Genetic Overview of the Maya Populations: Mitochondrial DNA Haplogroups

We identified the mitochondrial DNA haplogroups A, B, C and D in 75 present-day Maya individuals, 24 Maya individuals of the colonial period and one pre-Columbian Maya individual from Quintana Roo, Mexico. We examined these data together with those of 21 Maya populations accounting for 647 present-day Maya individuals and 104 ancient Maya individuals. A demographic study based on the analysis of fertility and endogamy was carried out in two modern Maya populations to identify cultural factors that influence the mitochondrial haplogroup genetic diversity. Most present-day and ancient Maya populations show a distribution pattern of mitochondrial haplogroup frequencies A, C, B and D in decreasing order, with haplogroup D absent in several populations. Considering only modern Maya populations with at least 50 individuals analyzed, the present-day Tzotzil and Lacandon populations from Chiapas show the higher and lower genetic diversities, 0.706 and 0.025 respectively. Our results show small genetic differences between the Maya populations with exception of the present-day Tojolabal and Lacandon populations from Chiapas. The present-day Lacandon population from Chiapas is different to other Maya populations in showing almost only haplogroup A. This result suggests a long history of isolation and endogamy as well as a possible founder effect inside the Lacandonian rain-forest. The contemporary Tojolabal population is the only one with an unusual mitochondrial haplogroup pattern exhibiting a frequency of haplogroup B higher than A and the absence of haplogroup C. With a small sample size, the pre-Columbian Copan Maya show a high content of haplogroup C and a low frequency of haplogroup D. The genetic homogeneity of the Maya populations is indicative of a common origin and nearly continuous gene flow in the long-term within a general isolation of the whole group, conversely to the Nahua populations that had different origins. Our demographic study showed high fertility rates and high levels of endogamy in the present-day Maya populations from Quintana Roo here analyzed that are consistent with their general low genetic diversity. We propose that the genetic similarity among ancient and present-day Maya populations persists due to a strong sense of social cohesion and identity that impacts their marriage practices maintaining this cultural group isolated. These factors have constrained gene flow inside the Maya region and impeded the differentiation among the Maya. Discernment of genetic differentiation within the peninsula is constrained by the lack of sampling documentation in the literature

Búsqueda e identificación de DNA de treponema pallidum en restos óseos humanos prehispánicos de México, que muestran lesiones sugerentes de sífilis

Ciencias Biológica

Mitochondrial DNA Analysis of Mazahua and Otomi Indigenous Populations from Estado de México Suggests a Distant Common Ancestry

The indigenous Mazahua and Otomi have inhabited the same localities in Estado de México since pre-Columbian times. Their languages, Mazahua and Otomi, belong to the Oto-Manguean linguistic family, and although they share cultural traditions and a regional history that suggest close genetic relationships and common ancestry, the historical records concerning their origin are confusing. To understand the biological relationships between Mazahua and Otomi, we analyzed mitochondrial DNA (mtDNA) genetic variation. We identified the mtDNA haplogroups by restriction fragment length polymorphism typing and sequenced hypervariable region 1 of the mtDNA control region in 141 Mazahua and 100 Otomi. These results showed that Otomi exhibit a higher frequency of haplogroup A than B, whereas Mazahua exhibit the opposite pattern. In the Otomi EM population the most frequent subhaplogroups are, in order of frequency, A2, B2, and C1, whereas in the Mazahua 1 population they are B2, D1, and A2. The most frequent haplotypes (Ht) of haplogroups A and B are Ht2 (A) and Ht58 (B2g1) in Mazahua 1 and Ht8 (A2), Ht22 (A2ao1), and Ht53 (B2c2b) in Otomi EM. The genetic differences between the Mazahua 1 and Otomi EM suggest a distant shared ancestry and a moderate degree of maternal admixture that has not obscured the diffference of their mtDNA patterns. These unexpected results suggest the Mazahua and Otomi probably descend from the same group but separated very early and admixed with other Mesoamerican populations before their arrival in Central Mexico. The historical evidence of conflicting relations between the Mazahua and Otomi and the almost nonexistence of marriage between them could be responsible for maintaining only a moderate degree of maternal admixture

Genetic Relationships between Mesoamerican Ancient Populations and with American Greater Southwest and Caribbean Populations Close to Mesoamerican Borders

Mesoamerica is a cultural and geographic region with a northern boundary adjacent to the American Greater Southwest, meanwhile its southeastern boundary includes the Maya area, which is adjacent to the Caribbean. These regions are of interest to analyze genetic structure, ancestry and gene flow between the ancient populations. We identified the mitochondrial DNA haplogroups and haplotypes in 19 colonial and 10 pre-Columbian Maya from Xcaret and 6 Paquimé individuals. We analyzed our data together with 603 ancient individuals, 95 colonial and 502 pre-Columbian. The results show clear genetic differences between Mesoamerica, American Greater Southwest and Caribbean regions. High frequency of haplogroup A in Paquimé and Mine Canyon and the distribution of their haplotypes in the networks suggest that these populations are probably genetically related with both, Mesoamerica and the American Greater Southwest. The genetic structure of the Maya is due to common ancestry and it was maintained by geographic isolation and gene flow mostly between Mayan populations. The Spanish conquest did not change this structure in the Maya from Xcaret, Quintana Roo. Although populations from Central Mexico are not genetically homogenous, they are clearly different to Maya. Teotihuacan and Cholula were contemporary cities that allied to control the region, however they show genetic differences that could be related with a distant common ancestry; they probably descended from the same group but separated very early, before their arrival to Central Mexico

Análisis del DNA mitocondrial antiguo y contemporáneo: un acercamiento a las relaciones genéticas en las poblaciones indígenas de Mesoamérica

En el presente estudio analizamos los haplogrupos A, B, C y D del acido desoxirribonucleico mitocondrial (mtdna) en 108 individuos contemporaneos mazahuas y 68 otomies del Estado de Mexico. El objetivo del analisis es identificar las relaciones genéticas entre estos grupos y compararlos con otras poblaciones antiguas y contemporaneas de Mexico. Los grupos poblacionales mazahua y otomi habitan en los mismos municipios del Estado de Mexico, hablan lenguajes que pertenecen a la familia linguistica oto-mangue, comparten aspectos culturales y una historia en comun. Los resultados mostraron que el haplogrupo B es el más frecuente en los mazahuas y el A en los otomies. El haplogrupo C presenta frecuencias similares en ambos grupos. La poblacion otomi presenta una baja frecuencia del haplogrupo D e incluye individuos que no presentaron ninguno de los cuatro haplogrupos del mtdna, mientras que todos los individuos de la poblacion mazahua pertenecieron a uno de los cuatro haplogrupos estudiados. Las poblaciones mazahua y otomi del actual Estado de Mexico son estadísticamente diferentes por el metodo de ji cuadrada (p ? 0.05). El analisis de componentes principales basado en las frecuencias de los cuatro haplogrupos del mtdna sugiere que entre ambos grupos poblacionales no ha habido flujo genico por via materna o ha sido muy escaso

Demographic history and genetic structure in pre-Hispanic Central Mexico

International audienceAridoamerica and Mesoamerica are two distinct cultural areas in northern and central Mexico, respectively, that hosted numerous pre-Hispanic civilizations between 2500 BCE and 1521 CE. The division between these regions shifted southward because of severe droughts ~1100 years ago, which allegedly drove a population replacement in central Mexico by Aridoamerican peoples. In this study, we present shotgun genome-wide data from 12 individuals and 27 mitochondrial genomes from eight pre-Hispanic archaeological sites across Mexico, including two at the shifting border of Aridoamerica and Mesoamerica. We find population continuity that spans the climate change episode and a broad preservation of the genetic structure across present-day Mexico for the past 2300 years. Lastly, we identify a contribution to pre-Hispanic populations of northern and central Mexico from two ancient unsampled “ghost” populations

Proyecto De Tesis I - CI186 - 202102

Descripción: Curso de especialidad en la carrera de ingeniería civil de carácter teórico-práctico dirigido a los estudiantes del 9no ciclo. El curso Proyecto de Tesis I busca que los estudiantes de Ingeniería Civil apliquen sus capacidades adquiridas durante todos sus estudios, en completar una investigación, que plantea resolver una problemática en una de las líneas de la carrera. Con la ayuda de un docente asesor especialista en el tema lograran redactar el informe de tesis al 50%, este informe será revisado por otro docente especialista que proporciona sugerencias de mejoras a la investigación. Por último, los estudiantes exponen ante un jurado especialista sus resultados quienes evalúan y también hacen sugerencia de mejoras a la investigación. Propósito: En el Perú actualmente existe un gran número de estudiantes de Ingeniería Civil que no cuentan con el título profesional, por no realizar la tesis de investigación, lo cual disminuye significativamente su desarrollo profesional y sus oportunidades laborales. El curso de proyecto de Tesis 1 permite que los estudiantes puedan desarrollar el 50% de la Tesis de investigación, siendo la misma certificada por un asesor y un jurado evaluador. Contribuye con el desarrollo de las competencias generales de Pensamiento Crítico, Razonamiento Cuantitativo, Pensamiento Innovador y las competencias específicas 1, 4 y 7 de ABET, todas a nivel de logro 3

Proyecto De Tesis I - CI186 - 202101

Descripción: Curso de especialidad en la carrera de ingeniería civil de carácter teórico-práctico dirigido a los estudiantes del 9no ciclo. El curso Proyecto de Tesis I busca que los estudiantes de Ingeniería Civil apliquen sus capacidades adquiridas durante todos sus estudios, en completar una investigación, que plantea resolver una problemática en una de las líneas de la carrera. Con la ayuda de un docente asesor especialista en el tema lograran redactar el informe de tesis al 50%, este informe será revisado por otro docente especialista que proporciona sugerencias de mejoras a la investigación. Por último, los estudiantes exponen ante un jurado especialista sus resultados quienes evalúan y también hacen sugerencia de mejoras a la investigación. Propósito: En el Perú actualmente existe un gran número de estudiantes de Ingeniería Civil que no cuentan con el título profesional, por no realizar la tesis de investigación, lo cual disminuye significativamente su desarrollo profesional y sus oportunidades laborales. El curso de proyecto de Tesis 1 permite que los estudiantes puedan desarrollar el 50% de la Tesis de investigación, siendo la misma certificada por un asesor y un jurado evaluador. Contribuye con el desarrollo de las competencias generales de Pensamiento Crítico, Razonamiento Cuantitativo, Pensamiento Innovador y las competencias específicas 1, 4 y 7 de ABET, todas a nivel de logro 3

The High-Altitude water cherenkov (HAWC) observatory in México: The primary detector

The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the Milagro experiment in using ground-based water Cherenkov detectors for gamma-ray astronomy. HAWC is located on the Sierra Negra volcano in México at an elevation of 4100 meters above sea level. The completed HAWC observatory principal detector (HAWC) consists of 300 closely spaced water Cherenkov detectors, each equipped with four photomultiplier tubes to provide timing and charge information to reconstruct the extensive air shower energy and arrival direction. The HAWC observatory has been optimized to observe transient and steady emission from sources of gamma rays within an energy range from several hundred GeV to several hundred TeV. However, most of the air showers detected are initiated by cosmic rays, allowing studies of cosmic rays also to be performed. This paper describes the characteristics of the HAWC main array and its hardware.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Físic