Y Haplogroup Diversity of the Dominican Republic: Reconstructing the Effect of the European Colonization and the Trans-Atlantic Slave Trades

The Dominican Republic is one of the two countries on the Hispaniola island, which is part of the Antilles. Hispaniola was affected by the European colonization and massive deportation of African slaves since the XVI century and these events heavily shaped the genetic composition of the present-day population. To shed light about the effect of the European rules, we analyzed 92 single nucleotide polymorphisms on the Y chromosome in 182 Dominican individuals from three different locations. The Dominican Y haplogroup composition was characterized by an excess of northern African/European lineages (59%), followed by the African clades (38%), whereas the Native-American lineages were rare (3%). The comparison with the mitochondrial DNA variability, dominated by African clades, revealed a sex-biased admixture pattern, in line with the colonial society dominated by European men. When other Caribbean and non-Caribbean former colonies were also considered, we noted a difference between territories under a Spanish rule (like the Dominican Republic) and British/French rule, with the former characterized by an excess of European Y lineages reflecting the more permissive Iberian legislation about mixed people and slavery. Finally, we analyzed the distribution in Africa of the Dominican lineages with a putative African origin, mainly focusing on central and western Africa, which were the main sources of African slaves. We found that most (83%) of the African lineages observed in Santo Domingo have a central African ancestry, suggesting that most of the slaves were deported from regions.

Commensalism outweighs phylogeographical structure in its effect on phenotype of a Sudanian savanna rodent

The murid rodent Praomys daltoni is widespread in Sudanian savanna and woodlands of West Africa, and previous study of mitochondrial DNA variability suggested that it encompasses the phenotypically (small, grey-bellied) and ecologically (commensal) distinct form, Praomys derooi. Here, we comprehensively examined the genetic and morphological diversity within the complex. Six mitochondrial lineages showed a fine-scale phylogeographical pattern, whereas delimitation based on nuclear loci pooled four of them into a single widespread unit. A newly discovered lineage from southern Mauritania stands apart from the rest of the complex and might represent an unrecognized species. At the same time, the internal position of P. derooi (C2 mitochondrial lineage) was confirmed by the multilocus analysis. The magnitude of genetic distances between major phylogeographical lineages was typical for interspecific divergence in other clades of Praomys, despite the little differences among them in morphology (skull and upper molar row shapes). The most pronounced morphological shift was associated with a transition to commensalism, especially in P. derooi, but also in other lineages. This makes the whole complex a suitable model for the study of phenotypic novelty, the evolution of commensalism and conditions for ecological speciation.

Environmental factors modulated ancient mitochondrial DNA variability and the prevalence of rheumatic diseases in the Basque Country

Among the factors that would explain the distribution of mitochondrial lineages in Europe, climate and diseases may have played an important role. A possible explanation lies in the nature of the mitochondrion, in which the energy generation process produces reactive oxygen species that may influence the development of different diseases. The present study is focused on the medieval necropolis of San Miguel de Ereñozar (13th–16th centuries, Basque Country), whose inhabitants presented a high prevalence of rheumatic diseases and lived during the Little Ice Age (LIA). Our results indicate a close relationship between rheumatic diseases and mitochondrial haplogroup H, and specifically between spondyloarthropathies and sub-haplogroup H2. One possible explanation may be the climate change that took place in the LIA that favoured those haplogroups that were more energy-efficient, such as haplogroup H, to endure lower temperatures and food shortage. However, it had a biological trade-off: the increased risk of developing rheumatic diseases.

Nucleotide diversity of Cyt b gene in drosophila subobscura Collin

Mitochondrial DNA variability of Drosophila subobscura Collin from Southeastern Serbia was studied with respect to Restriction Site Analysis (RSA) of complete mitochondrial genome and the nucleotide sequence of Cytochrome b (Cyt b) gene. The aim was to shed more light on the evolutionary forces that shape mtDNA variation of this species. Samples were collected from two sites in the foothills of the Balkan Mountains. No genetic differentiation was found between groups and most of the variation was observed within them. Restriction analysis revealed two main haplotypes and several rare ones. The sequencing of Cyt b gene showed larger number of haplotypes, among which, one is being the most common. The majority of singletons differed from the most frequent haplotype by one nucleotide change. Although some of the observed nucleotide differences may affect their host?s fitness, the observed pattern of variation is consistent with the seasonal fluctuations in population size.

Genetic insights into the social organisation of the Avar period elite in the 7th century AD Carpathian Basin

After 568 AD the Avars settled in the Carpathian Basin and founded the Avar Qaganate that was an important power in Central Europe until the 9th century. Part of the Avar society was probably of Asian origin, however the localisation of their homeland is hampered by the scarcity of historical and archaeological data.Here, we study mitogenome and Y chromosomal STR variability of twenty-six individuals, a number of them representing a well-characterised elite group buried at the centre of the Carpathian Basin more than a century after the Avar conquest.The studied group has maternal and paternal genetic affinities to several ancient and modern East-Central Asian populations. The majority of the mitochondrial DNA variability represents Asian haplogroups (C, D, F, M, R, Y and Z). The Y-STR variability of the analysed elite males belongs only to five lineages, three N-Tat with mostly Asian parallels and two Q haplotypes. The homogeneity of the Y chromosomes reveals paternal kinship as a cohesive force in the organisation of the Avar elite strata on both social and territorial level. Our results indicate that the Avar elite arrived in the Carpathian Basin as a group of families, and remained mostly endogamous for several generations after the conquest.