Central-western Mexico Research Articles

The bacterial assemblage in the plumage of the Violet-crowned Hummingbird (Ramosomyia violiceps) varies with contrasting environments in Central-Western Mexico

The bacterial assemblage in the plumage of the Violet-crowned Hummingbird (Ramosomyia violiceps) varies with contrasting environments in Central-Western Mexico

Holocene palaeoecological changes in a transitional climate zone of western-central Mexico: The pollen and non-pollen palynomorphs record

The Alberca de Tacámbaro (AT) is located at a transitional zone between tropical and temperate climates at the core of the North American Monsoon area. This location features a mosaic vegetation comprising pine-oak forests and tropical dry forests. Currently there is no information regarding the dynamics or evolution during the Holocene of these vegetation types. The palynological record of the last 9400 years BP preserved in the lacustrine sequence of the AT was used to document changes in the composition of terrestrial and aquatic communities, evenness, and rate of change. Pinus and Quercus forests dominated the terrestrial palynological record, but mesophytic forests were also recorded throughout the sequence. Four tropical dry forest taxa assemblage expansions were identified at 9200 to 8420 yr BP; 5900 to 5230 yr BP; 3100 to 2800 yr BP; and 2300 to 2000 yr BP. These phases correlated with times of reduced North American Monsoon intensity, suggesting that these communities thrived during drought periods. Variations in non-pollen palynomorphs were synchronic with the lithostratigraphic, geochemical data as well as with the terrestrial changes. During the Meghalayan, compositional shifts in the vegetation and increases in the herbaceous elements indicated human impact, while aquatic taxa, suggested eutrophic and warmer conditions in the lake. By examining the history of this vegetation mosaic, the data on temporal vegetation dynamics during the Holocene offered clues about the response to ongoing global warming and how climate change will likely shape plant communities in western-central Mexico.

Knowledge Management and Human Resource Management to Innovate: An Empirical Analysis in the Textile Industry

This research aims to understand the impact of knowledge management and human resource management on innovation in textile industry companies in central-western Mexico. This is a qualitative, descriptive, correlational study with a non-experimental, cross-sectional design. The sample is simply random and is made up of 386 companies in the textile industry. A structured questionnaire was applied using a Likert-type scale with five ranges. The information analysis used the Structural Equation Model (SEMPLS). In the results, the analysis of the statistical parameters t – t-student and p-value confirm the statistical significance of the Path coefficients with 95% confidence. The results of the research coincide with some of the literature. This research fills a gap in the literature on the phenomenon studied.

CO<sub>2</sub> hypogene speleogenesis in an endogenic travertine system, Mesa del Oro, New Mexico, USA

The Mesa del Oro travertine, deposited by upwelling CO2-rich spring waters, is a large and thick mantle of calcite overlying soft Triassic Chinle Formation mudstones in western central New Mexico, USA. The travertine contains a system of small caves known as the Pronoun Cave Complex. Whut Cave is the largest known cave in the complex. While the travertine hydrologic system is no longer active, there is ample evidence that Whut Cave was formed by hypogene speleogenesis. The Whut Cave entrance is a small roughly circular shaft that descends ~four meters and intersects a linear fissure-controlled passage. Mn-oxide was once mined below the entrance, leaving a five-meter-deep pit that represents the path of upwelling waters that were likely charged with CO2 and supersaturated with CaCO3 once reaching the surface. The roomiest part of the cave is immediately adjacent to the entrance, defining where most of the upwelling of groundwater and gases took place. Gypsum and other sulfates were only noted microscopically. A sample of travertine at the surface near the entrance yielded a uranium-series age beyond the limit of the method and a δ234U age of 735 ± 109 ka BP (before present). A piece of breccia vein in the mine dump associated with the Mn-oxide ore, and a rill of a drape-like crust on the cave wall, both interpreted to be products of hypogene speleogenesis and representing the oldest speleogenetic material, yielded δ234U ages of 848 ± 110 and 723 ± 109 ka BP. Altogether, materials interpreted to be speleogenetic yielded ages of ~900 – 300 ka BP. Although the cave is dry and hydrologically inactive today, cave development by CO2 hypogene speleogenesis was coeval with endogenic travertine deposition and nearby volcanism. Our interpretation suggests that all these events are linked.

The 2020 and 2021 Seismic Swarms in the Tancítaro-Paricutín Area (Uruapan- Michoacán, México) Evidence Magma Intrusion in an Area with High Density of Monogenetic Cones

The Michoacán-Guanajuato Volcanic Field (MGVF) in central-western Mexico, with more than 1,000 monogenetic volcanoes, has been well known since 1943 when an eruption formed the Paricutín volcano, 11 km to the NW of the summit of Tancítaro stratovolcano. In the highly fractured zone around Tancítaro, referred to as the Paricutín-Tancítaro region (PTR), two major seismic swarms have been recorded, the first between January 5 and February 22, 2020, and the second between May 30 and July 22, 2021. The Mexican National Seismological Service (SSN) reported a total of 4,956 earthquakes with coda magnitudes between 2.6 and 4.2. With the aim to determine the causes of the swarms and the potential hazard they may pose on the region, we first analyze their spatial distributions by relocating all of the events using the Double Difference method and testing different 1-D velocity models to select the one with the lowest residual errors. Secondly, we analyze the temporal distributions finding that their temporal occurrence fits a Mogi’s type 3 volcanic seismic swarm. We conclude that each swarm is due to stresses induced by dike-fed intrusions of moderate volumes of magma in a pre-existing temporal magma reservoir, probably a sill.

Quarrying volcanic landscapes: territory and strategies of metate production in Turícuaro (Michoacan)

In the Michoacán region of central-western Mexico, the village of Turícuaro has for centuries been a center for metate production based on andesites exploited on the slopes of Hoya Urutzen and 'El Metate' volcanoes. Surveys have been conducted in this volcanic landscape, with the invaluable help of one of the last metateros (craftsmen) family of the village, the Vidalès, in order to reconstruct the strategies adopted through time to extract this andesite over a large territory. It has been possible to propose a first mapping as well as a relative dating of the various quarrying areas. Different types of exploitations have been described, from ancient quarries, associated with archaeological occupations, to current extraction sites. The morphology of the outcrops (walls, isolated blocks) partly conditioned the organization of the quarries (flat, organized on terraces, etc). It has also been possible to observe the different strategies and organization of work associated with this activity, through the observation of the abandoned blocks, waste and roughouts. Finally, this work offers a new perspective on Mesoamerican metate quarrying strategies.

Functional Connectivity of the California Bulrush (Schoenoplectus californicus) in Central-Western Wetlands in Mexico

Wetlands are natural links between terrestrial and aquatic ecosystems maintaining biodiversity at regional and landscape levels. Wetland conservation in Mexico could benefit from understanding functional connectivity for aquatic plants. This is an ongoing research project aimed at identifying the landscape factors that determine gene flow and genetic diversity of Schoenoplectus californicus in the highland wetlands of Central-Western Mexico. Between 10 to 30 leaf tissue samples from S. californicus individuals were collected in natural and artificial wetlands in the states of Michoacán, Guanajuato, and Jalisco for genomic DNA extraction. A total of sixteen nuclear microsatellite markers developed for S. americanus will be transferred and genotyped to estimate genetic diversity and differentiation and to statistically test their relationship with landscape elements. To date, 419 individuals from 27 sites have been sampled from 11 wetlands. Six out of 16 microsatellites have been transferred. The results of this work will guide the design of wetland management and conservation strategies at the landscape scale, particularly in anthropogenic landscapes where wetlands are at high risk.

Holocene climate variability and the effect of anthropogenic activities on the vegetation landscape of western-central Mexico

Atmospheric forcings control climate variability and at the same time control vegetation distribution and forest fires during the Holocene. Paleoenvironmental studies are scarce in western Mexico, particularly those documenting vegetation change, landscape dynamics, and fire regimes. This study presents a vegetation and fire occurrence reconstruction in the Etzatlán-Magdalena paleolake, western Mexico, during the Holocene. The reconstruction relies on fossil pollen, macrocharcoal and microcharcoal analyses of a clay sediment core. In the early Holocene (10–5.8 ka), climatic conditions were humid between 10 and 9 ka, represented by cloud forest of Liquidambar, Juglans, and Betulaceae. After 9 ka Quercus forest expanded and a trend towards warm conditions was detected, associated with high fire activity, suggesting the presence of a dry forest. Fire episodes at local and regional scale had a long-term negative effect on temperate and cloud forests. In the middle Holocene (5.8–2.1 ka), temperate forest was replaced by dry forest, indicating a drier climate. In the late Holocene (2.1–0.3 ka), the expansion of disturbance taxa and the low local fires indicated an open landscape and dry conditions. Human activity was documented by an increase of Cheno-Amaranthaceae, Poaceae and microcharcoal concentration after 3.5 ka. This research provides relevant information on the vegetation dynamics in a region with a long history of human settlement.

Evaluation of Forestry Component Survival in Plots of the Program “Sembrando Vida” (Sowing Life) Using Drones

Reforestation is one of the main actions undertaken to mitigate the effects of climate change. In Mexico, the Federal Government program “Sembrando Vida” (Sowing Life) is currently the most important reforestation effort. It aims to recoup forest cover and achieve food self-sufficiency through the establishment of agroforestry systems. The evaluation of tree survival in reforested areas helps to identify achievements and failures, as well as aspects of the program that require improvement. However, given the magnitude of this program, evaluation using traditional methodologies is labor-intensive and costly. In this context, drones equipped with high-resolution cameras are a promising tool. The objective of this study was to evaluate the feasibility of using drones to monitor tree survival in reforested areas. This study was conducted in 12 randomly chosen plots, benefited by the “Sembrando Vida” program, located on the Purépecha Plateau in the state of Michoacán, in central–western Mexico. Field surveys with GPS were conducted to record the total number of live and dead forest-tree seedlings. Simultaneously, high-resolution images were captured using a DJI Phantom 4 Pro drone equipped with an RGB camera for subsequent visual interpretation in a geographic information system to determine the status of each seedling and calculate the rates of survival. ANOVA was performed to compare the survival calculated using the drone images compared to that recorded in the field. No significant difference was found between survival estimated using the drone and that recorded directly in the field in any of the study plots, although the drone overestimated survival by an average of 6%, mostly due to the presence of dead seedlings that had already lost their foliage and were thus missed when scoring the RGB image. It is therefore concluded that the estimation of survival using drones is a reliable method. For future research, it is recommended to evaluate machine-learning algorithms in terms of detecting both living and dead trees in reforested sites. It is also recommended to use multispectral thermal cameras and LiDAR technology to broaden the knowledge of the different levels of vigor/stress present in the vegetation.

Notes on Bat Falcon (<i>Falco rufigularis</i>) distribution, nesting, and diet in central-western Mexico

The Bat Falcon may nest in constructions in urban areas. It feeds on bats, birds, and insects. We present records on its distribution, nesting, and diet in western central Mexico. We observed a Bat Falcon couple breeding in 2013 and 2015 in a wall’s cavities from a town’s construction. We collected the remains of the prey consumed by the juveniles in the nest cavities after the juveniles abandoned them in 2013 and 2015, and additionally the remains of prey under the parent’s perches next to the nest cavity in 2015. The nesting period was from March to at least the middle of June. Some of the dietary items during the nesting period were one rodent, four bats, six birds, grasshoppers, and beetles. This study confirms that the Bat Falcon breeds in urban areas and preys upon local species.

Using species distribution modeling to generate relative abundance information in socio-politically unstable territories: Conservation of Felidae in the central-western region of Mexico.

The distribution range and population abundance of species provide fundamental information on the species-habitat relationship required for management and conservation. Abundance inherently provides more information about the ecology of species than do occurrence data. However, information on abundance is scarce for most species, mainly at large spatial scales. The objective of this work was, therefore, to provide information regarding the population status of six wild felids inhabiting territories in Mexico that are inaccessible or politically unstable. This was done using species distribution models derived from occurrence data. We used distribution data at a continental scale for the wild felids inhabiting Mexico: jaguar (Panthera onca), bobcat (Lynx rufus), ocelot (Leopardus pardalis), cougar (Puma concolor), margay (Leopardus wiedii), and jaguarundi (Herpailurus yagouaroundi) to predict environmental suitability (estimated by both Maxent and the distance to niche centroid, DNC). Suitability was then examined by relating to a capture rate-based index, in a well-monitored area in central western Mexico in order to assess their performance as proxies of relative abundance. Our results indicate that the environmental suitability patterns predicted by both algorithms were comparable. However, the strength of the relationship between the suitability and relative abundance of local populations differed across species and between algorithms, with the bobcat and DNC, respectively, having the best fit, although the relationship was not consistent in all the models. This paper presents the potential of implementing species distribution models in order to predict the relative abundance of wild felids in Mexico and offers guidance for the proper interpretation of the relationship between suitability and population abundance. The results obtained provide a robust information base on which to outline specific conservation actions and on which to examine the potential status of endangered species inhabiting remote or politically unstable territories in which on-field monitoring programs are not feasible.

Population structure and reproduction of the hairy fruit-eating bat, Artibeus hirsutus, in central-western Mexico

The hairy fruit-eating bat Artibeus hirsutus is endemic to Mexico and is considered a rare species. The little biological and ecological data on this species does not provide much information on its conservation status. The objective of this work was to evaluate the population structure and reproductive activity of a colony of A. hirsutus in west-central Mexico. We visited 12 times Isla Grande Atoyac, Jalisco. The individuals were captured inside the 2 caves with bucket traps or by hand directly from the cave roof, and with mist nets placed within the vegetation. We marked 77 individuals (67 adults, 5 juveniles, and 5 newborns), of which 34 were recaptured. The pooled recapture rate was 58.47%, and it increased from March to October and decreased in November and December. The minimum-number-alive value was higher in February (34) and lower in October (5), with an average of 21.1 individuals. Among the adult bats, 25.3% were males and 74.6% were females, with an overall female-biased sex ratio of 1:3.2. Sexual dimorphism was observed, with a significantly greater forearm length in females (55.7 mm) than males (54.4 mm). The study population showed a seasonal bimodal polyestry reproductive pattern.

The relationship between the fishermen and the American crocodile (Crocodylus acutus) in the Mexican central western Pacific: a narrative analysis

Objective: To analyze the relationship between the fishermen of central western Mexico and the river crocodiles (Crocodylus acutus), emphasizing the resulting conflict. Design/Methodology/Approach: The work was carried out with 22 fishermen from the Cuyutlán and Alcuzahue lagoons in Colima, Mexico. Four participative workshops were organized per community, in order to explore the positive and negative aspects of the relationship, the perception and knowledge about the ecosystem functions of the crocodile, and the management practices and actions associated with this relationship, as well as to determine the natural participants and factors that influence the said relationship. The workshops were recorded and the resulting data was subjected to a narrative analysis and a summary. Results: Harmonious relationships are recorded, including the creation of bonds between humans and crocodiles and recognizing the benefits to fishing and the ecosystem function of the crocodile. The conflictive relationships identified were related to fishing, the reduction of fishing resources, and accidents. The strategies used to prevent conflicts are related to the dangerous zones, the behavior of the crocodiles, and the killing of the animals to reduce their presence. Additionally, compensation schemes, a collective management of fishing resources, and the replacement of fishing by the exploitation and capture of the crocodile were taken into consideration. Study Limitations: Besides the fishermen’s, the point of view of other participants should be determined. Conclusions: The relationship between fishermen and crocodiles is both harmonious and conflictive. On the one hand, both receive benefits; on the other hand, fishermen suffer economic, operative, and life style impacts, which create inauspicious scenarios for the conservation of the reptile.

Holocene Climate Variability Over the Vegetation Landscape in Western-Central Mexico and Evaluation of Anthropogenic Activities

Holocene Climate Variability Over the Vegetation Landscape in Western-Central Mexico and Evaluation of Anthropogenic Activities

Prevalence and risk factors of Neospora caninum and Toxoplasma gondii infection in breeding ewes from central western Mexico.

The objective of the study was to analyse the prevalence of infection by N. caninum and T. gondii in breeding ewes from central western Mexico. For this purpose, 184 blood samples were collected from sheep in the reproductive stage, which were analysed by ELISA and PCR tests, respectively, and the association between seroprevalence and some management factors was estimated by means of a logistic regression analysis. For N. caninum, a seroprevalence of 15.22% was identified, while the DNA detection in blood was 14.13% (26/184); positive animals were found in 75% of the farms (6/8). The variables poor placental waste management (OR 8.4), abortion history (OR 1.5) and presence of rodents (OR 1.3) were identified as risk factors for N. caninum infection. In the case of T. gondii, a seroprevalence of 61.96% was found, and antibodies were detected in eight farms included in the study; no positive samples were identified for T. gondii by the PCR test. The main identified risk factors for T. gondii were as follows: poor hygiene conditions (OR 12.5), presence of cats (OR 9.5), presence of other domestic animals (OR 5.7), urban context of the farm (OR 9.5) and public water supply (OR 5.3). The seroprevalence of co-infection of T. gondii and N. caninum in breeding ewes was 7% (13/184; 95% CI 6.92-7.20). T. gondii has a high seroprevalence while N. caninum was of lower proportion, and both may be associated with reproductive losses for these herds studied.

Volcanism and Curie Isotherm Distribution in the Jalisco Block, Mexico

A suitable combination of magnetic field determinations is assembled in the whole area of the Jalisco block in central-western Mexico; it serves as the basis for calculations of the Curie Point Isotherm by means of Spectral Analysis. The Jalisco block contains numerous volcanic manifestations; an attempt is made at correlating the Curie Isotherm (CI) with volcanic manifestations and its implicit risk to nearby populated regions. A preliminary analysis of this isotherm is carried out using areas of 60 × 60 km2, where the volcanic regions at the NW and SE portions of the Tepic-Zacoalco (T-Z) rift coincide with shallow layers of the CI. Results show an unexpected region in the middle of the T-Z rift, where the isotherm deepens to 12 km depth and volcanism appears to be missing. The authors argue that this phenomenon may be associated with a flare up episode occurring at 5-3 Ma along the rift. Varying the area used for the calculation of the CI, from 30 × 30 km2 to 120 × 120 km2, illustrates how the concomitant changes in volume affect the depth of penetration. The authors find exceptional regions in which the CI shows shallow depths at all area sizes used in the calculations; this consistency is interpreted as a magnetic alteration of the crust originating at mid-crustal depths. These regions also correspond to high values of the Bouguer anomaly reported elsewhere. Six magneto-stratigraphic profiles are presented for the results of the 60 × 60 km2 calculations, where geologic, topographic, and magnetic properties are displayed along their length.

Notes on Mexican Woodnymph (Eupherusa ridgwayi) Behavior and Nesting in Central-western Mexico

The Mexican Woodnymph (Eupherusa ridgwayi) is endemic to west-central Mexico with a narrow distribution range and relatively small population size. The species nest, nesting activities and nestling's characteristics were unknown until now. We generated a map of this species using data from BirdLife International, the Global Biodiversity Information Fund database, e-Bird, and the Naturalista. We used the Mexican Woodnymph records in Jalisco and projected them on a vegetation map. We documented a female constructing a nest, later nesting, until the nestlings flew out of the nest in the cloud forest in central-western Mexico: Jalisco state. The nest site was characterized and the materials used for the nest construction were determined. In addition, we documented several observations made on territorial and foraging behavior.

Epizootics of entomopathogenic fungi at overwintering sites of Oebalus mexicana Sailer (Hemiptera: Pentatomidae) from Western Mexico

BackgroundOebalus mexicana Sailer (Hemiptera: Pentatomidae) is an important pest of sorghum in Central-Western Mexico. In addition to damaging the grain, it is a vector of the panicle blight, Fusarium moniliforme. Oebalus mexicana hibernates at > 2200 m above sea level (masl), and its control in these sites is through entomopathogenic fungi (EPF). Their effectiveness could be misperceived as natural epizootics at hibernation sites. To characterize fungal epizootics associated with hibernating adults of O. mexicana, during 2019 and part of 2020, a study was established in the Zináparo hill, Michoacan, Mexico. Three sampling strata were defined—two at low (2219 masl) and high levels of elevation (2351 masl), and another one at intermediate elevation (2244 masl) and soil humidity most of the year. Under the leaf litter, live arthropods and corpses with and without mycosis were recorded every 2 weeks; associated EPF were isolated and identified. Soil humidity, temperature, and RH under the litter were recorded.ResultsSix genera of fungi were identified, with Beauveria being the most prevalent. Mortality of O. mexicana in the field was > 80%, with a high correlation (r = 0.85–0.97) with mortality due to fungi (> 65%). The humidity of soil and litter created a suitable environment for the development of epizootics. The highest prevalence was registered at the elevations of 2244, 2351, and 2219 masl, respectively. More than 15 families of arthropods were registered, several of them with the presence of mycosis. Their permanence as alternate hosts contributed to the persistence of the fungi. Field and laboratory evidences suggested that the frequent flights of O. mexicana favoured the self-dissemination of EPF. Thus, more than 37% of live individuals with inoculum and subsequent infection and death were recorded.ConclusionsThe EPF disease at overwintering sites of O. mexicana was enzootic, and under favourable conditions it can become epizootic. The high levels of natural control in hibernation sites suggest that additional control measures for O. mexicana are unnecessary; on the contrary, the conservation of these sites as reservoirs of EPF is proposed for a sustainable use in the management of this and other pests.

Weeds Harbor Fusarium Species that Cause Malformation Disease of Economically Important Trees in Western Mexico.

Mango malformation disease (MMD) caused by Fusarium spp. is an important limiting factor in most production areas worldwide. Fusarium mexicanum and F. pseudocircinatum have been reported as causing MMD in Mexico. These two pathogens also cause a similar disease in Swietenia macrophylla (big-leaf mahogany malformation disease) in central western Mexico, and F. pseudocircinatum was recently reported as causing malformation disease in Tabebuia rosea (rosy trumpet) in the same region. These studies suggest that additional plant species, including weeds, might be hosts of these pathogens. The role that weed hosts might have in the disease cycle is unknown. The objectives of this work were to recover Fusarium isolates from understory vegetation in mango orchards with MMD, identify the Fusarium isolates through DNA sequence data, and determine whether F. mexicanum is capable of inducing disease in the weedy legume Senna uniflora (oneleaf senna). Additional objectives in this work were to compare Fusarium isolates recovered from weeds and mango trees in the same orchards by characterizing their phylogenetic relationships, assessing invitro production of mycotoxins, and identifying their mating type idiomorph. A total of 59 Fusarium isolates from five species complexes were recovered from apical and lateral buds from four weed species. Two of the species within the F. fujikuroi species complex are known to cause MMD in Mexico. Trichothecene production was detected in five isolates, including F. sulawense and F. irregulare in the F. incarnatum-equiseti species complex and F. boothii in the F. sambucinum species complex. Both mating types were present among mango and weed isolates. This is the first report of herbaceous hosts harboring Fusarium species that cause mango malformation in Mexico. The information provided should prove valuable for further study of the epidemiological role of weeds in MMD and help manage the disease.

Victory on Earth or in Heaven: Mexico's Religionero Rebellion

Victory on Earth or in Heaven: Mexico's Religionero Rebellion