The genetic scenario of Mercheros: an under-represented group within the Iberian Peninsula

Background The general picture of human genetic variation has been vastly depicted in the last years, yet many populations remain broadly understudied. In this work, we analyze for the first time the Merchero population, a Spanish minority ethnic group that has been scarcely studied and historically persecuted. Mercheros have been roughly characterised by an itinerant history, common traditional occupations, and the usage of their own language. Results Here, we examine the demographic history and genetic scenario of Mercheros, by using genome-wide array data, whole mitochondrial sequences, and Y chromosome STR markers from 25 individuals. These samples have been complemented with a wide-range of present-day populations from Western Eurasia and North Africa. Our results show that the genetic diversity of Mercheros is explained within the context of the Iberian Peninsula, evidencing a modest signal of Roma admixture. In addition, Mercheros present low genetic isolation and intrapopulation heterogeneity. Conclusions This study represents the first genetic characterisation of the Merchero population, depicting their fine-scale ancestry components and genetic scenario within the Iberian Peninsula. Since ethnicity is not only influenced by genetic ancestry but also cultural factors, other studies from multiple disciplines are needed to further explore the Merchero population. As with Mercheros, there is a considerable gap of underrepresented populations and ethnic groups in publicly available genetic data. Thus, we encourage the consideration of more ethnically diverse population panels in human genetic studies, as an attempt to improve the representation of human populations and better reconstruct their fine-scale history.

Assessment of autosomal and male DNA extracted from casework samples using Casework Direct Kit, Custom and Maxwell 16 System DNA IQ Casework Pro Kit for autosomal-STR and Y-STR profiling

Short repetitive regions in autosomal and Y chromosomes known as short tandem repeats (STRs) are currently used for DNA profiling in crime investigations. However, DNA profiling requires a sufficient quality and quantity of DNA template, which is often not obtained from trace evidence or degraded biological samples collected at the scene of a crime. Here, we assessed autosomal and male DNA components extracted from crime scene and mock casework samples using the Casework Direct Kit, Custom and compared the results against those obtained by extraction of matching samples using well-established Maxwell 16 System DNA IQ Casework Pro Kit. The quantity and quality of extracted DNA obtained using both Casework Direct Kit, Custom and Maxwell 16 System DNA IQ Casework Pro Kit were analyzed using PowerQuant Systems followed by autosomal and Y-chromosome STR profiling using GlobalFiler Express PCR Amplification Kit and PowerPlex Y23 System, respectively. Our results showed that the Casework Direct Kit and Maxwell 16 DNA IQ Casework Pro Kit have more or less equal capacity to extract inhibitor free DNA, but that the latter produces slightly better quality and more DNA template and subsequently higher numbers of STR allele calls for autosomal and Y-STR analyses. Nonetheless, the Casework Direct Kit, Custom is the quicker and cheaper option for extraction of good, clean DNA from high content material and might best be used for extraction of reference samples. Such reference DNA samples typically come from buccal swabs or freshly drawn blood. So, in general, they can confidently be expected to have a high nucleic acid content and to be inhibitor-free.

О происхождении отцовских линий популяции саха: сравнительный анализ данных популяционной генетики / древней ДНК, археологических и исторических исследований

Саха (якуты) являются самым северным и многочисленным тюркоязычным народом Северо-Восточной Сибири. Согласно широко распространенным среди саха легендам, прародителями народа являются Эллэй и Омогой, прибывшие на Среднюю Лену из азиатской степи. Археологические находки и исследования древних ДНК позволяют констатировать: персонажи Эллэя и Омогоя – реальные исторические личности, тесно связанные с этногенезом саха. Цель настоящего исследования – определение генетической «подписи» (биомаркеров) родовых линий популяции саха, в том числе легендарных Эллэя и Омогоя по их отцовским линиям. В данном исследовании впервые определены гаплогруппа и гаплотип STR-локусов Y-хромосомы родовой линии Эллэя на основе исследования его вероятного прямого потомка, генеалогия которого установлена по достоверным архивным документам и опубликованным источникам научных исследований. Анализ 367 гаплотипов STR-локусов Y-хромосомы популяции саха, собранные из литературных и других источников с использованием поисковых инструментов Y-chromosome STR Haplotype Reference Database (YHRD), показал, что отцовские линии саха состоят из 6 основных кластеров расширения, каждый из которых соответствует древнему клану. Среди современной популяции саха наиболее распространенный гаплотип действительно был представлен линией вероятного потомка легендарного Эллэя. В настоящей работе представлены данные, подтверждающие его киданьское происхождение. Как было показано ранее, отцовские линии саха оказались очень гомогенными и демонстрировали признаки сильного узкого места в популяции. Генетические и археологические данные хорошо согласуются с историческими повествованиями саха, в которых, по крайней мере, с точки зрения отцовской линии, только несколько человек, возможно, прибыли из степей Азии и имели репродуктивный успех среди автохтонного населения, что привело к сегодняшнему разнообразию Y-хромосомы популяции.

On the origins of the Sakhas' paternal lineages: Reconciliation of population genetic / ancient DNA data, archaeological findings and historical narratives

Sakhas are Turkic-speaking people from Northeastern Siberia, constituting the largest ethnic population in Yakutia. According to popular legends, two heroes who arrived from the Asian Steppe during the late medieval ages, namely Elley Bootur and Omogoy Baay, are the progenitors of all Sakhas. While there is ample historical evidence towards the existence of such legendary characters, archaeological findings and ancient DNA studies provide further insights on actual Sakha ethnogenesis. This study aims to establish the genetic basis of the legendary characters Elley and Omogoy, at least through their paternal lineages, and then to reveal the prevalence of these Y-chromosomes among the contemporary Yakut population. To this end, an attempt was made to delineate fact from fiction with respect to the Sakhas’ paternal lineages through a reconciliation of population genetics data on contemporary and ancient Sakhas, along with archaeological evidence and well-recorded historical narratives. To achieve this, 17-loci Y-chromosomal STR and haplogroup analyses were conducted on a contemporary Sakha who was presumably a direct descendant of Elley’s paternal line. Furthermore, 367 Sakha Y-chromosomal STR haplotypes were compiled from the literature and elsewhere, and searched against the Y-chromosome STR Haplotype Reference Database to find potential matches with non-Sakha populations. Sakhas’ paternal lineages were found to comprise 6 major descent clusters, each corresponding to an ancient clan. The most prevalent haplotype indeed corresponded to that of the contemporary Elley descendant. Furthermore, data presented in the current work suggests a Khitan origin for this paternal line. As shown before, Sakhas’ paternal lineages were found to be very homogenous and exhibit signs of a strong population bottleneck. Reconciled genetic and archaeological data agree well with Sakhas’ historical narratives, whereby, at least from a paternal lineage perspective, only a few individuals may have arrived from Central Asia and had reproductive success that led to the Sakha Y-chromosomal diversity today.