCO3 facies. Over-exploitation under the condition of reduced warm season rainfall would continue to enhance the salinity of groundwater in this region. Hence, the drought mitigation policies should prioritize sustainability of the depleted aquifers and cultivation of salinity resistant crops.

Thermoregulation in a saxicolous population of the lizard Urosaurus ornatus from the northern Chihuahuan Desert, Mexico

Abstract Environmental temperatures often regulate the activity and physiological processes of ectotherms. Because environmental temperatures can vary significantly among seasons, lizards exposed to different thermal conditions in different months could differ in how they thermoregulate or behave. Here, we present a combination of field, laboratory, and modeling approaches to examine thermoregulation, habitat thermal quality, and hours of thermal restriction on activity in a saxicolous population of Urosaurus ornatus in two thermally contrasting months (June and October) in a micro-insular mountain system in the northern Chihuahuan Desert in Mexico. Both active and preferred body temperatures did not vary between months. In this population, U. ornatus is an active thermoregulator with highly accurate and efficient thermoregulation despite the thermal quality in both months. However, during the breeding season (June) activity is restricted (i.e., high number of hours of restriction) compared to the non-breeding season (October). Therefore, our results suggest that this saxicolous population of U. ornatus could be threatened by global climate change and it is essential to determine a conservation strategy for this population.

Winter Diet and Prey Availability of the Long-Billed Curlew (Numenius americanus) in the Chihuahuan Desert, Mexico

The long-billed curlew (Numenius americanus) is a species of international conservation concern. Effective long-term conservation measures for a species require knowledge of all aspects of the species' ecology within its range. We analyzed 210 pellets regurgitated by long-billed curlews that were collected at two sites in the Chihuahuan Desert in Mexico. From these pellets, we identified 34 prey items corresponding to three classes of invertebrates (10 orders, 18 families, and 9 morphospecies), one class of reptiles (one order and one family), one class of plants (one order, one family, and four morphospecies), as well as gastroliths. We selected three habitat types used by the curlews and conducted a prey availability analysis with pitfall traps and a sweep net; we estimated a biomass of 20.78 g of ground-dwelling invertebrates and 64.73 g of flying and foliage invertebrates for every 10 m2 during the winter season. Our results demonstrate that the long-billed curlew has high dietary flexibility and uses different habitats during its wintering stay in the Chihuahuan Desert in Mexico. One main threat was detected on wintering grounds: exposure to pesticides, which can lead to both physiological problems and the reduction of its main prey.

In vitro anticancer activity of methanolic extract of Granulocystopsis sp., a microalgae from an oligotrophic oasis in the Chihuahuan desert

With the purpose of discovering new anticancer molecules that might have fewer side effects or reduce resistance to current antitumor drugs, a bioprospecting study of the microalgae of the Cuatro Cienegas Basin (CCB), an oasis in the Chihuahuan desert in Mexico was conducted. A microalgae was identified as Granulocystopsis sp. through sequencing the rbcL gene and reconstruction of a phylogenetic tree, and its anticancer activities were assessed using various in vitro assays and different cell lines of human cancers, including lung, skin melanoma, colorectal, breast and prostatic cancers, as well as a normal cell line. The values of IC50 of the microalgae methanolic extract using the MTT assay were lower than 20 μg/ml, except that in the lung cancer line and the normal cell line. In vitro, the microalgae extract caused the loss of membrane integrity, monitored by the trypan blue exclusion test and exhibited marked inhibition of adhesion and cell proliferation in cancer cell lines, through the evaluation of the clonogenic assay. Also, typical nuclear changes of apoptotic processes were observed under the microscope, using the dual acridine orange/ethidium bromide fluorescent staining. Finally, the microalgae extract increased the activity of caspases 3 and 7 in skin melanoma, colon, breast and prostate cancer cells, in the same way as the apoptotic inductor and powerful antitumoral drug, doxorubicin. This study shows the anticancer activity from Granulocystopsis sp., a microalgae isolated from the CCB.

Soil deterioration in the southern Chihuahuan Desert caused by agricultural practices and meteorological events

In arid and semi-arid regions, unregulated land use changes as a result of poor planning, and the expansion of agricultural and livestock activities increase the risk of desertification and other potentially severe environmental impacts. Several consequences of improper land management practices are soil deterioration and erosion, which may be intensified by meteorological events. This paper presents a historical evaluation of the temporal and spatial evolution of soil deterioration in the southern Chihuahuan Desert in Mexico. A multi-temporal analysis of the study area during the 1995–2016 period was carried out using satellite data (Landsat series). Two seasons were analyzed to determine the influence of external events such as rainfall and wind: dry and rainy. The identification of soil conditions was based on the Brightness Index (BI) considering the complete satellite data set. The soil conditions were classified into five categories according to their reflectance values: highly deteriorated, deteriorated, in the process of being deteriorated, in good condition and other (clouds, water, non-soil). The change detection maps clearly show a growing trend wherein areas of deteriorated and eroded soil increase over time. Agriculture and strong winds are the two main factors involved in the soil deterioration process of the study region.

The history of Aplomado Falcon Falco femoralis subspecies diagnoses

I present the historical details associated with early 20th century descriptions of Aplomado Falcon subspecies. I identify potential weaknesses in these diagnoses that justify re-examination of traditional taxonomy, and stress that climate change, habitat modification and large-scale reintroduction efforts may have altered or eliminated any valid subspecies boundaries that once existed. I recommend that conservation efforts in the Northern Hemisphere focus on the Chihuahuan Desert of Mexico where Aplomado Falcons have declined severely in recent years.

Actinobacteria phylogenomics, selective isolation from an iron oligotrophic environment and siderophore functional characterization, unveil new desferrioxamine traits.

Desferrioxamines are hydroxamate siderophores widely conserved in both aquatic and soil-dwelling Actinobacteria. While the genetic and enzymatic bases of siderophore biosynthesis and their transport in model families of this phylum are well understood, evolutionary studies are lacking. Here, we perform a comprehensive desferrioxamine-centric (des genes) phylogenomic analysis, which includes the genomes of six novel strains isolated from an iron and phosphorous depleted oasis in the Chihuahuan desert of Mexico. Our analyses reveal previously unnoticed desferrioxamine evolutionary patterns, involving both biosynthetic and transport genes, likely to be related to desferrioxamines chemical diversity. The identified patterns were used to postulate experimentally testable hypotheses after phenotypic characterization, including profiling of siderophores production and growth stimulation of co-cultures under iron deficiency. Based in our results, we propose a novel des gene, which we term desG, as responsible for incorporation of phenylacetyl moieties during biosynthesis of previously reported arylated desferrioxamines. Moreover, a genomic-based classification of the siderophore-binding proteins responsible for specific and generalist siderophore assimilation is postulated. This report provides a much-needed evolutionary framework, with specific insights supported by experimental data, to direct the future ecological and functional analysis of desferrioxamines in the environment.

Genetic diversity of sotol (Dasylirion cedrosanum Trel.) at different elevations

Genetic analysis is important to identify genetic variability in organisms inhabiting a speci c region. In this study, a sotol population was characterized through ve elevational levels at one location in the Chihuahuan Desert in Mexico, using ampli ed fragment length polymorphisms (AFLP) markers. Population genetic diversity, polymorphic loci, Nei's unbiased heterozygosity, average and e ective number of alleles, and optimum number of samples were determined. A dendrogram was constructed, and Shannon entropy was calculated. Based on the estimated parameters, the middle elevational level had the highest genetic variation. The optimum sample size to determine genetic variability in sotol was from 24 to 26 plants. In the produced dendrogram, no association was observed among plants belonging to the same stratum, which could be explained by the high genetic ow among plants from di erent strata. These results provide a foundation of knowledge for understanding the genetic diversity in sotol populations growing in the Chihuahuan Desert mountains. The information will allow designing strategies for implementing sotol breeding and conservation programs.

Species delimitation of the blue-spotted spiny lizard within a multilocus, multispecies coalescent framework, results in the recognition of a new Sceloporus species

Species delimitation is a major topic in systematics. Species delimitation methods based on molecular data have become more common since this approach provides insights about species identification via levels of gene flow, the degree of hybridization and phylogenetic relationships. Also, combining multilocus mitochondrial and nuclear DNA leads to more reliable conclusions about species limits. Coalescent-based species delimitation methods explicitly reveal separately evolving lineages using probabilistic approaches and testing the delimitation hypotheses for several species. Within a multispecies, multilocus, coalescent framework, we were able to clarify taxonomic uncertainties within S. cyanostictus, an endangered lizard that inhabits a narrow strip of the Chihuahuan Desert in Mexico. We included, for the first time in a phylogenetic analysis, lizards from the three populations of S. cyanostictus recognized so far (East Coahuila, West Coahuila and Nuevo León). Phylogenetic analysis corroborates the hypothesis of two separately evolving lineages, i.e. the East and West Coahuila populations, as proposed in a previous study. We also found a distant phylogenetic relationship between the lizards from Nuevo León and those of East and West Coahuila. Finally, based on the species delimitation results, we propose and describe a new species of Sceloporus: S. gadsdeni sp. nov.

Using Range-Wide Abundance Modeling to Identify Key Conservation Areas for the Micro-Endemic Bolson Tortoise (Gopherus flavomarginatus).

A widespread biogeographic pattern in nature is that population abundance is not uniform across the geographic range of species: most occurrence sites have relatively low numbers, whereas a few places contain orders of magnitude more individuals. The Bolson tortoise Gopherus flavomarginatus is endemic to a small region of the Chihuahuan Desert in Mexico, where habitat deterioration threatens this species with extinction. In this study we combined field burrows counts and the approach for modeling species abundance based on calculating the distance to the niche centroid to obtain range-wide abundance estimates. For the Bolson tortoise, we found a robust, negative relationship between observed burrows abundance and distance to the niche centroid, with a predictive capacity of 71%. Based on these results we identified four priority areas for the conservation of this microendemic and threatened tortoise. We conclude that this approach may be a useful approximation for identifying key areas for sampling and conservation efforts in elusive and rare species.

Helminth parasites of freshwater fishes from Cuatro Ciénegas, Coahuila, in the Chihuahuan Desert of Mexico: inventory and biogeographical implications.

As part of an ongoing inventory of the helminth parasites of freshwater fishes in Mexico, 570 individual fish were collected between Apr 2008 and Oct 2011 in 26 localities along the Cuatro Ciénegas region in Coahuila State, northern Mexico. Seventeen species of hosts, mostly corresponding to Nearctic freshwater elements, were studied. A total of 8324 individual worms were collected during this survey, representing 25 species of helminths, of which 9 were digeneans, 3 monogeneans, 3 acanthocephalans, 9 nematodes and 1 cestode. Most of the records in this checklist represent new host or locality records. The information provided in this checklist may be helpful for our understanding of the biodiversity and historical biogeography of this host-parasite system, because in the Cuatro Ciénegas region occur a Nearctic freshwater fish fauna, along with Neotropical and endemic elements, and from a biogeographical point of view, this may represent a transitional area.

Home range and habitat use of wintering Vesper Sparrows in grasslands of the Chihuahuan Desert in Mexico

Abstract Grassland birds are declining at an alarming rate and habitat limitation on the wintering grounds may play a major role in population declines. In an attempt to understand habitat needs and constraints of grassland bird species on their wintering grounds, we conducted the first-ever telemetry study to document the movements of a wintering grassland passerine bird in grasslands of the Chihuahuan Desert in northern Mexico. We attached radio-transmitters to 99 Vesper Sparrows in January of 2009 and 2010 and tracked them for up to 51 days. We estimated vegetation characteristics at foraging, roosting and random locations. We used kernel density estimators of the utilization distribution for each individual sparrow to estimate home range size. We found differences in average home range size between 2009 and 2010 (108.46 ± 36.43 ha and 30.91 ± 4.74 ha, respectively). Home ranges showed high levels of intraspecific overlap, with average pairwise overlap of 0.41, 0.70 and 0.79 among individuals at three ...

Home Range Size and Activity Patterns of Bobcats (Lynx rufus) in the Southern Part of their Range in the Chihuahuan Desert, Mexico

Abstract Home range size, daily travel distances, and diel activity patterns are important characteristics of how an animal uses its home range area. In species, such as the bobcat (Lynx rufus), with large geographical ranges, it is necessary to gather data on diverse populations across the range to better understand what might be factors influencing these home range parameters. Although there are many studies of bobcats in more northern areas of its range in the United States, few data exist from its extensive southern range in Mexico. To fill this gap in information, we collected data on home range size, daily travel distances, and diel activity patterns of bobcats from the center of the Chihuahuan Desert in Mexico. We compared our findings with available data from more northern studies and tested for any latitudinal trends in home range size. We trapped eight adult bobcats (four females and four males) between 2006 and 2008 at the Mapimi Biosphere Reserve in the Chihuahuan Desert. Each bobcat was equip...

In Vitro Conservation ofTurbinicarpus(Cactaceae) Under Slow Growth Conditions

The current work describes an in vitro conservation technique employing slow growth conditions in 16 threatened species and subspecies of the genus Turbinicarpus (Cactaceae), all native to the Chihuahuan Desert in Mexico. It was demonstrated that the addition of osmotic agents like mannitol (30 g L-1) and sorbitol (30 g L-1) to the culture medium, as well as low-temperature incubation (4 ± 0.5 °C), are able to reduce the in vitro growth rate without affecting the viability of shoots subjected to these treatments. The material that was kept under the aforementioned treatment conditions for 12 months was able to regenerate shoots through areole activation when transferred to media containing cytokinins. These shoots are able to root, and the generated plants can adapt and survive in soil, with similar efficiencies to those that were not subjected to slow-growth treatment. With this methodology it is possible to maintain a bank of viable tissues of these species in vitro, with minimal maintenance and the possibility of obtaining complete plants whenever required.

Spatial patterns of grasses and shrubs in an arid grassland environment

In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and can provide information on grass shrub interactions. To better understand the dynamics of the Chihuahuan Desert ecosystem and to provide information regarding the interactions between grasses and shrubs, we examined the spatial patterns of grasses and shrubs in remaining grass-dominated areas, interspersed with some shrubs. We developed 18, 10 × 20 m vegetation distribution plots by mapping the location of all grasses and shrubs on each and repeating the measurements three years later. Spatial patterns were then assessed for each plot using a second-order spatial statistic, Ripley's K-function, as well as any observed changes in the spatial patterns over a three-year period. We observed clumped grass distributions, indicating a lack of competition among grasses; random shrub distributions; and even grass distribution with respect to shrub locations, indicating competition between grasses and shrubs. We also observed a tendency for grass distributions to become more even over time, and grasses to become less even with respect to shrub locations over time. These changes occurred during a period of greater than average rainfall, indicating that greater water availability may lead to increased competition among grasses and decreased competition between grasses and shrubs.

Plant productivity, predation, and the abundance of black-tailed jackrabbits in the Chihuahuan Desert of Mexico

The abundance of black-tailed jackrabbits ( Lepus californicus) can fluctuate dramatically. We used data from the Chihuahuan Desert to test the relative strength of top-down (predation) or bottom-up (food availability) limiting forces. Predictions for the top-down hypothesis were, 1) a positive relationship between coyote ( Canis latrans) and jackrabbit abundance (numerical response) and 2) a positive relationship between percent occurrence of jackrabbits in coyote scats and jackrabbit abundance (functional response). Predictions for the bottom-up hypothesis were, 1) plant productivity is directly related to precipitation, 2) jackrabbit abundance is positively related to precipitation and plant productivity, and 3) changes in abundance of jackrabbits over the reproductive season will be directly related to precipitation and plant productivity. We found a limited numerical response but no functional response of coyotes to jackrabbit abundance. Forb productivity was significantly related to annual precipitation levels ( r 2 = 0.69, p = 0.002). Grass productivity was related to annual precipitation ( r 2 = 0.34, p = 0.028). Jackrabbit abundance ( r 2 = 0.38, p = 0.002) and changes in abundance ( r 2 = 0.73, p < 0.001) were significantly related to precipitation and forb and grass productivity. We conclude that precipitation levels and plant productivity affect jackrabbit abundance more than predation levels.

Precipitation impacts on mule deer habitat use in the chihuahuan desert of Mexico

In arid lands, food resources and predation risk become major decision factors in mule deer habitat use. We examined variables related to these two factors that might determine mule deer ( Odocoileus hemionus) habitat use in a warm desert at two spatial scales: the macro-habitat scale, which relates to home range decisions, and the micro-habitat scale, which relates to decisions made during foraging. Our prediction was that habitat use should primarily be explained by food variables and, to a lesser degree, by variables related to predation risk by pumas ( Puma concolor). We mapped all deer pellet groups in 72, 1 ha quadrats in the Mapimí Biosphere Reserve and measured food and habitat variables over two years with different precipitation amounts. The area was used more intensively during the dry year. Under drier conditions, deer habitat use was explained primarily by food resource variables and secondarily by variables related with predation risk. During the wetter year, food resources became unimportant while cover and visibility explained deer habitat use. The data suggest that the tradeoffs deer are willing to make between food resources and predation risk in an arid environment are strongly affected by food resource levels, as influenced by precipitation.

Candy Barrel Cactus (Echinocactus platyacanthus Link &amp; Otto: A Traditional Plant Resource in Mexico Subject to Uncontrolled Extraction and Browsing

Candy Barrel Cactus (Echinocactus platyacanthusLink & Otto [C Mex.]): A Traditional Plant Resource in Mexico Subject to Uncontrolled Extraction and Browsing. The candy barrel cactus (Echinocactus platyacanthus) is an endemic of the Chihuahuan Desert in Mexico that is used as an ornamental plant, for fodder, and for human consumption. The uncontrolled use of this species has resulted in its being put under special legal protection. Although now illegal to harvest, many candy barrel cacti continue being destroyed in situ by both gathering and livestock grazing. This study describes the uses of this species and the characteristics of its natural population in central Mexico. In order to estimate density, percentage of damaged cactus, and height of candy barrel cactus, censuses were carried in stands of 2,500 m2. The anthropogenic disturbance in each site was estimated by an environmental disturbance index (DI). Results show that the state of Hidalgo has the best conserved population (mean density = 1,111 ind/ha, stratus height = 137 cm, and only 2% of the total cacti injured). Populations in Puebla represent an intermediate state of conservation, while Queretaro has populations with the lowest density (435 ind/ha), the shorter height (62 cm), the highest foraging (18%), and the greatest DI (71.30). We recommend that conservation strategies for this species be implemented immediately, and that areas be established that exclude livestock and prevent extraction by humans.

The phylogenetic placement of the rare North American band-winged grasshopper Shotwellia isleta Gurney, 1940 (Orthoptera: Acrididae: Oedipodinae)

Abstract The phylogenetic placement of the North American band-winged grasshopper Shotwellia isleta (Gurney 1940) (Orthoptera: Acrididae: Oedipodinae) has been investigated. This rare and unique species of grasshopper belongs to a monotypic genus known only from a few isolated locations in the Chihuahuan Desert of Mexico and New Mexico, USA. The taxonomic status of Shotwellia has been uncertain and historically classified in very different ways relative to other genera. We conducted the first molecular phylogenetic cladistic analysis of Shotwellia and of the Chortophaga (Saussure) genus group in which it is currently classified, using three mitochondrial genes (16S, 12S and cytochrome c oxidase II), 14 morphological characters and two behavioral characters. Our analysis supports the current monotypic status of the genus Shotwellia within the Chortophaga genus group and indicates that Shotwellia is sister to the other genera in that group. Shotwellia isleta is a species of conservation concern, and our field sampling indicates that it is a rare specialist of freshwater ephemeral desert lake beds that are being impacted by human activity. Understanding the phylogeny of S. isleta provides a basis from which biological, evolutionary and conservation inferences can be made.