Genetic Diversity In Europe Research Articles

Demographic events and evolutionary forces shaping European genetic diversity.

Europeans have been the focus of some of the largest studies of genetic diversity in any species to date. Recent genome-wide data have reinforced the hypothesis that present-day European genetic diversity is strongly correlated with geography. The remaining challenge now is to understand more precisely how patterns of diversity in Europe reflect ancient demographic events such as postglacial expansions or the spread of farming. It is likely that recent advances in paleogenetics will give us some of these answers. There has also been progress in identifying specific segments of European genomes that reflect adaptations to selective pressures from the physical environment, disease, and dietary shifts. A growing understanding of how modern European genetic diversity has been shaped by demographic and evolutionary forces is not only of basic historical and anthropological interest but also aids genetic studies of disease.

Genetic divergence and evidence for sympatric host-races in the highly polyphagous brown tail moth, Euproctis chrysorrhoea (Lepidoptera: Erebidae)

The brown tail moth (BTM) Euproctis chrysorrhoea (Linnaeus 1758) (Lepidoptera: Erebidae) is a forest and ornamental pest in Europe and the United States. Its extreme polyphagy, and documented phenological shift associated with host use suggest the presence of distinct host-races. To test this hypothesis, we sampled BTM infesting different host species in several locations along its distribution, and used DNA sequence data (a total of 1,672 bp from cytochrome c oxidase subunit I, elongation factor 1-alpha, and wingless) to produce haplotype networks and reconstruct the phylogenetic relationships between individuals. Population genetic diversity indices pointed out a higher genetic diversity in Europe, particularly in the samples from southern Spain and southern England. Lower F ST values were found between geographically closer populations when compared to more distant ones, but analyses of molecular variance and Mantel tests failed to reveal geographically associated genetic differentiation. However, haplotype networks and phylogenetic reconstructions revealed a previously unknown genetic differentiation within the BTM, with one lineage circumscribed to southern Europe. Although BTM haplotypes did not cluster according to their host plant, host-associated haplotypes were observed within certain geographic regions. Hence, our data support the existence of host-races of BTM within southern Spain and southern England, where populations from different hosts occur in sympatry.

Ancient DNA Reveals Key Stages in the Formation of Central European Mitochondrial Genetic Diversity

The processes that shaped modern European mitochondrial DNA (mtDNA) variation remain unclear. The initial peopling by Palaeolithic hunter-gatherers ~42,000 years ago and the immigration of Neolithic farmers into Europe ~8000 years ago appear to have played important roles but do not explain present-day mtDNA diversity. We generated mtDNA profiles of 364 individuals from prehistoric cultures in Central Europe to perform a chronological study, spanning the Early Neolithic to the Early Bronze Age (5500 to 1550 calibrated years before the common era). We used this transect through time to identify four marked shifts in genetic composition during the Neolithic period, revealing a key role for Late Neolithic cultures in shaping modern Central European genetic diversity.

Population structure and cultural geography of a folktale in Europe

Despite a burgeoning science of cultural evolution, relatively little work has focused on the population structure of human cultural variation. By contrast, studies in human population genetics use a suite of tools to quantify and analyse spatial and temporal patterns of genetic variation within and between populations. Human genetic diversity can be explained largely as a result of migration and drift giving rise to gradual genetic clines, together with some discontinuities arising from geographical and cultural barriers to gene flow. Here, we adapt theory and methods from population genetics to quantify the influence of geography and ethnolinguistic boundaries on the distribution of 700 variants of a folktale in 31 European ethnolinguistic populations. We find that geographical distance and ethnolinguistic affiliation exert significant independent effects on folktale diversity and that variation between populations supports a clustering concordant with European geography. This pattern of geographical clines and clusters parallels the pattern of human genetic diversity in Europe, although the effects of geographical distance and ethnolinguistic boundaries are stronger for folktales than genes. Our findings highlight the importance of geography and population boundaries in models of human cultural variation and point to key similarities and differences between evolutionary processes operating on human genes and culture.

A genome-wide analysis of populations from European Russia reveals a new pole of genetic diversity in northern Europe.

Several studies examined the fine-scale structure of human genetic variation in Europe. However, the European sets analyzed represent mainly northern, western, central, and southern Europe. Here, we report an analysis of approximately 166,000 single nucleotide polymorphisms in populations from eastern (northeastern) Europe: four Russian populations from European Russia, and three populations from the northernmost Finno-Ugric ethnicities (Veps and two contrast groups of Komi people). These were compared with several reference European samples, including Finns, Estonians, Latvians, Poles, Czechs, Germans, and Italians. The results obtained demonstrated genetic heterogeneity of populations living in the region studied. Russians from the central part of European Russia (Tver, Murom, and Kursk) exhibited similarities with populations from central–eastern Europe, and were distant from Russian sample from the northern Russia (Mezen district, Archangelsk region). Komi samples, especially Izhemski Komi, were significantly different from all other populations studied. These can be considered as a second pole of genetic diversity in northern Europe (in addition to the pole, occupied by Finns), as they had a distinct ancestry component. Russians from Mezen and the Finnic-speaking Veps were positioned between the two poles, but differed from each other in the proportions of Komi and Finnic ancestries. In general, our data provides a more complete genetic map of Europe accounting for the diversity in its most eastern (northeastern) populations.

A New HLA Map of Europe: Regional Genetic Variation and Its Implication for Peopling History, Disease-Association Studies and Tissue Transplantation

Objectives: HLA genes are highly polymorphic in human populations as a result of diversifying selection related to their immune function. However, HLA geographic variation worldwide suggests that demographic factors also shaped their evolution. We here analyzed in detail HLA genetic variation in Europe in order to identify signatures of migration history and/or natural selection. Methods: Relationships between HLA diversity and geography were analyzed at 7 loci through several approaches including linear regression on gene diversity and haplotype frequencies. Regional variation was also assessed on HLA multi-locus phenotypes through structure analysis. Deviation from neutrality was tested by resampling. Results: Geographic distance was a strong predictor of HLA variation at 5 loci (A, B, C, DRB1 and DPB1) in Europe, and latitude significantly shaped HLA gene diversity and haplotype frequencies. Whereas the main level of genetic diversity was found within populations, both HLA gene frequencies and phenotypic profiles revealed regional variation, Southeast Europe, Great Britain and Finland being the most distinctive. Effects of natural selection were suggested at the DQ loci. Conclusions: HLA regional variation was observed in Europe and can be related to population history, locus HLA-A providing by far the strongest signals. This new HLA map of Europe represents an invaluable reference for disease-association studies and tissue transplantation.

European Genetic Diversity through Space and Time

sions are nevertheless to be confirmed through further studies, as they are challenged in the next two papers by Barbujani (University of Ferrara, Italy) and Currat and Silva (University of Geneva, Switzerland), respectively. Barbujani’s favoured interpretation of the current European genetic variation is a genetic signature of a Neolithic demic diffusion process, as evidence of a Palaeolithic legacy is seriously lacking, he thinks. However, this author agrees that both a model of genealogical continuity since the Palaeolithic and a model of radical demographic replacement in Neolithic times are too simplistic to explain the current observations and should probably be combined into a mixed scenario taking different factors into account like geographic heterogeneity and cultural shifts. Currat and Silva’s claims are more extreme as, for these authors, a great part of the current European diversity clearly traces back to pre-Neolithic times. By reviewing several publications using a spatially explicit simulation framework, they explain how clinal genetic patterns may result from various phenomena, including allele surfing, which could have occurred at different prehistoric periods, were they Neolithic, Mesolithic or Palaeolithic. To reach some consensual scenario between different scholars, the authors underline the need to integrate both ancient and modern DNA data in spatial simulation approaches. This special issue of Human Heredity has been stimulated by a scientific meeting held in Geneva, Switzerland, in January 2013 as the closing conference of a European COST Action (BM0803), also supported by the Swiss National Science Foundation. The main objective of the conference was to round up our knowledge on the genetic diversity and origins of European populations, by taking into account both ancient and modern molecular data and sophisticated data analyses and computer simulation methods that have been developed in the last few decades within the frame of population genetics. As suggested by the subtitle of this issue, the questions we address(ed) are related both to the demographic history of European populations, a subject still at the centre of a heated scientific debate, and to the clinical consequences and implications of such a history, in terms of risk factors in both natural and clinical contexts. To start with, Deguilloux and Mendisco (University of Bordeaux 1, France) illustrate the state of the art of Paleogenetic studies in Europe, underlining the potentials of ancient DNA for reconstructing the European past, but also its limitations due to often poor and heterogeneous sampling. A striking observation done by these authors is the genetic discontinuity between ancient and extant European populations, suggesting population replacements not only between the Paleolithic and Neolithic periods, but also between the Neolithic and today. These concluPublished online: May 21, 2014

Genetic characterization of northeastern Italian population isolates in the context of broader European genetic diversity

Population genetic studies on European populations have highlighted Italy as one of genetically most diverse regions. This is possibly due to the country's complex demographic history and large variability in terrain throughout the territory. This is the reason why Italy is enriched for population isolates, Sardinia being the best-known example. As the population isolates have a great potential in disease-causing genetic variants identification, we aimed to genetically characterize a region from northeastern Italy, which is known for isolated communities. Total of 1310 samples, collected from six geographically isolated villages, were genotyped at >145 000 single-nucleotide polymorphism positions. Newly genotyped data were analyzed jointly with the available genome-wide data sets of individuals of European descent, including several population isolates. Despite the linguistic differences and geographical isolation the village populations still show the greatest genetic similarity to other Italian samples. The genetic isolation and small effective population size of the village populations is manifested by higher levels of genomic homozygosity and elevated linkage disequilibrium. These estimates become even more striking when the detected substructure is taken into account. The observed level of genetic isolation in Friuli-Venezia Giulia region is more extreme according to several measures of isolation compared with Sardinians, French Basques and northern Finns, thus proving the status of an isolate.

Commentary on Sokal, Oden, and Thomson's “A Problem with Synthetic Maps” (1999)

The demographic impact of the origin of agriculture in Europe has been a long-standing area of interest and controversy in human genetics. For contemporary students of human population genetics, reviewing past work on this question can serve as a wonderful case study that illuminates different approaches that one can take to study historical processes by using genetics and can highlight the inherent challenges. One chapter in that history involves Robert Sokal’s contributions, including his critique of synthetic maps. Robert Sokal became keenly interested in this question, as well as other potential factors structuring genetic diversity in Europe, and he worked with great rigor and insight. His work spanned genetics (e.g., Sokal et al. 1991), linguistics (e.g., Sokal et al. 1990), and also included the analysis of a large-scale ethnohistorical database that he created (e.g., Sokal et al. 1991). Whereas most of his work on European human genetic diversity took place in the late 1980s and early 1990s, in 1999 he published a short piece in Human Biology revisiting and critiquing the analysis of synthetic maps (maps based on principal components analysis, PCA) that Cavalli-Sforza and his colleagues started using in the late 1970s (Cavalli-Sforza et al. 1994; Menozzi et al. 1978; Piazza et al. 1991). This made for a lively exchange in the pages of Human Biology. The original piece (Sokal et al. 1999a) was published with a response from Cavalli-Sforza’s group (Rendine et al. 1999), and later in the same year Sokal published a letter critiquing the Rendine et al. (1999) response (Sokal et al. 1999b). Previous to the 1999 exchange, both Sokal and Cavalli-Sforza’s groups had, in separate papers, agreed that population genetic data from Europe support the existence of clinal patterns in allele frequencies that align with the expansion of agriculture, and that such clinal patterns support the demic diffusion hypothesis. Cavalli-Sforza’s group argued this point most strongly by using synthetic maps, showing that in their data the PC1 map in Europe has a northwest/southeast gradient that mirrors the expansion of agriculture (e.g., Menozzi et al. 1978). In contrast, Sokal’s group used an analysis based on distance metrics (Sokal et al. 1991). Specifically, they assessed how genetic distances correlate with the timing of the origin-of-agriculture and found a correlation, even after accounting for the partial correlation due to geographic distance. So, whereas both groups

Commentary on Sokal, Oden, and Thomson's "A Problem with Synthetic Maps" (1999)

Commentary on Sokal, Oden, and Thomson's "A Problem with Synthetic Maps" (1999) John Novembre Correction: Due to an error at the printer, the original article page range (620–623) was incorrect. The correct pagination is 623–626 and is reflected in this updated article. Click here for the corrected PDF. The demographic impact of the origin of agriculture in Europe has been a long-standing area of interest and controversy in human genetics. For contemporary students of human population genetics, reviewing past work on this question can serve as a wonderful case study that illuminates different approaches that one can take to study historical processes by using genetics and can highlight the inherent challenges. One chapter in that history involves Robert Sokal's contributions, including his critique of synthetic maps. Robert Sokal became keenly interested in this question, as well as other potential factors structuring genetic diversity in Europe, and he worked with great rigor and insight. His work spanned genetics (e.g., Sokal et al. 1991), linguistics (e.g., Sokal et al. 1990), and also included the analysis of a large-scale ethnohistorical database that he created (e.g., Sokal et al. 1991). Whereas most of his work on European human genetic diversity took place in the late 1980s and early 1990s, in 1999 he published a short piece in Human Biology revisiting and critiquing the analysis of synthetic maps (maps based on principal components analysis, PCA) that Cavalli-Sforza and his colleagues started using in the late 1970s (Cavalli-Sforza et al. 1994; Menozzi et al. 1978; Piazza et al. 1991). This made for a lively exchange in the pages of Human Biology. The original piece (Sokal et al. 1999a) was published with a response from Cavalli-Sforza's group (Rendine et al. 1999), and later in the same year Sokal published a letter critiquing the Rendine et al. (1999) response (Sokal et al. 1999b). Previous to the 1999 exchange, both Sokal and Cavalli-Sforza's groups had, in separate papers, agreed that population genetic data from Europe support the existence of clinal patterns in allele frequencies that align with the expansion of agriculture, and that such clinal patterns support the demic diffusion hypothesis. Cavalli-Sforza's group argued this point most strongly by using synthetic maps, showing that in their data the PC1 map in Europe has a northwest/southeast gradient that mirrors the expansion of agriculture (e.g., Menozzi et al. 1978). In contrast, Sokal's group used an analysis based on distance metrics (Sokal et al. 1991). Specifically, they assessed how genetic distances correlate with the timing of the origin-of-agriculture and found a correlation, even after accounting for the partial correlation due to geographic distance. So, whereas both groups [End Page 623] ultimately were in agreement about their conclusions regarding clines, they differed in how they reached those conclusions. In Sokal et al.'s 1999 critique of synthetic maps, the focus is on a more general problem in population genetic studies: the incompleteness of most samples. For logistical reasons, it is challenging to get a perfectly uniform sampling over the study area. The dataset that both Sokal and Cavalli-Sforza's group analyzed had sampling locales that were geographically clustered and intervening areas that went unsampled. As Sokal highlighted, Cavalli-Sforza's team dealt with the incomplete data by spatially interpolating the observed allele frequencies along a complete grid across Europe and then running the PCA to produce the synthetic map. This approach falls into a category sometimes referred to by statisticians as using "pseudodata"—where some initial data are used to infer an intermediate variable, and then analysis is run on those intermediate values. The intermediate variables are pseudodata in the sense that they are treated as real data when they are not directly observed. The problem of taking such an approach in a spatial context is not simply that the underlying uncertainty in downstream inferences may be underrepresented. As Sokal and colleagues made clear in their paper, spatial interpolation may falsely create autocorrelation in the data, and, "The extra spatial autocorrelation falsely enhances or distorts true trends in such data." To quantify the effect, they conducted numerical experiments with data...

DNase SISPA-Next Generation Sequencing Confirms Schmallenberg Virus in Belgian Field Samples and Identifies Genetic Variation in Europe

In 2011, a novel Orthobunyavirus was identified in cattle and sheep in Germany and the Netherlands. This virus was named Schmallenberg virus (SBV). Later, presence of the virus was confirmed using real time RT-PCR in cases of congenital malformations of bovines and ovines in several European countries, including Belgium. In the absence of specific sequencing protocols for this novel virus we confirmed its presence in RT-qPCR positive field samples using DNase SISPA-next generation sequencing (NGS), a virus discovery method based on random amplification and next generation sequencing. An in vitro transcribed RNA was used to construct a standard curve allowing the quantification of viral RNA in the field samples. Two field samples of aborted lambs containing 7.66 and 7.64 log10 RNA copies per µL total RNA allowed unambiguous identification of SBV. One sample yielded 192 SBV reads covering about 81% of the L segment, 56% of the M segment and 13% of the S segment. The other sample resulted in 8 reads distributed over the L and M segments. Three weak positive field samples (one from an aborted calf, two from aborted lambs) containing virus quantities equivalent to 4.27–4.89 log10 RNA copies per µL did not allow identification using DNase SISPA-NGS. This partial sequence information was compared to the whole genome sequence of SBV isolated from bovines in Germany, identifying several sequence differences. The applied viral discovery method allowed the confirmation of SBV in RT-qPCR positive brain samples. However, the failure to confirm SBV in weak PCR-positive samples illustrates the importance of the selection of properly targeted and fresh field samples in any virus discovery method. The partial sequences derived from the field samples showed several differences compared to the sequences from bovines in Germany, indicating sequence divergence within the epidemic.

Diverse spore rains and limited local exchange shape fern genetic diversity in a recently created habitat colonized by long-distance dispersal

Populations established by long-distance colonization are expected to show low levels of genetic variation per population, but strong genetic differentiation among populations. Whether isolated populations indeed show this genetic signature of isolation depends on the amount and diversity of diaspores arriving by long-distance dispersal, and time since colonization. For ferns, however, reliable estimates of long-distance dispersal rates remain largely unknown, and previous studies on fern population genetics often sampled older or non-isolated populations. Young populations in recent, disjunct habitats form a useful study system to improve our understanding of the genetic impact of long-distance dispersal. Microsatellite markers were used to analyse the amount and distribution of genetic diversity in young populations of four widespread calcicole ferns (Asplenium scolopendrium, diploid; Asplenium trichomanes subsp. quadrivalens, tetraploid; Polystichum setiferum, diploid; and Polystichum aculeatum, tetraploid), which are rare in The Netherlands but established multiple populations in a forest (the Kuinderbos) on recently reclaimed Dutch polder land following long-distance dispersal. Reference samples from populations throughout Europe were used to assess how much of the existing variation was already present in the Kuinderbos. A large part of the Dutch and European genetic diversity in all four species was already found in the Kuinderbos. This diversity was strongly partitioned among populations. Most populations showed low genetic variation and high inbreeding coefficients, and were assigned to single, unique gene pools in cluster analyses. Evidence for interpopulational gene flow was low, except for the most abundant species. The results show that all four species, diploids as well as polyploids, were capable of frequent long-distance colonization via single-spore establishment. This indicates that even isolated habitats receive dense and diverse spore rains, including genotypes capable of self-fertilization. Limited gene flow may conserve the genetic signature of multiple long-distance colonization events for several decades.

A Time Series of Prehistoric Mitochondrial DNA Reveals Western European Genetic Diversity Was Largely Established by the Bronze Age

A major unanswered question concerns the roles of continuity versus change in prehistoric Europe. For the first time, genetic samples of reasonable size taken at multiple time points are revealing piecemeal snapshots of European prehistory at different dates and places across the continent. Here, we pull these disparate datasets together to illustrate how human genetic variation has changed spatially and temporally in Europe from the Mesolithic through to the present day. Mitochondrial DNA (mtDNA) haplogroups were determined for 532 European individuals from four major eras: the Mesolithic, Neolithic, Chalcolithic (late Neolithic/early Bronze Age transition) and Modern periods. The Mesolithic was characterized by low mtDNA diversity. These initial European settler haplogroups declined rapidly in the Neolithic, as farmers from the east introduced a new suite of mtDNA lineages into Western Europe. For the first time, we show that the Chalcolithic was also a time of substantial genetic change in Europe. However, rather than the arrival of new mtDNA lineages, this period was characterized by major fluctuations in the frequencies of existing haplogroups. Besides the expansion of haplogroup H, there were few major changes in mtDNA diversity from the Chalcolithic to modern times, thus suggesting that the basic profile of mod- ern western European mtDNA diversity was largely established by the Bronze Age.

Genetic variation in the Sorbs of eastern Germany in the context of broader European genetic diversity

Population isolates have long been of interest to genetic epidemiologists because of their potential to increase power to detect disease-causing genetic variants. The Sorbs of Germany are considered as cultural and linguistic isolates and have recently been the focus of disease association mapping efforts. They are thought to have settled in their present location in eastern Germany after a westward migration from a largely Slavic-speaking territory during the Middle Ages. To examine Sorbian genetic diversity within the context of other European populations, we analyzed genotype data for over 30 000 autosomal single-nucleotide polymorphisms from over 200 Sorbs individuals. We compare the Sorbs with other European individuals, including samples from population isolates. Despite their geographical proximity to German speakers, the Sorbs showed greatest genetic similarity to Polish and Czech individuals, consistent with the linguistic proximity of Sorbian to other West Slavic languages. The Sorbs also showed evidence of subtle levels of genetic isolation in comparison with samples from non-isolated European populations. The level of genetic isolation was less than that observed for the Sardinians and French Basque, who were clear outliers on multiple measures of isolation. The finding of the Sorbs as only a minor genetic isolate demonstrates the need to genetically characterize putative population isolates, as they possess a wide range of levels of isolation because of their different demographic histories.

European Domestic Horses Originated in Two Holocene Refugia

The role of European wild horses in horse domestication is poorly understood. While the fossil record for wild horses in Europe prior to horse domestication is scarce, there have been suggestions that wild populations from various European regions might have contributed to the gene pool of domestic horses. To distinguish between regions where domestic populations are mainly descended from local wild stock and those where horses were largely imported, we investigated patterns of genetic diversity in 24 European horse breeds typed at 12 microsatellite loci. The distribution of high levels of genetic diversity in Europe coincides with the distribution of predominantly open landscapes prior to domestication, as suggested by simulation-based vegetation reconstructions, with breeds from Iberia and the Caspian Sea region having significantly higher genetic diversity than breeds from central Europe and the UK, which were largely forested at the time the first domestic horses appear there. Our results suggest that not only the Eastern steppes, but also the Iberian Peninsula provided refugia for wild horses in the Holocene, and that the genetic contribution of these wild populations to local domestic stock may have been considerable. In contrast, the consistently low levels of diversity in central Europe and the UK suggest that domestic horses in these regions largely derive from horses that were imported from the Eastern refugium, the Iberian refugium, or both.

Nuclear and chloroplast microsatellites show multiple introductions in the worldwide invasion history of common ragweed, Ambrosia artemisiifolia.

Background Ambrosia artemisiifolia is a North American native that has become one of the most problematic invasive plants in Europe and Asia. We studied its worldwide population genetic structure, using both nuclear and chloroplast microsatellite markers and an unprecedented large population sampling. Our goals were (i) to identify the sources of the invasive populations; (ii) to assess whether all invasive populations were founded by multiple introductions, as previously found in France; (iii) to examine how the introductions have affected the amount and structure of genetic variation in Europe; (iv) to document how the colonization of Europe proceeded; (v) to check whether populations exhibit significant heterozygote deficiencies, as previously observed.Principal FindingsWe found evidence for multiple introductions of A. artemisiifolia, within regions but also within populations in most parts of its invasive range, leading to high levels of diversity. In Europe, introductions probably stem from two different regions of the native area: populations established in Central Europe appear to have originated from eastern North America, and Eastern European populations from more western North America. This may result from differential commercial exchanges between these geographic regions. Our results indicate that the expansion in Europe mostly occurred through long-distance dispersal, explaining the absence of isolation by distance and the weak influence of geography on the genetic structure in this area in contrast to the native range. Last, we detected significant heterozygote deficiencies in most populations. This may be explained by partial selfing, biparental inbreeding and/or a Wahlund effect and further investigation is warranted.ConclusionsThis insight into the sources and pathways of common ragweed expansion may help to better understand its invasion success and provides baseline data for future studies on the evolutionary processes involved during range expansion in novel environments.

The value of genetic resources in agriculture: a meta-analysis assessing existing knowledge and future research needs

The protection of genetic resources in agriculture is an important aspect of biodiversity conservation. Knowledge of the value of genetic resources can contribute to determining the appropriate focus and extent of conservation. This study reviewed and summarised literature on the economic value of genetic resources using meta-analysis. Altogether, 22 studies were used to describe current knowledge on the value of genetic resources. Furthermore, 14 studies with 93 value observations were examined with a meta-regression model to identify variables that explain the willingness-to-pay (WTP) for or willingness-to-accept (WTA) loss of genetic resources. Grain genetic resources were ascribed lower value compared to animal genetic resources (AnGR) and agrobiodiversity, and the values of breeds or varieties and conservation programmes were higher than the value of individual attributes. Future research should address the gaps in knowledge that are relevant for policy-making. This particularly includes improving knowledge on the value of plant genetic resources (PGR), obtaining value estimates for maintaining genetic diversity in Europe and the United States, estimating the relative magnitude of use and non-use values and determining the value consumers place on genetic resources and diversity in agriculture. An extensive database with valuation literature on genetic resources that fulfils the requirements for benefit transfer is essential to utilise value information more efficiently in decision-making situations.

Mixed mating system in the fern Asplenium scolopendrium: implications for colonization potential

Human-mediated environmental change is increasing selection pressure for the capacity in plants to colonize new areas. Habitat fragmentation combined with climate change, in general, forces species to colonize areas over longer distances. Mating systems and genetic load are important determinants of the establishment and long-term survival of new populations. Here, the mating system of Asplenium scolopendrium, a diploid homosporous fern species, is examined in relation to colonization processes. A common environment experiment was conducted with 13 pairs of sporophytes, each from a different site. Together they constitute at least nine distinct genotypes, representing an estimated approx. 95 % of the non-private intraspecific genetic variation in Europe. Sporophyte production was recorded for gametophytes derived from each parent sporophyte. Gametophytes were grown in vitro in three different ways: (I) in isolation, (II) with a gametophyte from a different sporophyte within the same site or (III) with a partner from a different site. Sporophyte production was highest in among-site crosses (III), intermediate in within-site crosses (II) and was lowest in isolated gametophytes (I), strongly indicating inbreeding depression. However, intragametophytic selfing was observed in most of the genotypes tested (eight out of nine). The results imply a mixed mating system in A. scolopendrium, with outcrossing when possible and occasional selfing when needed. Occasional intragametophytic selfing facilitates the successful colonization of new sites from a single spore. The resulting sporophyte, which will be completely homozygous, will shed large amounts of spores over time. Each year this creates a bed of gametophytes in the vicinity of the parent. Any unrelated spore which arrives is then selectively favoured to reproduce and contribute its genes to the new population. Thus, while selfing facilitates initial colonization success, inbreeding depression promotes genetically diverse populations through outcrossing. The results provide further evidence against the overly simple dichotomous distinction of fern species as either selfing or outcrossing.

Update to Chikhi et al.'s “Clinal Variation in the Nuclear DNA of Europeans” (1998): Genetic Data and Storytelling—From Archaeogenetics to Astrologenetics?

When Clinal Variation in the Nuclear of Europeans was published in 1998, its message was relatively simple and pretty clear from its title. First, we were using genetic data from present- day European populations to describe how this diversity was distributed, by way of spatial autocorrelation analysis. Second, we observed clear clinal patterns in most genetic markers; that is, we found that autocorrelation was positive and significant at short distances and negative and significant at larger distances. Third, the difference from previous studies was that the markers we used were directly based on information. Sure enough there had been studies de - scribing the spatial patterns of genetic diversity in Europe, but they were based on so- called classical markers (allozymes and blood groups). At the time the only studies using proper DNA were those based on mitochondrial DNA. Looking back, our paper came, to a large extent by chance, at an interesting moment. Indeed, for the last two decades studies by Cavalli- Sforza, Sokal, Barbu-

Human mitochondrial DNA variation in Southern Italy

Background: Since prehistoric times Southern Italy has been a cultural crossroads of the Mediterranean basin. Genetic data on the peoples of Basilicata and Calabria are scarce and, particularly, no records on mtDNA variability have been published.Aim: In this study mtDNA haplotypes of populations from Basilicata, Calabria and Sicily are compared with those of other Italian and Mediterranean populations, so as to investigate their genetic relationships.Subjects and methods: A total of 341 individuals was analysed for mtDNA in order to provide their classification into haplogroups. Multivariate analysis was used to compare the studied populations with other Mediterranean samples; median-joining network analysis was applied to observe the relationship between the major lineages of the Southern Italians.Results: The haplogroup distribution in the Southern Italian samples falls within the typical pattern of mtDNA variability of Western Eurasia. The comparison with other Mediterranean countries showed a substantial homogeneity of the area, which is probably related to the historic contact through the Mediterranean Sea.Conclusion: The mtDNA analysis demonstrated that Southern Italy displays a typical pattern of Mediterranean basin variability, even though it appears plausible that Southern Italy was less affected by the effects of the Late Glacial Maximum, which reduced genetic diversity in Europe.