No abstract

On the basis of distinct lines of evidence, detailed reconstructions of the Holocene population history of the Sabana de Bogotá (SB) region, Northern South America, have been performed. Currently, there exist two competing models that support temporal continuity or, alternatively, divergence. Despite recent research that lends support to the population discontinuity model, several discrepancies remain, calling for other kinds of evidences to be explored for a more detailed picture of Holocene biocultural evolution.In this study, we analyze the mitochondrial genetic diversity of 30 individuals (including 15 newly reported complete mitochondrial genomes) recovered from several archaeological sites spanning from the late Pleistocene (12,164 cal BP) until the final late Holocene (2,751 cal BP) along with published data from the region dating ~9,000-550 cal BP in order to investigate diachronic genetic change. Genetic diversity and distance indices were calculated, and demographic models tested in an approximate Bayesian computation (ABC) framework to evaluate whether patterns of genetic affinities of the SB prehispanic populations support genetic continuity or discontinuity. The results show that mitochondrial genomes of the complete dataset fall within the Native American haplogroups A2, B2, C1b, D1 and D4h3a. Haplotype and nucleotide diversity declined over time with further evidence of genetic drift and remarkable reduction of genetic diversity during the final late Holocene. Inter-population distances and the exact test of population differentiation, as well as demographic simulations show no population differentiation and population continuity over time. Consequently, based on the analyzed data, we cannot reject the genetic continuity in the SB region as a plausible population history scenario. However, the restriction of the analyses to the Hyper Variable Region 1 of the mitochondrial genome, and the very low sample size both constitute significant limitations to infer evolutionary history.

Introducción. A diferencia de otro tipo de investigaciones, el análisis de ADN antiguo (ADNa) requiere la implementación de condiciones metodológicas y de infraestructura especializadas que garanticen la autenticidad de los resultados. Uno de los criterios de autenticidad para este tipo de muestras es la cuantificación del material genético, en la cual es común el uso de la reacción en cadena de la polimerasa (PCR) cuantitativa en tiempo real, por su sensibilidad y especificidad. La implementación de estas metodologías y de las condiciones necesarias para el cumplimiento de los requisitos de autenticidad hace que este tipo de investigación sea dispendioso y costoso. Objetivo. Generar una estrategia de cuantificación del ADN mitocondrial de muestras seriamente degradadas mediante un sistema sencillo y de fácil implementación. Materiales y métodos. El sistema se basa en el uso de iniciadores que posibilitan la amplificación específica de fragmentos cortos del ADN mitocondrial. La posterior purificación de este fragmento permite generar una curva estándar con concentraciones acordes al estado de degradación de la muestra. Resultados. Se detectó ADN antiguo proveniente de restos óseos y tejidos momificados de diferentes fechas. Además, el sistema permitió detectar la presencia de agentes inhibidores del ADN. Conclusión. La implementación de la estrategia aquí planteada es sencilla, puede reducir los costos de la investigación y, además, permite la detección de ADNa en muestras muy degradadas, así como la discriminación entre las muestras que no poseen material genético y aquellas que presentan agentes inhibidores.Palabras clave: ADN, ADN mitocondrial, reacción en cadena de la polimerasa. doi: http://dx.doi.org/10.7705/biomedica.v36i3.3098Real-time quantification to analyze historical Colombian samples detecting a short fragment of hypervariable region II of mitochondrial DNA Introduction: Unlike other molecular biology studies, the analysis of ancient DNA (aDNA) requires special infrastructure and methodological conditions to guarantee the quality of the results. One of the main authenticity criteria is DNA quantification, where quantitative real-time PCR is often used given its sensitivity and specificity. Nevertheless, the implementation of these conditions and methodologies to fulfill authenticity criteria imply higher costs. Objective: To develop a simple and less costly method for mitochondrial DNA quantification suitable for highly degraded samples. Materials and methods:The proposed method is based on the use of mini-primers for the specific amplification of short fragments of mitochondrial DNA. The subsequent purification of these amplified fragments allows a standard curve to be constructed with concentrations in accordance to the state of degradation of the samples. Results: The proposed method successfully detected DNA from ancient samples including bone remains and mummified tissue. DNA inhibitory substances were also detected. Conclusion:The proposed method represents a simpler and cost-effective way to...

On the basis of distinct lines of evidence, detailed reconstructions of the Holocene population history of the Sabana de Bogotá (SB) region, Northern South America, have been performed. Currently, there exist two competing models that support temporal continuity or, alternatively, divergence. Despite recent research that lends support to the population discontinuity model, several discrepancies remain, calling for other kinds of evidences to be explored for a more detailed picture of Holocene biocultural evolution.In this study, we analyze the mitochondrial genetic diversity of 30 individuals (including 15 newly reported complete mitochondrial genomes) recovered from several archaeological sites spanning from the late Pleistocene (12,164 cal BP) until the final late Holocene (2,751 cal BP) along with published data from the region dating ~9,000-550 cal BP in order to investigate diachronic genetic change. Genetic diversity and distance indices were calculated, and demographic models tested in an approximate Bayesian computation (ABC) framework to evaluate whether patterns of genetic affinities of the SB prehispanic populations support genetic continuity or discontinuity. The results show that mitochondrial genomes of the complete dataset fall within the Native American haplogroups A2, B2, C1b, D1 and D4h3a. Haplotype and nucleotide diversity declined over time with further evidence of genetic drift and remarkable reduction of genetic diversity during the final late Holocene. Inter-population distances and the exact test of population differentiation, as well as demographic simulations show no population differentiation and population continuity over time. Consequently, based on the analyzed data, we cannot reject the genetic continuity in the SB region as a plausible population history scenario. However, the restriction of the analyses to the Hyper Variable Region 1 of the mitochondrial genome, and the very low sample size both constitute significant limitations to infer evolutionary history.

No abstract