Mexican Localities Research Articles

Systematics and paleobiology of new bison occurrences from the Late Pleistocene of central Mexico

This study presents new findings of bison remains associated with alluvial plains in central Mexico dating back to the Late Pleistocene. These discoveries encompass eight sites in Hidalgo (Conejos, Ventoquipa, Barranca del Berrendo, Barranca Jagüey Viejo, Las Cajas, El Barrio, Monte Alegre, and San Gabriel Azteca) and two sites in Puebla (Barranca Policarpio and Barranca Xocoa). Biometrical analysis was conducted on the herein studied material, consisting of a horn core fragment, a skull fragment, two mandible fragments, five isolated teeth, and several postcranial remains. A comparative study with selected specimens indicates the presence of Bison antiquus and B. cf. latifrons. The record represents the first reported occurrences of these species for the states of Hidalgo and Puebla respectively. Furthermore, the analysis of carbon (δ13C) and oxygen (δ18O) isotopes in tooth enamel apatite from the material of Hidalgo and Puebla was used to characterize the bison's diet and habitat, providing evidence of the flexible dietary regime observed in Pleistocene bison populations and that were common inhabitants of mixed environments. Body mass estimation of some individuals (average weight ≈ 450 kg) is in the lower limit of B. antiquus populations from the Late Pleistocene of North America. New knowledge about the geographical presence of Bison antiquus and B. cf. latifrons in central Mexico is provided. Comparison with another bison record of these species from North America suggests a biochronological delay between them, representing a younger time interval for Bison antiquus (maximum age at 50 ka), allowing us to biostratigraphically constrain some Mexican localities containing bison remains.

Diversity of an Odonata assemblage from a tropical dry forest in San Buenaventura, Jalisco, Mexico (Insecta, Odonata).

The patterns of richness, diversity, and abundance of an odonate assemblage from San Buenaventura, Jalisco are presented here. A total of 1087 specimens from seven families, 35 genera and 66 species were obtained through monthly samplings of five days each during a period of one year. Libellulidae was the most diverse family (28 species), followed by Coenagrionidae (21), Gomphidae (7), Aeshnidae (6), Calopterygidae (2), Lestidae (1) and Platystictidae (1). Argia was the most speciose genus. The highest species richness and Shannon diversity were found during August and September, whereas the highest abundance was observed in June and the highest Simpson diversity was recorded in September - all of which were associated with the rainy season. The highest values of phylogenetic diversity were found from June to October. The different diversity facets of this assemblage were positively correlated with precipitation and minimum temperature, whereas maximum temperature showed no influence. In addition, we found that this odonate diversity was higher than most Mexican localities with tropical dry forest (TDF) studied. We continue our efforts to describe the patterns of richness, diversity and abundance of some insect groups associated with the tropical dry forest ecosystem in Mexico, following a latitudinal gradient of the distribution of this ecosystem in the country. Our emphasis here was to evaluate the spatial and temporal patterns of richness and diversity of an Odonata assemblage from Jalisco, Mexico.

Entomopathogenic fungi (Ascomycota: Hypocreales) on a termite (Blattodea: Mastotermitidae) trapped in Miocene amber from Chiapas, Mexico

ABSTRACT Palaeomycological material has rarely been reported in Mexican localities, especially parasitic fungi. In this paper, we present the first formal report of an interaction between an entomopathogenic fungus and an insect trapped in the Miocene amber from Chiapas, Mexico. The described syninclusion corresponds to two well-developed fungal fruiting bodies and a third one in development, assigned to the order Hypocreales (Ascomycota: Sordariomycetes), emerging from the thorax and abdomen of a termite (Blattodea: Mastotermitidae). This syninclusion represents a remarkable example of biological interactions in ancient tropical environments reflected in the fossil record.

Virulence and Reproduction of Entomopathogenic Nematodes Isolated from a Single Mexican Locality

Abstract Entomopathogenic nematodes (EPNs) are important biological control agents of insect pests. Strains or isolates obtained in specific regions and utilized in situ might contribute to the success of EPNs, since they are adapted to local abiotic conditions. We isolated and identified three isolates each of Heterorhabditis bacteriophora Poinar and Steinernema carpocapsae (Weiser) from soils at Saltillo, Coahuila State, Mexico. These six isolates were bioassayed against larvae of Tenebrio molitor L., using six concentrations of infective juveniles (IJs) per larva (0, 10, 25, 50, 100, 200). EPN-induced mortality of the isolates ranged from 15.2% to 100%. The designated M5 isolate of S. carpocapsae caused 100% mortality after 72 h at concentrations ≥25 IJs/larva with a median lethal concentration of 4.99 IJs/larva. Comparison of mortality levels induced at the same concentration of the six EPN isolates indicated that the Steinernema isolates, in general, induced higher mortality levels than the Heterorhabditis isolates. IJ production in T. molitor larvae also was greatest with the M5 isolate of S. carpocapsae following exposure of larvae to a concentration of 100 IJs/larva with a mean of 17,320 IJs/larva. Based on induced mortality and IJ production, the S. carpocapsae M5 isolate appears to be a viable candidate for further study and possible development for use in insect pest management programs. This study indicates that naturally coexisting local nematode isolates possess different attributes critical for their use as biocontrol agents.

House Condition Scoring Scale as a Risk Indicator of Infestation by Aedes in Two Mexican Localities.

Mexico has shown an increase in dengue incidence rates. There are factors related to the location that determine housing infestation by Aedes. This study aimed to determine factors associated with housing infestation by immature forms of Aedes spp. in the dengue endemic localities of Axochiapan and Tepalcingo, Mexico, from 2014 to 2016. A cohort study was carried out. Surveys and inspections of front- and backyards were conducted every 6 months, looking for immature forms of Aedes spp. A house condition scoring scale was developed using three variables (house maintenance, tidiness of the front- and backyards, and shading of the front- and backyards). Multiple and multilevel regression logistic analysis were conducted considering the housing infestation as the outcome and the household characteristics observed 6 months before the outcome as factors; this was adjusted by time (seasonal and cyclical variations of the vector). The infestation oscillated between 5.8% of the houses in the second semester of 2015 and 29.3% in the second semester of 2016. The factors directly associated with housing infestation by Aedes were the house condition score (adjusted odds ratio [aOR]: 1.64; 95% CI: 1.40-1.91) and the previous record of housing infestation (aOR: 2.99; 95% CI: 2.00-4.48). Moreover, the breeding-site elimination done by house residents reduced the housing infestation odds by 81% (95% CI: 25-95%). These factors were independent of the seasonal and cyclical variations of the vector. In conclusion, our findings could help to focalize antivectorial interventions in dengue-endemic regions with similar demographic and socioeconomic characteristics.

Chemical Profile and Antioxidant Activity of Essential Oils and Polyphenolic Compounds of Lippia Graveolens from Different Mexican Localities

Extraction of polyphenolic fraction and essential oils (EOs) from Lippia graveolens (Mexican oregano) leaves were explored using innovative and conventional extraction techniques such as ultrasound assisted extraction (UAE) and steam distillation, respectively. The metabolites were further analyzed to evaluate their bioactivity as antioxidants and the identification of the chemical profile was performed using a UPLC-ESI-Q/TOF-MS2 and GC-MS. The antioxidant assays on EOs showed potential as inhibitors of lipid oxidation, and the polyphenolic fraction obtained higher inhibition activity against DPPH• radical. The lower IC50 for DPPH• radical corresponded to the phenolics from “San Pedro” with 545.40 ± 47.2 μg mL-1, and the higher inhibition of lipid oxidation appertained to EOs (99.06 ± 3.91%). Furthermore, the GC-MS tentative characterization identified sixty-one compounds for EOs, and UPLC-ESI-Q/TOF-MS2 showed six identified compounds, the tentative compounds englobe flavonoids, terpenes, sesquiterpenes xanthines, and dicarboxylic acid. The present study demonstrated that Mexican crops of L. graveolens possess essential oils and polyphenolic fractions with strong antioxidant activity, which might be useful in the food and pharmaceutical industries.

The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions

The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing between atmospheric and MORB-like fluids (e.g.,40Ar/36Ar < 1,200). DVF and SQVF nodules record low40Ar/36Ar and4He/20Ne that confirm the existence of recycled atmospheric-derived noble gases in the local mantle. The averages of the Rc/Ra ratios (3He/4He corrected for atmospheric contamination) measured in Mexican localities are within the MORB-like range: DVF= 8.39 ± 0.24 Ra, SQVF = 7.43 ± 0.19 Ra and SCN lavas = 7.15 ± 0.33 Ra (1σ). With the aim of assessing the isotopic variability of the Mexican lithospheric mantle, the above results were compared with similar data previously obtained from ultramafic nodules found in the Ventura Espiritu Santo Volcanic Field (VESVF), another Quaternary monogenetic volcanic complex belonging the Basin and Range. The higher3He/4He ratios in DVF relative to those reported for the VESVF and the SQVF are explained as reflecting different ages of mantle refertilization, triggered by the retreating of the Farallon slab (∼40 Ma ago) and associated delamination slab processes. We propose that the DVF mantle was refertilized more recently (<10 Ma ago) than the mantle beneath the SQVF and VESVF (∼40–20 Ma ago). On the other hand, He-Ne-Ar compositions of SCN olivines share similarities with VESVF xenoliths, suggesting a relatively homogeneous lithospheric mantle in central Mexico. Finally, DVF and the SCN samples exhibit δ13C values within the MORB range (comparable to other values previously reported in fluid inclusions and fumaroles from Popocatépetl, Colima—Ceboruco volcanoes). While we explain the MORB-like carbon signatures of the DVF samples as the result of the above-mentioned refertilization process, the SCN signatures likely reflect either (i) trapping of isotopically fractionated CO2derived from magmatic degassing or (ii) a mantle source unaffected by subduction-related crustal carbon recycling.

Collembola (Hexapoda) of Malaise traps from two localities in Tlaxcala, Mexico

Springtails (Collembola) from two temperate forest sites, “Ejido Los Búfalos” (LB) and “Bosque Mágico de Piedra Canteada, Santuario de la Luciérnaga” (PC), in Tlaxcala state, central Mexico, were sampled monthly with Malaise traps. More than 38,000 specimens from 10 species were collected and studied. Although abundance values between both study sites were highly different, no significant effect of locality and sampling date was found according to a two-way ANOVA unbalanced test because of the high variance between recorded data. Shannon’s diversity index for LB was H’=0.61 and for PC was H’=1.08, with a significant difference in diversity between both sites. Most abundant springtails were Entomobryidae: Seira sp. (n=21,091 individuals in LB and n=6,424 in PC), Americabrya arida (6,214 and 2,860), and Willowsia mexicana (19 and 852); few Neanuridae: Pseudachorutes (241 and 169); Isotomidae: Isotoma (2 and 3); Katiannidae: Polykatianna (45 and 22); and Tomoceridae: Pogonognathellus flavescens (45 and 93). Two genera were only found at PC, Dicyrtomidae: Ptenothrix (31) and Entomobryidae: Lepidocyrtus (4). This is the first study to record abundance values of these high magnitudes for springtails captured with Malaise traps. Results are compared with previous studies at Mexican and French localities, respectively; Entomobryidae was the most abundant family captured with this method

Bayesian sequential data assimilation for COVID-19 forecasting

We introduce a Bayesian sequential data assimilation and forecasting method for non-autonomous dynamical systems. We applied this method to the current COVID-19 pandemic. It is assumed that suitable transmission, epidemic and observation models are available and previously validated. The transmission and epidemic models are coded into a dynamical system. The observation model depends on the dynamical system state variables and parameters, and is cast as a likelihood function. The forecast is sequentially updated over a sliding window of epidemic records as new data becomes available. Prior distributions for the state variables at the new forecasting time are assembled using the dynamical system, calibrated for the previous forecast. Epidemic outbreaks are non-autonomous dynamical systems depending on human behavior, viral evolution and climate, among other factors, rendering it impossible to make reliable long-term epidemic forecasts. We show our forecasting method’s performance using a SEIR type model and COVID-19 data from several Mexican localities. Moreover, we derive further insights into the COVID-19 pandemic from our model predictions. The rationale of our approach is that sequential data assimilation is an adequate compromise between data fitting and dynamical system prediction.

Clustering of food poverty among Mexican children: A spatial analysis

The aim of this study is to find out in which Mexican localities clusters of food poverty have formed in children, a problem that must be urgently addressed to improve the future of those individuals who suffer from it. This phenomenon has irreversible physical and cognitive repercussions. The idea that socio-economic conditions can be improved through the reduction of hunger is supported, and the tool to favour children is the implementation of targeted programmes in specific areas where this phenomenon has formed clusters and therefore requires more attention.In order to find food poverty clusters among Mexican children, the local indicators of spatial association (LISA) method is used mainly for the purpose of identifying regions where hunger has formed clusters.The results show that children living in the south of the country belong to the poorest population and food poverty clusters have formed in this area. It is concluded that even though current legislation favours the eradication of child poverty, no direct actions have been implemented to benefit children, which is why targeted programmes should be implemented in these areas to achieve this objective.

Paleontological research in Mexico: A brief account of current studies from the Sociedad Mexicana de Paleontología

This Special Issue entitled Paleontological studies developed in the Sociedad Mexicana de Paleontología, is an initiative of the “Sociedad Mexicana de Paleontología” (SOMEXPAL) in collaboration with the Journal of South American Earth Sciences (Elsevier), in order to highlight recent trends in the field carried out by members of this society. All diverse contributions cover all major research topics in Mexican paleontology such as: paleobotany, invertebrate paleontology, vertebrate paleontology, micropaleontology and geochemical analysis applied to paleontology. The recent paleontological studies here reported combine classical taxonomic descriptions coupled to software and digital innovations that produce a more complete paleobiological interpretation of fossils. This volume lists 24 original contributions from approximately 20 Mexican localities that roughly represents 15–20% of the most studied localities distributed in 10 states of Mexico. While this volume presents emblematic outcrops that continue to produce fresh fossil discoveries, some contributions incorporate new sedimentary settings from early Paleozoic through Quaternary environments waiting to be studied by young specialists. Although contributions concentrated in this volume are just a sample of the great variety of paleontological studies across Mexico, most articles critically address the use of fossils for paleoenvironmental reconstructions in several localities of Mexico. Finally, this special issue acknowledges the earlier work by pioneer paleontologists, and highlights at the same time, areas where paleontological data is rather scarce being great opportunities to carry out future research.

Four new species of Phrynus, Lamarck (Arachnida: Amblypygi) from Mexico.

Mexico is the country with the largest diversity of the genus Phrynus (Amblypygi: Phrynidae); however, many species could remain hidden due to the conservative morphology of the group. Two of the Mexican species, P. operculatus, and P. jalisco show enough variation, between populations from different localities, to be considered as possible species complexes. The scarce taxonomic information of these species and the few analyses of their variation could cause misidentifications and sub estimation of the diversity. Specimens morphologically similar to P. operculatus from different Mexican localities were analyzed, using characters from the male and female genitals. Four new species are described, presenting illustrations of SEM for the male genitals. Details of the morphologic variation in this group of species are discussed, as well as the usefulness of sexual characters like the size proportions, and sclerotization in the female gonopods, and ornaments in males, to improve the diagnoses of the Mexican Phrynus. The known distribution of P. operculatus is large in comparison with those of the other species, after the result of this research, the possibility that it is a larger species complex is evident, thus, it is necessary to increase the morphologic and genetic population studies in this group.

Answer to reply to C. Acosta Hospitaleche and M. Reguero (2020) additional Pelagornithidae remains from Seymour Island, Antarctica

This Special Issue entitled Paleontological studies developed in the Sociedad Mexicana de Paleontología, is an initiative of the “Sociedad Mexicana de Paleontología” (SOMEXPAL) in collaboration with the Journal of South American Earth Sciences (Elsevier), in order to highlight recent trends in the field carried out by members of this society. All diverse contributions cover all major research topics in Mexican paleontology such as: paleobotany, invertebrate paleontology, vertebrate paleontology, micropaleontology and geochemical analysis applied to paleontology. The recent paleontological studies here reported combine classical taxonomic descriptions coupled to software and digital innovations that produce a more complete paleobiological interpretation of fossils. This volume lists 24 original contributions from approximately 20 Mexican localities that roughly represents 15–20% of the most studied localities distributed in 10 states of Mexico. While this volume presents emblematic outcrops that continue to produce fresh fossil discoveries, some contributions incorporate new sedimentary settings from early Paleozoic through Quaternary environments waiting to be studied by young specialists. Although contributions concentrated in this volume are just a sample of the great variety of paleontological studies across Mexico, most articles critically address the use of fossils for paleoenvironmental reconstructions in several localities of Mexico. Finally, this special issue acknowledges the earlier work by pioneer paleontologists, and highlights at the same time, areas where paleontological data is rather scarce being great opportunities to carry out future research.

Description of the Neochoerus specimens from the Late Pleistocene (Rancholabrean) of Chiapas, and comments on the taxonomic identity of the fossil capybaras from other Mexican localities

Description of the Neochoerus specimens from the Late Pleistocene (Rancholabrean) of Chiapas, and comments on the taxonomic identity of the fossil capybaras from other Mexican localities

National report of blood lead levels and lead-glazed ceramics use in vulnerable children.

To estimate the prevalence of elevated (≥5.0μg /dL) blood lead levels (BLL) and its association with the use of lead glazed ceramics (LGC). In 2018, we measured capillary BLL in a representative sample of children 1 to 4 years old residing in Mexican localities under 100 000 inhabitants (Ensanut 100k). We inquired about use of LGC for food preparation and consumption. To estimate its association with BLL, multinomial logit models stratified by region were generated. The prevalence of elevated BLL levels was 21.8%. For the North, Central and South regions, the prevalence were 9.8, 20.7 and 25.8%, respectively. The association with use and frequency of LGC was highly significant and differential by region. Lead exposure remains a public health problem in Mexico, particularly in the Central and South regions, and is strongly associated with the use of LGC.

Food security in Mexican households in poverty, and its association with access, availability and consumption

To assess changes in the magnitude of food insecurity (FI) in Mexican households in poverty from 2012 to 2018 and to analyze the association of FI with the access, availability and consumption of food. Data on 4 464 households were drawn from the Encuesta Nacional de Salud y Nutrición in Mexican localities under 100 000 inhabitants (Ensanut 100k). We measured FI according to the Latin American and Caribbean Food Security Scale and analyzed food access and availability on the basis of food expenditures while consumption through dietary diversity among women. Using multiple logistic regression models, we estimated: the association between FI and expenditures for food groups, and the association between FI and dietary diversity. Moderate and severe FI remained stable at 43% from 2012 to 2018. Larger expenditures on sugar, oil and on eating out as well as meat and dairy products consumption were associated with a lower possibility of FI. It is important to integrate different dimensions of FI in order to reinforce its measurement and monitoring.

Genetic structure of Mexican lionfish populations in the southwest Gulf of Mexico and the Caribbean Sea.

The recent expansion of the invasive lionfish throughout the Western Hemisphere is one of the most extensively studied aquatic invasions. Molecular studies have improved our understanding of larval dispersal, connectivity, and biogeographical barriers among lionfish populations, but none have included Mexican localities, an important area for the larval dispersal of Pterois volitans through the Western Caribbean and the Gulf of Mexico. Here, we present a genetic analysis of lionfishes collected along Mexican coasts, examining their connectivity with other Caribbean localities (Belize, Cuba, Puerto Rico) and the role of ocean currents on population structure. We collected 213 lionfish samples from seven locations comprising four countries. To evaluate genetic structure, mitochondrial control region and nuclear inter-simple sequence repeat markers were used. We found that lionfish collected along Mexican coasts show a similar haplotype composition (H02 followed by H01 and H04) to other Caribbean locations, and the H03 rare haplotype was not found. Haplotype composition in the southwest Gulf of Mexico suggests a discontinuity between the southern and northern areas of the Gulf of Mexico. The southern area clustered more strongly to the Caribbean region, and this is supported by the complexity of water circulation in the semi-enclosed region of the Gulf of Mexico. Mitochondrial genetic diversity parameters show small values, whereas nuclear markers produce medium to high values. Only nuclear markers highlighted significant genetic differentiation between the southwest Gulf of Mexico and Caribbean region, confirming a phylogeographic break between both regions. Separate analysis of Caribbean locations indicates restricted larval exchange between southern and northern regions of the Mesoamerican Barrier Reef System, potentially in response to regional oceanographic circulation.

Promoting fruit, vegetable and simple water consumption among mothers and teachers of preschool children: An Intervention Mapping initiative

For preschool children, mothers and teachers are the principal models and promoters of fruit, vegetable and simple water consumption at home and school, respectively. However, the daily intake of these food and drink items falls below recommended standards among Mexican adults, posing a high risk of non-communicable diseases such as overweight and obesity across all age groups in the country. The objective of this article is to describe the design, implementation and evaluation of an educational initiative conducted in a Mexican locality with the aim of promoting the consumption of fruits, vegetables (FVs) and simple water (SW) among preschoolers through the influence of their mothers and teachers. We used the Intervention Mapping methodology with qualitative and quantitative components. Mothers attended eight theoretical and practical sessions and two school meetings, while teachers were offered two workshops. Our results revealed positive changes among both groups: participants took greater interest in healthy nutrition, increased their purchase, preparation and intake of FVs and SW and promoted their consumption. This confirms that it is possible to achieve favorable changes in eating habits among those who participate in educational initiatives in Mexico.

The Oldest Beetle and Bee Ichnofossils from Mexico and their Paleoenvironmental Implications

ABSTRACTSpecimens of Fictovichnus gobiensis, Celliforma curvata, Celliforma rosellii, Celliforma germanica and Celliforma isp. were collected from paleosol horizons in a fluviolacustrine succession near Santiago Yolomécatl town, in northwestern Oaxaca, southern Mexico. These ichnofossils represent the oldest evidence of beetles and bees in Mexican localities. K–Ar ages and the record of the equid Miohippus assiniboiensis, an index fossil, indicate that the age of the deposits is late Eocene. Based on the presence of the insect ichnofossils, pedogenic carbonate isotopes and mammal proxies, the inferred type of vegetation present in the study area was scrubland/woodland, within subhumid to subarid conditions.

Concentration of heavy metals in condensed atmospheric water vapor at three Mexican localities

The condensation of water vapor is a very useful technique in mitigating the scarcity of water resources for human consumption; however, the quality of this water must meet the highest standards to avoid becoming a health hazard. The present study quantifies trace elements such as As, Ba, Cu, Cd, Cr, Fe, Hg, Mn, Pb, and Zn, as well as pH and electrical conductivity (EC), in condensed atmospheric water vapor at three localities in Mexico. Atmospheric water vapor was condensed with an atmospheric water generator prototype. A total of 108 samples were obtained from three survey sites over the course of two seasons (wet and dry) during day/night shifts. The concentration of heavy metals was analyzed using inductively coupled plasma mass spectrometry. The pH and EC parameters were measured with a potentiometer/conductometer. We found Pb, Fe, and Cd in 91.66, 58.33, and 33% of the samples, respectively, at concentrations exceeding those permitted by the World Health Organization (WHO) for water intended for human consumption. Both pH and EC were within the limits established by the Department of Water Affairs of Namibia. The concentrations of trace metals in condensed atmospheric water vapor samples were within the maximum permissible limits determined by WHO for most elements analyzed in this study.