Search Results (85)

Bifacial photovoltaic technology is made up of solar cells with the ability to generate electrical power on both sides of the cell (front and rear), consequently, they generate more energy in the same area compared to conventional or monofacial solar cells. The present work deals with the calculation of the energy yield using bifacial solar cells under the specific environmental conditions of Tampico, Tamaulipas, Mexico. Two configurations were compared: (1) tilted, optimized in height and angle, oriented to the south, and (2) vertically optimized in height, oriented east–west. The results were also compared with a standard monofacial solar cell optimally tilted and oriented south. The experimental data were acquired using a current–voltage (I-V) curve tracer designed for this purpose. This study shows that the vertically optimized bifacial solar cell produces similar electrical power to the conventional monofacial solar cell, with the benefit of maximum production in peak hours (8:30 and 16:30). In contrast, in the case of the inclined bifacial solar cell, about 26% more in the production of electrical power was reached. These results guide similar studies in other places of the Mexican Republic and regions with similar latitudes and climate. Full article

Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mexico and Central America, found across a range of habitats from sylvatic to domestic. Vector control has relied heavily on indoor residual spraying with pyrethroids; however, reinfestation and emerging resistance have limited its long-term effectiveness. In this study, we analyzed the genetic diversity and population structure of T. dimidiata from Veracruz, Oaxaca, and Yucatan using mitochondrial markers (cyt b and ND4) and screened for knockdown resistance (kdr)-type mutations in the voltage-gated sodium channel (VGSC) gene. High haplotype diversity and regional differentiation were observed, with most genetic variation occurring between populations. The ND4 marker provided greater resolution than cyt b, revealing ten haplotypes and supporting evidence of recent population expansion. Haplotype networks showed clear geographic segregation, particularly between populations east and west of the Isthmus of Tehuantepec. The L925I mutation, highly associated with pyrethroid resistance, was detected for the first time in Mexican populations of T. dimidiata, albeit at low frequencies. These findings highlight the importance of integrating population genetic data and resistance surveillance into regionally adapted vector control strategies for Chagas disease. Full article

The Placerias quarry is a dicynodont-dominated bonebed in Upper Triassic Chinle Group strata near St. Johns in east-central Arizona, USA. Though long identified as being in strata of the lower Chinle Group, recently published numerical ages apparently indicate a stratigraphically much higher (younger) position in the Chinle section for the Placerias quarry. Nevertheless, recent analysis of outcrop and subsurface (hydrologic) data in the vicinity of the Placerias quarry confirms its stratigraphic position very low in the Chinle Group section, close to the base of the Bluewater Creek Formation. A regional Upper Triassic lithostratigraphy has been established across east-central Arizona and west-central New Mexico by nearly a century of stratigraphic studies and geologic mapping by diverse workers, and is supported by biostratigraphy; in this lithostratigraphy the Placerias quarry is near the Chinle Group base. However, U/Pb ages on zircons from Upper Triassic strata in eastern Arizona/western New Mexico have been used to reorganize this lithostratigraphy to indicate intertonguing and dramatic lithofacies changes over relatively short lateral distances. But, if the well-established lithostratigraphy is followed, the U/Pb ages are problematic, particularly where younger ages (such as at the Placerias quarry) are stratigraphically below older ages. A handful of numerical ages should not be used to over-rule well-established understanding of lithostratigraphy and biostratigraphy, unless the lithostratigraphy and biostratigraphy need to be modified based on stratigraphic data. Numerical ages need to be used judiciously and evaluated critically with regard to established lithostratigraphy, biostratigraphy and other age constraints. Full article

We performed serologic surveillance for selected arthropod-borne viruses (arboviruses) in bats and opossums in the Lacandona Rainforest, Chiapas, Mexico, in 2023–2024. Sera were collected from 94 bats of at least 15 species and 43 opossums of three species. The sera were assayed by the plaque reduction neutralization test (PRNT) for antibodies to eight orthoflaviviruses (dengue viruses 1–4, St. Louis encephalitis virus, T’Ho virus, West Nile virus, and Zika virus) and one alphavirus (chikungunya virus; CHIKV). Twelve (12.8%) bats and 15 (34.9%) opossums contained orthoflavivirus-specific antibodies. One bat (a Jamaican fruit bat) was seropositive for Zika virus, and 11 bats contained antibodies to an undetermined orthoflavivirus, as did the 15 opossums. All bats and most opossums seropositive for an undetermined orthoflavivirus had low PRNT titers, possibly because they had been infected with another (perhaps unrecognized) orthoflavivirus not included in the PRNTs. Antibodies that neutralized CHIKV were detected in three (7.0%) opossums and none of the bats. The three opossums had low CHIKV PRNT titers, and therefore, another alphavirus may have been responsible for the infections. In summary, we report serologic evidence of arbovirus infections in bats and opossums in Chiapas, Mexico. Full article

Prescribed fires are a management strategy involving the controlled application of fire to achieve specific ecological objectives. In the pine–oak forests in west-central Mexico, we conducted an experimental low-severity prescribed fire to assess its effects on hummingbird diversity. We hypothesized that low-severity prescribed fire would enhance both taxonomic and functional diversity by modifying understory vegetation structure and increasing floral resource availability. To test this, we performed point count censuses in both low-severity prescribed fire and fire-suppressed sites where wildfire had been excluded for over 40 years. Taxonomic diversity was assessed using Hill numbers to estimate true diversity across different abundance weights, while functional diversity was evaluated through indices such as functional richness, functional evenness, and functional divergence. Our results indicated that low-severity prescribed fires did not affect overall hummingbird diversity as both low-severity prescribed fire sites and fire-suppressed sites exhibited comparable species richness. However, sites with low-severity prescribed fire and concave summits showed a significantly higher abundance of common and highly abundant species. Notably, species richness did not align with functional richness, as the fire-suppressed site exhibited the highest functional diversity. These findings suggest that hummingbird community structure is influenced by a combination of fire history, topography, vegetation structure, and floral resource availability. We recommend maintaining a heterogeneous forest matrix, incorporating patches with fire suppression, and areas subjected to prescribed fires of varying severity. This multifaceted approach enhances both taxonomic and functional biodiversity, promoting habitat heterogeneity and ensuring the persistence of diverse hummingbird assemblages in fire-prone ecosystems. Full article

Since 2011, Sargassum seaweed has spread widely outside the Sargasso Sea, causing massive strandings on the coasts of the West Indies and Mexico, causing serious economic, ecological, and health problems. This Atlantic pelagic alga has the characteristic of moving in rafts. According to in situ observations, their size and shape can vary with the wind. To better understand the effect of wind on Sargassum coverage and aggregation size, we conducted a large temporal (2019–2022) and spatial scale study in the West Indies using OLCI/Sentinel-3 satellite imagery. During this period, a database of nearly 1 million Sentinel-3 aggregations, including their geometric and wind characteristics, was established. Analysis of the size distribution showed that wind has a dual effect on disaggregation and agglomeration depending on wind speed and aggregation size: (1) low winds favor agglomeration for the smallest aggregations and disaggregation for the largest aggregations; (2) high winds favor disaggregation for all aggregation sizes. In addition, topography also plays a role in size distribution: the Caribbean arc favors agglomeration over offshore zones, and coastal areas favor disaggregation over offshore zones. Full article

Gray snapper (Lutjanus griseus) move from inshore to offshore habitats as they mature and spawn along the West Florida Shelf. The connectivity between offshore spawning sites and inshore settlement regions along the Eastern Gulf of America (formerly Gulf of Mexico, hereafter Gulf) coast is unknown, and this study therefore predicted these larval dispersal pathways. To determine larval transport, an ocean model was integrated with the Connectivity Modeling System (CMS), which is a biophysical model that allowed for the inclusion of larval behavior and updated spawning information for the gray snapper. Our larval dispersal model showed that spawning sites offshore of Tampa, in the Florida Keys, and in the Florida Middle Grounds had the highest percentages of successfully settled larvae inshore. Larvae that were spawned at the offshore Tampa Bay and offshore Southwest Florida spawning sites were mostly transported to the Tampa Bay and Southwest Florida settlement regions, showing local retention. In contrast, larvae spawned offshore in the Florida Middle Grounds were transported northwest, exclusively to the Florida Panhandle. In addition, there was no difference in the proportion of successful larval settlers between full and new moon spawning events. Since gray snapper are an important recreational fishery in the eastern Gulf, especially off the west coast of Florida, it is important to identify spawning sites that have the largest proportions of settling larvae, such as offshore Tampa Bay. Full article

Background: Bees rely on plants for nutrition and reproduction, making the preservation of natural areas crucial as pollinator reservoirs. Seasonal tropical dry forests are among the richest habitats for bees, but only 27% of their original extent remains in Mexico. In contrast, temperate forests harbor fewer bee species and face high deforestation rates, with 40% of their area converted to other land uses. This study aimed to estimate the α and β diversities of wild bees and compare bee–plant interaction networks between these two vegetation types. Methods: Wild bees and their interactions with plants were monitored for one year in four sites within the Área de Protección de Flora y Fauna Sierra de Quila. Two sites corresponded to seasonal tropical dry forest and two to temperate forest. α and β diversity, connectance, nestedness, web asymmetry, and niche overlap were analyzed. Results: Sierra de Quila harbors high bee diversity, with 155 species in tropical dry forest and 103 in temperate forest. Species turnover between vegetation types was high, although nine species used floral resources in both forests, connecting the interaction networks. Conclusions: Sierra de Quila diverse habitats promote high bee diversity, with niche partitioning and low connectance facilitating coexistence across different vegetation types. Full article

Arthropods are hummingbirds’ principal source of nitrogen, fatty acids, and micronutrients. Despite the nutritional importance of arthropods for hummingbirds, our understanding of the factors influencing their consumption and their relative role as an energy source remains limited. Here, we aimed to describe the use of arthropods by a hummingbird ensemble in a seasonal temperate mountain ecosystem in West Mexico during one annual cycle. We compared arthropod capture attempt rates among six different humming species. Also, we investigated the impact of seasonal variation in food availability on the arthropod capture attempt rates of the White-eared Hummingbird (Basilinna leucotis), the sole species observed foraging for arthropods in all seasons. We found that hummingbirds ingested arthropods from different orders (Araneae, Hemiptera, Psocoptera, Hymenoptera, and Diptera), with arthropod capture attempt rates varying wildly among species. The arthropod capture attempt rates of the White-eared Hummingbird showed a significant positive correlation with arthropod availability, peaking during the warm-dry season when floral nectar was scarce and arthropod availability was high. Our data show that arthropod ingestion is crucial for some hummingbird species, mainly when nectar availability is limited or absent in the environment. Full article

The forests and grasslands in the U.S. are vulnerable to global warming and extreme weather events. Current satellites do not provide historical vegetation density images over the long term (more than 50 years), which has restricted the documentation of key ecological processes and their resultant responses over decades due to the absence of large-scale and long-term monitoring studies. We performed point-by-point regression and collected data from 391 tree-ring plots to reconstruct the annual normalized difference vegetation index (NDVI) time-series maps for the contiguous U.S. from 1850 to 2010. Among three machine learning approaches for regressions—Support Vector Machine (SVM), General Regression Neural Network (GRNN), and Random Forest (RF)—we chose GRNN regression to simulate the annual NDVI with lowest Root Mean Square Error (RMSE) and highest adjusted R2. From the Little Ice Age to the present, the NDVI increased by 6.73% across the contiguous U.S., except during some extreme events such as the Dust Bowl drought, during which the averaged NDVI decreased, particularly in New Mexico. The NDVI trend was positive in the Northern Forest, Tropical Humid Forest, Northern West Forest Mountains, Marin West Coast Forests, and Mediterranean California, while other ecoregions showed a negative trend. At the state level, Washington and Louisiana had significantly positive correlations with temperature (p < 0.05). Washington had a significantly negative correlation with precipitation (p < 0.05), whereas Oklahoma had a significantly positive correlation (p < 0.05) with precipitation. This study provides insights into the spatial distribution of paleo-vegetation and its climate drivers. This study is the first to attempt a national-scale reconstruction of the NDVI over such a long period (151 years) using tree rings and machine learning. Full article

The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (~72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated. Full article

Urbanization is one of the leading causes of habitat loss, which has increased significantly in tropical regions in recent years, leading to the loss of species, their ecological functions, and evolutionary history. To determine the effect of urbanization on the diversity of bat communities in urban and suburban environments, we analyzed the α and β taxonomic, functional, and phylogenetic diversities at four sites along urbanization gradients surrounding a rapidly expanding city (Oaxaca City) in southern Mexico. We recorded bats using conventional techniques such as mist nets and acoustic monitoring. We calculated the diversity of bats in four sites with different urbanization conditions: urban (1), suburban (1), and rural (2). To assess the degree of total differentiation and components of bat turnover and nestedness between sites, we calculated the β taxonomic, functional, and phylogenetic diversities. A total of 33 bat species were recorded. The highest taxonomic and functional diversity was observed in the Center of Oaxaca (the site with the highest level of urbanization). In contrast, the highest phylogenetic diversity was found in the West (the site with the lowest level of urbanization). The total β taxonomic diversity was higher than the functional and phylogenetic diversity. Regarding the contributions of turnover and nestedness, turnover made a more significant contribution than nestedness to the taxonomic and phylogenetic β diversity. In contrast, functional nestedness contributed more to the functional β diversity than turnover. Tadarida brasiliensis, Desmodus rotundus, Sturnira hondurensis, and S. parvidens were recorded in all three urbanization conditions. In the most urbanized site, four Myotis species were recorded: M. fortidens, M. keaysi, M. thysanodes, and M. velifer. We suggest that the analysis of different dimensions of diversity is essential and should be considered to strengthen conservation strategies; moreover, we suggest the preservation of native vegetation mosaics and water bodies within the city to maintain bat diversity. Full article

The agouti (Dasyprocta leporina) is a promising protein source in the Caribbean, Mexico, and South America. This study assessed the impact of three by-product diet formulations on intensively reared agoutis, including a cost analysis and nutritional evaluation as well as the nutritional composition, digestibility, and economic viability of three experimental diets. Sixteen adult male agoutis were individually housed at the University of the West Indies’ Field Station. After a two-week acclimatization, a four-week data collection phase followed. The four treatments included a control diet of commercial rabbit pellets and three experimental diets with varying by-product ratios. Key findings revealed that Treatment 2 had elevated Dry Matter, Crude Fat, and fiber but potentially compromised digestibility due to higher fiber and lignin. Treatment 1 resulted in the highest morbidity and was discontinued after two weeks due to significant weight loss but demonstrated the most cost-effective results, with the lowest variable cost per 45 kg, the lowest feeding cost to reach 3 kg, and the highest gross margin. Treatment 2 effectively maintained animal weight. Treatment 3 showed promising growth due to low levels of Neutral Detergent Fiber (NDF) and Acid Detergent Lignin (ADL). Alternative dietary feedstuffs from agricultural by-products show potential for sustaining body weight in adult male agoutis, but further research is needed to refine nutritional requirements for growing agoutis. Full article

Reptiles are threatened by anthropogenic landscape transformation, largely due to agriculture. However, ecosystems nowadays constitute a matrix of fragmented landscapes. We analyzed a heterogeneous landscape’s reptile taxonomic and functional diversity patterns across ten land cover/use types in Jalisco state, in west-central Mexico. At the alpha diversity level, we assessed the taxonomic diversity using q-order indices, and functional diversity with multidimensional indices (FRic, FDiv, and FEve) by land cover/use. We evaluated the differences in species composition among land cover/use types (beta diversity). We utilized multidimensional distance-based analyses (dbRDA) to evaluate the association between reptile diversity, habitat structure, and environmental variables. Species richness did not correlate with functional richness across land cover types overall, except for riparian habitat surrounded by crops (RH-C), which exhibited higher species richness and functional diversity. Secondary vegetation surrounded by temperate forest (SV-TF), riparian habitat surrounded by tropical dry forest (RH-TDF), and RH-C were the land cover/use types with the most functional groups. Herbaceous cover is crucial for preserving both reptile diversity facets in this landscape. These findings suggest that the availability of resources (e.g., riparian habitat and herbaceous cover) regardless of perturbation level could be more relevant for reptile diversity than the condition (tropical vs. temperate) due to the high plasticity and adaptation of the group. It is essential to recognize the ecological value of these habitats by adopting a holistic approach that values the intrinsic and ecological importance of reptile diversity. Full article

Blooms of the harmful dinoflagellate Karenia brevis on the West Florida Shelf (WFS), Gulf of Mexico, are hypothesized to initiate in association with the colonial cyanobacterium Trichodesmium spp. and benefit from dissolved organic nitrogen (DON) release derived from N₂-fixation by the cyanobacteria. Previous studies have detected DON release using direct experimental measurements, but there have been few studies that have followed nutrient release by in situ blooms of Trichodesmium and the associated plankton community. It was determined that long-term Trichodesmium spp. and Karenia brevis abundances on the WFS were related, following a 2-month lag. A separate Eulerian study of a Trichodesmium erythraeum bloom event was conducted over 9 days on the Great Barrier Reef. Concentrations of T. erythraeum increased over the course of the study, with coincident increases in dinoflagellate abundance and decreases in diatom abundance. Inside the bloom, concentrations of NH₄⁺, PO₄³⁻, and DON increased significantly. The copepod grazer Macrosetella gracilis also increased in abundance as T. erythraeum numbers increased, contributing to nutrient release. Copepod grazing rates were measured, and N release rates estimated. Together, these studies show that Trichodesmium blooms have consequences for dinoflagellate abundance at both seasonal and ephemeral scales via direct and indirect N release. Full article