Genetic variation in prehistoric Sardinia

We sampled teeth from 53 ancient Sardinian (Nuragic) individuals who lived in the Late Bronze Age and Iron Age, between 3,430 and 2,700 years ago. After eliminating the samples that, in preliminary biochemical tests, did not show a high probability to yield reproducible results, we obtained 23 sequences of the mitochondrial DNA control region, which were associated to haplogroups by comparison with a dataset of modern sequences. The Nuragic samples show a remarkably low genetic diversity, comparable to that observed in ancient Iberians, but much lower than among the Etruscans. Most of these sequences have exact matches in two modern Sardinian populations, supporting a clear genealogical continuity from the Late Bronze Age up to current times. The Nuragic populations appear to be part of a large and geographically unstructured cluster of modern European populations, thus making it difficult to infer their evolutionary relationships. However, the low levels of genetic diversity, both within and among ancient samples, as opposed to the sharp differences among modern Sardinian samples, support the hypothesis of the expansion of a small group of maternally related individuals, and of comparatively recent differentiation of the Sardinian gene pools. © Springer-Verlag 2007

Bringing together approaches to reporting on within species genetic diversity

1. Genetic diversity is one of the three main levels of biodiversity recognised in the Convention on Biological Diversity (CBD). Fundamental for species adaptation to environmental change, genetic diversity is nonetheless under-reported within global and national indicators. When it is reported, the focus is often narrow and confined to domesticated or other commercial species. 2. Several approaches have recently been developed to address this shortfall in reporting on genetic diversity of wild species. While multiplicity of approaches is helpful in any development process, it can also lead to confusion among policy makers and heighten a perception that conservation genetics is too abstract to be of use to organisations and governments. 3. As the developers of five of the different approaches, we have come together to explain how various approaches relate to each other and propose a scorecard, as a unifying reporting mechanism for genetic diversity. 4. Policy implications. We believe the proposed combined approach captures the strengths of its components and is practical for all nations and subnational governments. It is scalable and can be used to evaluate species conservation projects as well as genetic conservation projects.ISSN:0021-8901ISSN:1365-266

Mitochondrial echoes of first settlement and genetic continuity in El Salvador

Background: From Paleo-Indian times to recent historical episodes, the Mesoamerican isthmus played an important role in the distribution and patterns of variability all around the double American continent. However, the amount of genetic information currently available on Central American continental populations is very scarce. In order to shed light on the role of Mesoamerica in the peopling of the New World, the present study focuses on the analysis of the mtDNA variation in a population sample from El Salvador. Methodology/Principal Findings: We have carried out DNA sequencing of the entire control region of the mitochondrial DNA (mtDNA) genome in 90 individuals from El Salvador. We have also compiled more than 3,985 control region profiles from the public domain and the literature in order to carry out inter-population comparisons. The results reveal a predominant Native American component in this region: by far, the most prevalent mtDNA haplogroup in this country (at ~90%) is A2, in contrast with other North, Meso- and South American populations. Haplogroup A2 shows a star-like phylogeny and is very diverse with a substantial proportion of mtDNAs (45%; sequence range 16090–16365) still unobserved in other American populations. Two different Bayesian approaches used to estimate admixture proportions in El Salvador shows that the majority of the mtDNAs observed come from North America. A preliminary founder analysis indicates that the settlement of El Salvador occurred about 13,400±5,200 Y.B.P.. The founder age of A2 in El Salvador is close to the overall age of A2 in America, which suggests that the colonization of this region occurred within a few thousand years of the initial expansion into the Americas. Conclusions/Significance: As a whole, the results are compatible with the hypothesis that today's A2 variability in El Salvador represents to a large extent the indigenous component of the region. Concordant with this hypothesis is also the observation of a very limited contribution from European and African women (~5%). This implies that the Atlantic slave trade had a very small demographic impact in El Salvador in contrast to its transformation of the gene pool in neighbouring populations from the Caribbean facade

A multistep process for the dispersal of a Y chromosomal lineage in the Mediterranean area

Tn this work we focus on a microsatellite-defined Y-chromosomal lineage (network 1.2) identified by us and reported in previous studies, whose geographic distribution and antiquity appear to be compatible with the Neolithic spread of farmers. Here, we set network 1.2 in the Y-chromosomal phylogenetic tree, date it with respect to other lineages associated with the same movements by other authors, examine its diversity by means of tri- and tetranucleotide loci and discuss the implications hi reconstructing the spread of this group of chromosomes in the Mediterranean area. Our results define a tripartite phylogeny wit-bin HG 9 (Rosser et al. 2000) with the deepest branching defined by alleles T (Haplogroup Eu 10) or G (Haplogroup Eu9) at M172 (Semino et al. 2000), and a subsequent branching within Eu9 defined by network 1.2. Population distributions of HG 9 and network 1.2 show that their occurrence in the surveyed area is not due to the spread of people from a single parental population but, rather, to a process punctuated by at least two phases. Our data identify the wide area of the Balkans, Aegean and Anatolia as the possible homeland harbouring the largest variation within network 1.2. The use of recently proposed tests based on the stepwise mutation model suggests that its spread was associated to a population expansion, xvith a high rate of male gene flow in the Turkish Greek area

Genetic diversity Goals and Targets have improved, but remain insufficient for clear implementation of the post-2020 global biodiversity framework

Genetic diversity among and within populations of all species is necessary for people and nature to survive and thrive in a changing world. Over the past three years, commitments for conserving genetic diversity have become more ambitious and specific under the Convention on Biological Diversity’s (CBD) draft post-2020 global biodiversity framework (GBF). This Perspective article comments on how goals and targets of the GBF have evolved, the improvements that are still needed, lessons learned from this process, and connections between goals and targets and the actions and reporting that will be needed to maintain, protect, manage and monitor genetic diversity. It is possible and necessary that the GBF strives to maintain genetic diversity within and among populations of all species, to restore genetic connectivity, and to develop national genetic conservation strategies, and to report on these using proposed, feasible indicators

Genetic characterization and phylogeography of the wild boar Sus scrofa introduced into Uruguay

The European wild boar Sus scrofa was first introduced into Uruguay, in southern South America during the early decades of the last century. Subsequently, and starting from founder populations, its range spread throughout the country and into the neighbouring Brazilian state Rio Grande do Sul. Due to the subsequent negative impact, it was officially declared a national pest. The main aim in the present study was to provide a more comprehensive scenario of wild boar differentiation in Uruguay, by using mtDNA markers to access the genetic characterization of populations at present undergoing rapid expansion. A high level of haplotype diversity, intermediate levels of nucleotide diversity and considerable population differentiation, were detected among sampled localities throughout major watercourses and catchment dams countrywide. Phylogenetic analysis revealed the existence of two different phylogroups, thereby reflecting two deliberate introduction events forming distantly genetic lineages in local wild boar populations. Our analysis lends support to the hypothesis that the invasive potential of populations emerge from introgressive hybridization with domestic pigs. On taking into account the appreciable differentiation and reduced migration between locales in wild boar populations, management strategies could be effective if each population were to be considered as a single management unit