Independent histories of human Y chromosomes from Melanesia and Australia

Episodes of diversification and isolation in Island Southeast Asian and Near Oceanian male lineages

Island Southeast Asia (ISEA) and Oceania host one of the world’s richest assemblages of human phenotypic, linguistic, and cultural diversity. Despite this, the region’s male genetic lineages are globally among the last to remain unresolved. We compiled ∼9.7 Mb of Y chromosome (chrY) sequence from a diverse sample of over 380 men from this region, including 152 first reported here. The granularity of this data set allows us to fully resolve and date the regional chrY phylogeny. This new high-resolution tree confirms two main population bursts: multiple rapid diversifications following the region’s initial settlement ∼50 kya, and extensive expansions <6 kya. Notably, ∼40–25 kya the deep rooting local lineages of C-M130, M-P256, and S-B254 show almost no further branching events in ISEA, New Guinea, and Australia, matching a similar pause in diversification seen in maternal mitochondrial DNA lineages. The main local lineages start diversifying ∼25 kya, at the time of the last glacial maximum. This improved chrY topology highlights localized events with important historical implications, including pre-Holocene contact between Mainland and ISEA, potential interactions between Australia and the Papuan world, and a sustained period of diversification following the flooding of the ancient Sunda and Sahul continents as the insular landscape observed today formed. The high-resolution phylogeny of the chrY presented here thus enables a detailed exploration of past isolation, interaction, and change in one of the world’s least understood regions.

Elucidating biogeographical patterns in Australian native canids using genome wide SNPs

Dingoes play a strong role in Australia's ecological framework as the apex predator but are under threat from hybridization and agricultural control programs. Government legislation lists the conservation of the dingo as an important aim, yet little is known about the biogeography of this enigmatic canine, making conservation difficult. Mitochondrial and Y chromosome DNA studies show evidence of population structure within the dingo. Here, we present the data from Illumina HD canine chip genotyping for 23 dingoes from five regional populations, and five New Guinea Singing Dogs to further explore patterns of biogeography using genome-wide data. Whole genome single nucleotide polymorphism (SNP) data supported the presence of three distinct dingo populations (or ESUs) subject to geographical subdivision: southeastern (SE), Fraser Island (FI) and northwestern (NW). These ESUs should be managed discretely. The FI dingoes are a known reservoir of pure, genetically distinct dingoes. Elevated inbreeding coefficients identified here suggest this population may be genetically compromised and in need of rescue; current lethal management strategies that do not consider genetic information should be suspended until further data can be gathered. D statistics identify evidence of historical admixture or ancestry sharing between southeastern dingoes and South East Asian village dogs. Conservation efforts on mainland Australia should focus on the SE dingo population that is under pressure from domestic dog hybridization and high levels of lethal control. Further data concerning the genetic health, demographics and prevalence of hybridization in the SE and FI dingo populations is urgently needed to develop evidence based conservation and management strategies.

A phylogenetic framework facilitates Y-STR variant discovery and classification via massively parallel sequencing

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23 Y-chromosomal STRs (PPY23) reanalysed by massively parallel sequencing.

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Phylogeny-based approach captures wide range of sequence variants in 100 samples.

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STR variants described in phase with their flanking sequences.

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Phylogenetic framework clarifies allele nomenclature and mutation processes.

Short tandem repeats on the male-specific region of the Y chromosome (Y-STRs) are permanently linked as haplotypes, and therefore Y-STR sequence diversity can be considered within the robust framework of a phylogeny of haplogroups defined by single nucleotide polymorphisms (SNPs). Here we use massively parallel sequencing (MPS) to analyse the 23 Y-STRs in Promega’s prototype PowerSeq™ Auto/Mito/Y System kit (containing the markers of the PowerPlex® Y23 [PPY23] System) in a set of 100 diverse Y chromosomes whose phylogenetic relationships are known from previous megabase-scale resequencing. Including allele duplications and alleles resulting from likely somatic mutation, we characterised 2311 alleles, demonstrating 99.83% concordance with capillary electrophoresis (CE) data on the same sample set. The set contains 267 distinct sequence-based alleles (an increase of 58% compared to the 169 detectable by CE), including 60 novel Y-STR variants phased with their flanking sequences which have not been reported previously to our knowledge. Variation includes 46 distinct alleles containing non-reference variants of SNPs/indels in both repeat and flanking regions, and 145 distinct alleles containing repeat pattern variants (RPV). For DYS385a,b, DYS481 and DYS390 we observed repeat count variation in short flanking segments previously considered invariable, and suggest new MPS-based structural designations based on these. We considered the observed variation in the context of the Y phylogeny: several specific haplogroup associations were observed for SNPs and indels, reflecting the low mutation rates of such variant types; however, RPVs showed less phylogenetic coherence and more recurrence, reflecting their relatively high mutation rates. In conclusion, our study reveals considerable additional diversity at the Y-STRs of the PPY23 set via MPS analysis, demonstrates high concordance with CE data, facilitates nomenclature standardisation, and places Y-STR sequence variants in their phylogenetic context.

The origin and expansion of Pama-Nyungan languages across Australia

It remains a mystery how Pama-Nyungan, the world's largest hunter-gatherer language family, came to dominate the Australian continent. Some argue that social or technological advantages allowed rapid language replacement from the Gulf Plains region during the mid-Holocene. Others have proposed expansions from refugia linked to climatic changes after the last ice age or, more controversially, during the initial colonization of Australia. Here, we combine basic vocabulary data from 306 Pama-Nyungan languages with Bayesian phylogeographic methods to explicitly model the expansion of the family across Australia and test between these origin scenarios. We find strong and robust support for a Pama-Nyungan origin in the Gulf Plains region during the mid-Holocene, implying rapid replacement of non-Pama-Nyungan languages. Concomitant changes in the archaeological record, together with a lack of strong genetic evidence for Holocene population expansion, suggests that Pama-Nyungan languages were carried as part of an expanding package of cultural innovations that probably facilitated the absorption and assimilation of existing hunter-gatherer groups.

Carriers of mitochondrial DNA macrohaplogroup R colonized Eurasia and Australasia from a southeast Asia core area

BACKGROUND

The colonization of Eurasia and Australasia by African modern humans has been explained, nearly unanimously, as the result of a quick southern coastal dispersal route through the Arabian Peninsula, the Indian subcontinent, and the Indochinese Peninsula, to reach Australia around 50 kya. The phylogeny and phylogeography of the major mitochondrial DNA Eurasian haplogroups M and N have played the main role in giving molecular genetics support to that scenario. However, using the same molecular tools, a northern route across central Asia has been invoked as an alternative that is more conciliatory with the fossil record of East Asia. Here, we assess as the Eurasian macrohaplogroup R fits in the northern path.

RESULTS

Haplogroup U, with a founder age around 50 kya, is one of the oldest clades of macrohaplogroup R in western Asia. The main branches of U expanded in successive waves across West, Central and South Asia before the Last Glacial Maximum. All these dispersions had rather overlapping ranges. Some of them, as those of U6 and U3, reached North Africa. At the other end of Asia, in Wallacea, another branch of macrohaplogroup R, haplogroup P, also independently expanded in the area around 52 kya, in this case as isolated bursts geographically well structured, with autochthonous branches in Australia, New Guinea, and the Philippines.

CONCLUSIONS

Coeval independently dispersals around 50 kya of the West Asia haplogroup U and the Wallacea haplogroup P, points to a halfway core area in southeast Asia as the most probable centre of expansion of macrohaplogroup R, what fits in the phylogeographic pattern of its ancestor, macrohaplogroup N, for which a northern route and a southeast Asian origin has been already proposed.

Aboriginal Australian mitochondrial genome variation - an increased understanding of population antiquity and diversity

Aboriginal Australians represent one of the oldest continuous cultures outside Africa, with evidence indicating that their ancestors arrived in the ancient landmass of Sahul (present-day New Guinea and Australia) ~55 thousand years ago. Genetic studies, though limited, have demonstrated both the uniqueness and antiquity of Aboriginal Australian genomes. We have further resolved known Aboriginal Australian mitochondrial haplogroups and discovered novel indigenous lineages by sequencing the mitogenomes of 127 contemporary Aboriginal Australians. In particular, the more common haplogroups observed in our dataset included M42a, M42c, S, P5 and P12, followed by rarer haplogroups M15, M16, N13, O, P3, P6 and P8. We propose some major phylogenetic rearrangements, such as in haplogroup P where we delinked P4a and P4b and redefined them as P4 (New Guinean) and P11 (Australian), respectively. Haplogroup P2b was identified as a novel clade potentially restricted to Torres Strait Islanders. Nearly all Aboriginal Australian mitochondrial haplogroups detected appear to be ancient, with no evidence of later introgression during the Holocene. Our findings greatly increase knowledge about the geographic distribution and phylogenetic structure of mitochondrial lineages that have survived in contemporary descendants of Australia’s first settlers.

Lack of gene-language correlation due to reciprocal female but directional male admixture in Austronesians and non-Austronesians of East Timor

Nusa Tenggara, including East Timor, located at the crossroad between Island Southeast Asia, Near Oceania, and Australia, are characterized by a complex cultural structure harbouring speakers from two different major linguistic groups of different geographic origins (Austronesian (AN) and non-Austronesian (NAN)). This provides suitable possibilities to study gene-language relationship; however, previous studies from other parts of Nusa Tenggara reported conflicting evidence about gene-language correlation in this region. Aiming to investigate gene-language relationships including sex-mediated aspects in East Timor, we analysed the paternally inherited non-recombining part of the Y chromosome (NRY) and the maternally inherited mitochondrial (mt) DNA in a representative collection of AN- and NAN-speaking groups. Y-SNP (single-nucleotide polymorphism) data were newly generated for 273 samples and combined with previously established Y-STR (short tandem repeat) data of the same samples, and with previously established mtDNA data of 290 different samples with, however, very similar representation of geographic and linguistic coverage of the country. We found NRY and mtDNA haplogroups of previously described putative East/Southeast Asian (E/SEA) and Near Oceanian (NO) origins in both AN and NAN speakers of East Timor, albeit in different proportions, suggesting reciprocal genetic admixture between both linguistic groups for females, but directional admixture for males. Our data underline the dual genetic origin of East Timorese in E/SEA and NO, and highlight that substantial genetic admixture between the two major linguistic groups had occurred, more so via women than men. Our study therefore provides another example where languages and genes do not conform due to sex-biased genetic admixture across major linguistic groups.

Mitochondrial DNA diversity of present-day Aboriginal Australians and implications for human evolution in Oceania

Aboriginal Australians are one of the more poorly studied populations from the standpoint of human evolution and genetic diversity. Thus, to investigate their genetic diversity, the possible date of their ancestors' arrival and their relationships with neighboring populations, we analyzed mitochondrial DNA (mtDNA) diversity in a large sample of Aboriginal Australians. Selected mtDNA single-nucleotide polymorphisms and the hypervariable segment haplotypes were analyzed in 594 Aboriginal Australians drawn from locations across the continent, chiefly from regions not previously sampled. Most (~78%) samples could be assigned to mtDNA haplogroups indigenous to Australia. The indigenous haplogroups were all ancient (with estimated ages >40 000 years) and geographically widespread across the continent. The most common haplogroup was P (44%) followed by S (23%) and M42a (9%). There was some geographic structure at the haplotype level. The estimated ages of the indigenous haplogroups range from 39 000 to 55 000 years, dates that fit well with the estimated date of colonization of Australia based on archeological evidence (~47 000 years ago). The distribution of mtDNA haplogroups in Australia and New Guinea supports the hypothesis that the ancestors of Aboriginal Australians entered Sahul through at least two entry points. The mtDNA data give no support to the hypothesis of secondary gene flow into Australia during the Holocene, but instead suggest long-term isolation of the continent.

Ancestry of the Timorese: age-related macular degeneration associated genotype and allele sharing among human populations from throughout the world

We observed that the third leading cause of blindness in the world, age-related macular degeneration (AMD), occurs at a very low documented frequency in a population-based cohort from Timor-Leste. Thus, we determined a complete catalog of the ancestry of the Timorese by analysis of whole exome chip data and haplogroup analysis of SNP genotypes determined by sequencing the Hypervariable I and II regions of the mitochondrial genome and 17 genotyped YSTR markers obtained from 535 individuals. We genotyped 20 previously reported AMD-associated SNPs in the Timorese to examine their allele frequencies compared to and between previously documented AMD cohorts of varying ethnicities. For those without AMD (average age > 55 years), genotype and allele frequencies were similar for most SNPs with a few exceptions. The major risk allele of HTRA1 rs11200638 (10q26) was at a significantly higher frequency in the Timorese, as well as 3 of the 5 protective CFH (1q32) SNPs (rs800292, rs2284664, and rs12066959). Additionally, the most commonly associated AMD-risk SNP, CFH rs1061170 (Y402H), was also seen at a much lower frequency in the Korean and Timorese populations than in the assessed Caucasian populations (C ~7 vs. ~40%, respectively). The difference in allele frequencies between the Timorese population and the other genotyped populations, along with the haplogroup analysis, also highlight the genetic diversity of the Timorese. Specifically, the most common ancestry groupings were Oceanic (Melanesian and Papuan) and Eastern Asian (specifically Han Chinese). The low prevalence of AMD in the Timorese population (2 of 535 randomly selected participants) may be due to the enrichment of protective alleles in this population at the 1q32 locus.

Genome-wide insights into the genetic history of human populations

Although mtDNA and the non-recombining Y chromosome (NRY) studies continue to provide valuable insights into the genetic history of human populations, recent technical, methodological and computational advances and the increasing availability of large-scale, genome-wide data from contemporary human populations around the world promise to reveal new aspects, resolve finer points, and provide a more detailed look at our past demographic history. Genome-wide data are particularly useful for inferring migrations, admixture, and fine structure, as well as for estimating population divergence and admixture times and fluctuations in effective population sizes. In this review, we highlight some of the stories that have emerged from the analyses of genome-wide SNP genotyping data concerning the human history of Southern Africa, India, Oceania, Island South East Asia, Europe and the Americas and comment on possible future study directions. We also discuss advantages and drawbacks of using SNP-arrays, with a particular focus on the ascertainment bias, and ways to circumvent it.

Inference of sex-specific expansion patterns in human populations from Y-chromosome polymorphism

Studying the current distribution of genetic diversity in humans has important implications for our understanding of the history of our species. We analyzed a set of linked STR and SNP loci from the paternally inherited Y chromosome to infer the past demography of 55 African and Eurasian populations, using both the parametric and nonparametric coalescent-based methods implemented in the BEAST application. We inferred expansion events in most sedentary farmer populations, while we found constant effective population sizes for both nomadic hunter-gatherers and seminomadic herders. Our results differed, on several aspects, from previous results on mtDNA and autosomal markers. First, we found more recent expansion patterns in Eurasia than in Africa. This discrepancy, substantially stronger than the ones found with the other kind of markers, may result from a lower effective population size for men, which might have made male-transmitted markers more sensitive to the out-of-Africa bottleneck. Second, we found expansion signals only for sedentary farmers but not for nomadic herders in Central Asia, while these signals were found for both kind of populations in this area when using mtDNA or autosomal markers. Expansion signals in this area may result from spatial expansion processes and may have been erased for the Y chromosome among the herders because of restricted male gene flow.

Isolation, contact and social behavior shaped genetic diversity in West Timor

Timor, an eastern Indonesian island linking mainland Asia with Australia and the Pacific world, had a complex history, including its role as a contact zone between two language families (Austronesian and Trans-New Guinean), as well as preserving elements of a rich Austronesian cultural heritage, such as matrilocal marriage practices. Using an array of biparental (autosomal and X-chromosome single-nucleotide polymorphisms) and uniparental markers (Y chromosome and mitochondrial DNA), we reconstruct a broad genetic profile of Timorese in the Belu regency of West Timor, including the traditional princedom of Wehali, focusing on the effects of cultural practices, such as language and social change, on patterns of genetic diversity. Sex-linked data highlight the different histories and social pressures experienced by women and men. Measures of diversity and population structure show that Timorese men had greater local mobility than women, as expected in matrilocal communities, where women remain in their natal village, whereas men move to the home village of their wife. Reaching further back in time, maternal loci (mitochondrial DNA and the X chromosome) are dominated by lineages with immigrant Asian origins, whereas paternal loci (Y chromosome) tend to exhibit lineages of the earliest settlers in the eastern Indonesian region. The dominance of Asian female lineages is especially apparent in the X chromosome compared with the autosomes, suggesting that women played a paramount role during and after the period of Asian immigration into Timor, perhaps driven by the matrilocal marriage practices of expanding Austronesian communities.

A high-coverage genome sequence from an archaic Denisovan individual

We present a DNA library preparation method that has allowed us to reconstruct a high-coverage (30×) genome sequence of a Denisovan, an extinct relative of Neandertals. The quality of this genome allows a direct estimation of Denisovan heterozygosity indicating that genetic diversity in these archaic hominins was extremely low. It also allows tentative dating of the specimen on the basis of "missing evolution" in its genome, detailed measurements of Denisovan and Neandertal admixture into present-day human populations, and the generation of a near-complete catalog of genetic changes that swept to high frequency in modern humans since their divergence from Denisovans.

Distinct distribution of killer-cell immunoglobulin-like receptor genes in the Mugil and Ilaita areas of Papua New Guinea

The frequency of the killer-cell immunoglobulin-like receptor (KIR) genes and transmembrane alleles of KIR2DL4 were studied in coastal (Mugil community) and inland (Ilaita community) communities in Papua New Guinea. Linkage disequilibria between KIR genes and between alleles of KIR2DL4 and the KIR genes were similar to those found in other populations suggesting conservation of the usual gene order in Papua New Guinean haplotypes. Significant differences in the frequency of KIR genes were found between the two populations despite being separated by only 300 km. Examples of individuals who lacked the KIR2DL4 gene and others whose KIR2DL4 allele appeared to have 11 adenines in the polyadenine tract in exon 6 were identified. A relatively low frequency of the KIR A haplotype was found in both populations and particularly in the inland community. The KIR gene frequencies were consistent with the inland Ilaita community being closely related to Australian Aborigines and southern Indians, whereas the KIR gene frequencies of the coastal Mugil community appeared to have been influenced either by recent or ancient admixture from populations with a higher frequency of the KIR A haplotype.

Haplotype analysis of the polymorphic 17 YSTR markers in Kerala nontribal populations

The origin of the Kerala non tribal population has been a matter of contention for centuries. While some claim that Negritos were the first inhabitants, some historians suggest a Dravidian origin for all Keralites. The aim of our study has been to provide sufficient scientific evidence based on Y chromosome short tandem repeat (Y STR) analysis for tracing the paternal lineage and also to create a database of the Y STR haplotype of the male population for future forensic analysis. Whole blood samples (n = 168) were collected from unrelated healthy men of the Kerala non-tribal population over a period of 2 years from October 2009. Genomic DNA was extracted by salting out method. All samples were genotyped for the 17 Y STR loci by the AmpFLSTR Y-filer PCR Amplification Kit. The haplotype and allele frequencies were determined by direct counting and analyzed using Arlequin 3.1 software, and molecular variance was calculated with the Y chromosome haplotype reference database online analysis tool, www.yhrd.org . Haplotype diversity was calculated using HaPYDive ( http://portugene.com/hapydive.html ). The majority of haplotypes were unique (149/168). The variant allele 17.1 was observed in DYS 385 loci in three samples. Fifteen samples (8.93%) showed the presence of alleles that are not within the established marker range denoted as outside marker range (OMR). The allele frequency of Kerala non tribal population ranged from 0.00003 to 0.5809. The most polymorphic single locus marker was DYS 458. The haplotype diversity value for Kerala non tribal population was 0.9978. The pairwise difference value ranged from 0.0531 to 0.0854 on comparison of the haplotypes of the Kerala non tribals with other Indian populations. The multi dimensional scaling plot depicted the proximity of Kerala non tribal population with Vasterbotten population (Swedish) and Paiwan, Patyal population of Taiwan, Thailand, and Zhuang population of China. The results of the study indicate towards a European paternal lineage in the non tribal Kerala population.

Y-short tandem repeat haplotype and paternal lineage of the Ezhava population of Kerala, south India

AIM

To analyze the haplotype of the Ezhava population of Kerala, south India, using 8 short tandem repeat (STR) loci on the Y chromosome and trace the paternal genetic lineage of the population.

METHODS

Whole blood samples (n=104) were collected from unrelated healthy men of the Ezhava population over a period of one year from October 2009. Genomic DNA was extracted by salting out method. All samples were genotyped for the 8 Y-STR loci by the AmpFiSTR Y-filer PCR Amplification Kit. The haplotype and allele frequencies were determined by direct counting and analyzed using Arlequin 3.1 software, and molecular variance was calculated with the Y-chromosome haplotype reference database online analysis tool, www.yhrd.org.

RESULTS

Among the 104 examined haplotypes, we found 98 unique ones. The average gene diversity was 0.669, with the highest diversity of 0.9462 observed for the biallelic Y-STR marker DYS 385. The allele frequency among DYS loci varied between 0.0096 and 0.75. Out of the 104 haplotypes, 10 were identical to the Jat Sikh population of Punjab, which is the greatest number among the Indian populations, and 4 to the Turkish population, which is the greatest number among the European populations. According to the allele frequency of Y-STR, the Ezhavas were genetically more similar to the Europeans (60%) than to the East Asians (40%).

CONCLUSION

The vast majority of haplotypes were observed only once, reflecting the enormous genetic heterogeneity of the Ezhavas. Based on the genotype, the Ezhavas showed more resemblance to Jat Sikh population of Punjab and the Turkish populations than to the East Asians, hence indicating a paternal lineage of European origin.

The Y-chromosome landscape of the Philippines: extensive heterogeneity and varying genetic affinities of Negrito and non-Negrito groups

The Philippines exhibits a rich diversity of people, languages, and culture, including so-called 'Negrito' groups that have for long fascinated anthropologists, yet little is known about their genetic diversity. We report here, a survey of Y-chromosome variation in 390 individuals from 16 Filipino ethnolinguistic groups, including six Negrito groups, from across the archipelago. We find extreme diversity in the Y-chromosome lineages of Filipino groups with heterogeneity seen in both Negrito and non-Negrito groups, which does not support a simple dichotomy of Filipino groups as Negrito vs non-Negrito. Filipino non-recombining region of the human Y chromosome lineages reflect a chronology that extends from after the initial colonization of the Asia-Pacific region, to the time frame of the Austronesian expansion. Filipino groups appear to have diverse genetic affinities with different populations in the Asia-Pacific region. In particular, some Negrito groups are associated with indigenous Australians, with a potential time for the association ranging from the initial colonization of the region to more recent (after colonization) times. Overall, our results indicate extensive heterogeneity contributing to a complex genetic history for Filipino groups, with varying roles for migrations from outside the Philippines, genetic drift, and admixture among neighboring groups.

Whole-genome genetic diversity in a sample of Australians with deep Aboriginal ancestry

Australia was probably settled soon after modern humans left Africa, but details of this ancient migration are not well understood. Debate centers on whether the Pleistocene Sahul continent (composed of New Guinea, Australia, and Tasmania) was first settled by a single wave followed by regional divergence into Aboriginal Australian and New Guinean populations (common origin) or whether different parts of the continent were initially populated independently. Australia has been the subject of relatively few DNA studies even though understanding regional variation in genomic structure and diversity will be important if disease-association mapping methods are to be successfully evaluated and applied across populations. We report on a genome-wide investigation of Australian Aboriginal SNP diversity in a sample of participants from the Riverine region. The phylogenetic relationship of these Aboriginal Australians to a range of other global populations demonstrates a deep common origin with Papuan New Guineans and Melanesians, with little evidence of substantial later migration until the very recent arrival of European colonists. The study provides valuable and robust insights into an early and important phase of human colonization of the globe. A broader survey of Australia, including diverse geographic sample populations, will be required to fully appreciate the continent's unique population history and consequent genetic heritage, as well as the importance of both to the understanding of health issues.

Genetic diversity on the Comoros Islands shows early seafaring as major determinant of human biocultural evolution in the Western Indian Ocean

The Comoros Islands are situated off the coast of East Africa, at the northern entrance of the channel of Mozambique. Contemporary Comoros society displays linguistic, cultural and religious features that are indicators of interactions between African, Middle Eastern and Southeast Asian (SEA) populations. Influences came from the north, brought by the Arab and Persian traders whose maritime routes extended to Madagascar by 700-900 AD. Influences also came from the Far East, with the long-distance colonisation by Austronesian seafarers that reached Madagascar 1500 years ago. Indeed, strong genetic evidence for a SEA, but not a Middle Eastern, contribution has been found on Madagascar, but no genetic trace of either migration has been shown to exist in mainland Africa. Studying genetic diversity on the Comoros Islands could therefore provide new insights into human movement in the Indian Ocean. Here, we describe Y chromosomal and mitochondrial genetic variation in 577 Comorian islanders. We have defined 28 Y chromosomal and 9 mitochondrial lineages. We show the Comoros population to be a genetic mosaic, the result of tripartite gene flow from Africa, the Middle East and Southeast Asia. A distinctive profile of African haplogroups, shared with Madagascar, may be characteristic of coastal sub-Saharan East Africa. Finally, the absence of any maternal contribution from Western Eurasia strongly implicates male-dominated trade and religion as the drivers of gene flow from the North. The Comoros provides a first view of the genetic makeup of coastal East Africa.

The human genetic history of Oceania: near and remote views of dispersal

The human history of Oceania is unique in the way that it encompasses both the first out-of-Africa expansion of modern humans to New Guinea and Australia as well as the last regional human occupation of Polynesia. Other anthropological peculiarities of Oceania include features like the extraordinarily rich linguistic diversity especially of New Guinea with about 1,000 often very distinct languages, the independent and early development of agriculture in the highlands of New Guinea about 10,000 years ago, or the long-term isolation of the entire region from the outside world, which lasted as long as until the 1930s for most of the interior of New Guinea. This review will provide an overview on the genetic aspects of human population history of Oceania and how some of the anthropological peculiarities are reflected in human genetic data. Due to current data availability it will mostly focus on insights from sex-specifically inherited mitochondrial DNA and Y-chromosomal DNA, whereas more genome-wide autosomal DNA data are soon expected to add additional details or may correct views obtained from these two, albeit highly complex, genetic loci.

Major east-west division underlies Y chromosome stratification across Indonesia

The early history of island Southeast Asia is often characterized as the story of two major population dispersals: the initial Paleolithic colonization of Sahul approximately 45 ka ago and the much later Neolithic expansion of Austronesian-speaking farmers approximately 4 ka ago. Here, in the largest survey of Indonesian Y chromosomes to date, we present evidence for multiple genetic strata that likely arose through a series of distinct migratory processes. We genotype an extensive battery of Y chromosome markers, including 85 single-nucleotide polymorphisms/indels and 12 short tandem repeats, in a sample of 1,917 men from 32 communities located across Indonesia. We find that the paternal gene pool is sharply subdivided between western and eastern locations, with a boundary running between the islands of Bali and Flores. Analysis of molecular variance reveals one of the highest levels of between-group variance yet reported for human Y chromosome data (e.g., Phi(ST) = 0.47). Eastern Y chromosome haplogroups are closely related to Melanesian lineages (i.e., within the C, M, and S subclades) and likely reflect the initial wave of colonization of the region, whereas the majority of western Y chromosomes (i.e., O-M119*, O-P203, and O-M95*) are related to haplogroups that may have entered Indonesia during the Paleolithic from mainland Asia. In addition, two novel markers (P201 and P203) provide significantly enhanced phylogenetic resolution of two key haplogroups (O-M122 and O-M119) that are often associated with the Austronesian expansion. This more refined picture leads us to put forward a four-phase colonization model in which Paleolithic migrations of hunter-gatherers shape the primary structure of current Indonesian Y chromosome diversity, and Neolithic incursions make only a minor impact on the paternal gene pool, despite the large cultural impact of the Austronesian expansion.

KIR3DL1/S1 genotypes and KIR2DS4 allelic variants in the AB KIR genotypes are associated with Plasmodium-positive individuals in malaria infection

The importance of innate immunity in malaria has been suggested for early protection from maturation and multiplication of Plasmodium parasites injected via infected mosquitoes. In this study, the killer cell immunoglobulin-like receptor (KIR) genes in innate immunity were investigated for an association with malaria in the comparison between Plasmodium-positive and Plasmodium-negative Melanesian individuals in the Solomon Islands, one of the most hyperendemic malaria regions in the world. The higher frequency of a pair of KIR3DL1 and KIR2DS4 was observed in the Plasmodium-positive individuals, which led to the investigation of KIR3DL1/S1 genotypes in concert with KIR2DS4 allelic variants. The positive individuals showed the highest frequency of KIR3DL1/KIR3DS1 heterozygosity, which might suggest the masking of activating KIR3DS1 by inhibitory KIR3DL1 at allelic levels to maintain the KIR3DS1-driven activation of natural killer cells diminished in controlling Plasmodium proliferation. The extended analysis with A/B genotypes further revealed the trend of parasitic positive individuals to be KIR3DL1/KIR3DS1 heterozygous in pair with KIR2DS4 nondeleted variants in a set of KIR genes inheritable as the AB genotypes. To the best of our knowledge, this study is the first KIR investigation of the malaria-infected population, which strengthened the potential associations of KIR with malaria pathogenesis. The balance of inhibitory and activating KIR3D genes (KIR3DL1/S1) and membrane-bound or secreted status of KIR2DS4 alleles in the interaction with the other KIR genes in the AB genotypes might constitute a part of KIR characteristics to determine resistance or susceptibility to Plasmodium parasitic infection.

Y-chromosome short tandem repeat intermediate variant alleles DYS392.2, DYS449.2, and DYS385.2 delineate new phylogenetic substructure in human Y-chromosome haplogroup tree

AIM

To determine the human Y-chromosome haplogroup backgrounds of intermediate-sized variant alleles displayed by short tandem repeat (STR) loci DYS392, DYS449, and DYS385, and to evaluate the potential of each intermediate variant to elucidate new phylogenetic substructure within the human Y-chromosome haplogroup tree.

METHODS

Molecular characterization of lineages was achieved using a combination of Y-chromosome haplogroup defining binary polymorphisms and up to 37 short tandem repeat loci. DNA sequencing and median-joining network analyses were used to evaluate Y-chromosome lineages displaying intermediate variant alleles.

RESULTS

We show that DYS392.2 occurs on a single haplogroup background, specifically I1*-M253, and likely represents a new phylogenetic subdivision in this European haplogroup. Intermediate variants DYS449.2 and DYS385.2 both occur on multiple haplogroup backgrounds, and when evaluated within specific haplogroup contexts, delineate new phylogenetic substructure, with DYS449.2 being informative within haplogroup A-P97 and DYS385.2 in haplogroups D-M145, E1b1a-M2, and R1b*-M343. Sequence analysis of variant alleles observed within the various haplogroup backgrounds showed that the nature of the intermediate variant differed, confirming the mutations arose independently.

CONCLUSIONS

Y-chromosome short tandem repeat intermediate variant alleles, while relatively rare, typically occur on multiple haplogroup backgrounds. This distribution indicates that such mutations arise at a rate generally intermediate to those of binary markers and STR loci. As a result, intermediate-sized Y-STR variants can reveal phylogenetic substructure within the Y-chromosome phylogeny not currently detected by either binary or Y-STR markers alone, but only when such variants are evaluated within a haplogroup context.

Genome-widely significant evidence of linkage of schizophrenia to chromosomes 2p24.3 and 6q27 in an SNP-Based analysis of Korean families

The present study reports the results of a genome-wide SNP linkage scan for schizophrenia in the Korean population. Fifty-six multiplex schizophrenia families were analyzed. Clinical evaluations on all subjects were consistently performed by raters in a single research team. Multipoint non-parametric linkage analysis was performed, and empirical simulations were generated to determine genome-wide significance. The authors found genome-widely significant evidence of linkage for schizophrenia to chromosomes 2p24.3 (NPL Z = 3.18) and 6q27 (NPL Z = 2.90). Six other chromosomal regions, that is, 3q24, 13q12.3, 18q22.3, 20p12.2, 4p14, and 1p36.12, yielded NPL Z scores of above 2.0 for either broad or narrow phenotype classes. Although linkage to these loci has not received prominent attention in studies on Caucasian families, multiple overlaps were observed between our loci (on 2p, 3q, and 13q) and linkage peaks generated from extended families in various isolated populations. Fine mappings and the detection of candidate genes within these regions are warranted.

The impact of the Austronesian expansion: evidence from mtDNA and Y chromosome diversity in the Admiralty Islands of Melanesia

The genetic ancestry of Polynesians can be traced to both Asia and Melanesia, which presumably reflects admixture occurring between incoming Austronesians and resident non-Austronesians in Melanesia before the subsequent occupation of the greater Pacific; however, the genetic impact of the Austronesian expansion to Melanesia remains largely unknown. We therefore studied the diversity of nonrecombining Y chromosomal (NRY) and mitochondrial (mt) DNA in the Admiralty Islands, located north of mainland Papua New Guinea, and updated our previous data from Asia, Melanesia, and Polynesia with new NRY markers. The Admiralties are occupied today solely by Austronesian-speaking groups, but their human settlement history goes back 20,000 years prior to the arrival of Austronesians about 3,400 years ago. On the Admiralties, we found substantial mtDNA and NRY variation of both Austronesian and non-Austronesian origins, with higher frequencies of Asian mtDNA and Melanesian NRY haplogroups, similar to previous findings in Polynesia and perhaps as a consequence of Austronesian matrilocality. Thus, the Austronesian language replacement on the Admiralties (and elsewhere in Island Melanesia and coastal New Guinea) was accompanied by an incomplete genetic replacement that is more associated with mtDNA than with NRY diversity. These results provide further support for the "Slow Boat" model of Polynesian origins, according to which Polynesian ancestors originated from East Asia but genetically mixed with Melanesians before colonizing the Pacific. We also observed that non-Austronesian groups of coastal New Guinea and Island Melanesia had significantly higher frequencies of Asian mtDNA haplogroups than of Asian NRY haplogroups, suggesting sex-biased admixture perhaps as a consequence of non-Austronesian patrilocality. We additionally found that the predominant NRY haplogroup of Asian origin in the Admiralties (O-M110) likely originated in Taiwan, thus providing the first direct Y chromosome evidence for a Taiwanese origin of the Austronesian expansion. Furthermore, we identified a NRY haplogroup (K-P79, also found on the Admiralties) in Polynesians that most likely arose in the Bismarck Archipelago, providing the first direct link between northern Island Melanesia and Polynesia. These results significantly advance our understanding of the impact of the Austronesian expansion and human history in the Pacific region.

The genetic structure of Pacific Islanders

Human genetic diversity in the Pacific has not been adequately sampled, particularly in Melanesia. As a result, population relationships there have been open to debate. A genome scan of autosomal markers (687 microsatellites and 203 insertions/deletions) on 952 individuals from 41 Pacific populations now provides the basis for understanding the remarkable nature of Melanesian variation, and for a more accurate comparison of these Pacific populations with previously studied groups from other regions. It also shows how textured human population variation can be in particular circumstances. Genetic diversity within individual Pacific populations is shown to be very low, while differentiation among Melanesian groups is high. Melanesian differentiation varies not only between islands, but also by island size and topographical complexity. The greatest distinctions are among the isolated groups in large island interiors, which are also the most internally homogeneous. The pattern loosely tracks language distinctions. Papuan-speaking groups are the most differentiated, and Austronesian or Oceanic-speaking groups, which tend to live along the coastlines, are more intermixed. A small “Austronesian” genetic signature (always <20%) was detected in less than half the Melanesian groups that speak Austronesian languages, and is entirely lacking in Papuan-speaking groups. Although the Polynesians are also distinctive, they tend to cluster with Micronesians, Taiwan Aborigines, and East Asians, and not Melanesians. These findings contribute to a resolution to the debates over Polynesian origins and their past interactions with Melanesians. With regard to genetics, the earlier studies had heavily relied on the evidence from single locus mitochondrial DNA or Y chromosome variation. Neither of these provided an unequivocal signal of phylogenetic relations or population intermixture proportions in the Pacific. Our analysis indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.

The origins and current genetic relationships of Pacific Islanders have been the subjects of interest and controversy for many decades. By analyzing the variation of a large number (687) of genetic markers in almost 1,000 individuals from 41 Pacific populations, and comparing these with East Asians and others, we contribute to the clarification and resolution of many of these issues. To judge by the populations in our survey, we find that Polynesians and Micronesians have almost no genetic relation to Melanesians, but instead are strongly related to East Asians, and particularly Taiwan Aborigines. A minority of Island Melanesian populations have indications of a small shared genetic ancestry with Polynesians and Micronesians (the ones that have this tie all speak related Austronesian languages). Inland groups who speak Papuan languages are particularly divergent and internally homogeneous. The genetic divergence among Island Melanesian populations, which is neatly organized by island, island size/topography, as well as their coastal or inland locations, is remarkable for such a small region, and enlarges our understanding of the texture of contemporary human variation.

Genome-wide analysis indicates more Asian than Melanesian ancestry of Polynesians

Analyses of mitochondrial DNA (mtDNA) and nonrecombining Y chromosome (NRY) variation in the same populations are sometimes concordant but sometimes discordant. Perhaps the most dramatic example known of the latter concerns Polynesians, in which about 94% of Polynesian mtDNAs are of East Asian origin, while about 66% of Polynesian Y chromosomes are of Melanesian origin. Here we analyze on a genome-wide scale, to our knowledge for the first time, the origins of the autosomal gene pool of Polynesians by screening 377 autosomal short tandem repeat (STR) loci in 47 Pacific Islanders and compare the results with those obtained from 44 Chinese and 24 individuals from Papua New Guinea. Our data indicate that on average about 79% of the Polynesian autosomal gene pool is of East Asian origin and 21% is of Melanesian origin. The genetic data thus suggest a dual origin of Polynesians with a high East Asian but also considerable Melanesian component, reflecting sex-biased admixture in Polynesian history in agreement with the Slow Boat model. More generally, these results also demonstrate that conclusions based solely on uniparental markers, which are frequently used in population history studies, may not accurately reflect the history of the autosomal gene pool of a population.

Y-chromosome short tandem repeat DYS458.2 non-consensus alleles occur independently in both binary haplogroups J1-M267 and R1b3-M405

AIM

To determine the human Y-chromosome haplogroup backgrounds of non-consensus DYS458.2 short tandem repeat alleles and evaluate their phylogenetic substructure and frequency in representative samples from the Middle East, Europe, and Pakistan.

METHODS

Molecular characterization of lineages was achieved using a combination of Y-chromosome haplogroup defining binary polymorphisms and up to 37 short tandem repeat loci, including DYS388 to construct haplotypes. DNA sequencing of the DYS458 locus and median-joining network analyses were used to evaluate Y-chromosome lineages displaying the DYS458.2 motif.

RESULTS

We showed that the DYS458.2 allelic innovation arose independently on at least two distinctive binary haplogroup backgrounds and possibly a third as well. The partial allele length pattern was fixed in all haplogroup J1 chromosomes examined, including its known rare sub-haplogroups. Within the alternative R1b3 associated M405 defined sub-haplogroup, both DYS458.0 and DYS458.2 allele classes occurred. A single chromosome also allocated to the R1b3-M269*(xM405) classification. The physical position of the partial insertion/deletion occurrence within the normal tetramer tract differed distinctly in each haplogroup context.

CONCLUSIONS

While unusual DYS458.2 alleles are informative, additional information for other linked polymorphic loci is required when using such non-conforming alleles to infer haplogroup background and common ancestry.

A comprehensive analysis of microsatellite diversity in Aboriginal Australians

Indigenous Australians have a unique evolutionary history that has resulted in a complex system of inter and intra-tribal relationships. While a number of studies have examined the population genetics of indigenous Australians, most have used a single sample to illuminate details of the global dispersal of modern humans and few studies have focussed on the population genetic features of the widely dispersed communities of the indigenous population. In this study we examine the largest Aboriginal Australian sample yet analysed (N = 8,868) at fifteen hypervariable autosomal microsatellite loci. A comprehensive analysis of differentiation indicates different levels of heterogeneity among indigenous peoples from traditional regions of Aboriginal Australia. The most genetically differentiated populations inhabit the North of the country, in particular the Tiwi of Melville and Bathurst islands, Arnhem Land (itself divided into West and East Arnhem), and Fitzmaurice regions. These tribal groups are most differentiated from other Aboriginal Australian tribes, especially those of the Central Desert regions, and also show marked heterogeneity from one another. These genetic findings are supportive of observations of body measurements, skin colour, and dermatoglyphic features which also vary substantially between tribes of the North (e.g. Arnhem Land) and Central Australian regions and, more specifically, between the Tiwi and West and East Arnhem tribes. This study provides the most comprehensive survey of the population genetics of Aboriginal Australia.

Human cranial anatomy and the differential preservation of population history and climate signatures

Cranial morphology is widely used to reconstruct evolutionary relationships, but its reliability in reflecting phylogeny and population history has been questioned. Some cranial regions, particularly the face and neurocranium, are believed to be influenced by the environment and prone to convergence. Others, such as the temporal bone, are thought to reflect more accurately phylogenetic relationships. Direct testing of these hypotheses was not possible until the advent of large genetic data sets. The few relevant studies in human populations have had intriguing but possibly conflicting results, probably partly due to methodological differences and to the small numbers of populations used. Here we use three-dimensional (3D) geometric morphometrics methods to test explicitly the ability of cranial shape, size, and relative position/orientation of cranial regions to track population history and climate. Morphological distances among 13 recent human populations were calculated from four 3D landmark data sets, respectively reflecting facial, neurocranial, and temporal bone shape; shape and relative position; overall cranial shape; and centroid sizes. These distances were compared to neutral genetic and climatic distances among the same, or closely matched, populations. Results indicate that neurocranial and temporal bone shape track neutral genetic distances, while facial shape reflects climate; centroid size shows a weak association with climatic variables; and relative position/orientation of cranial regions does not appear correlated with any of these factors. Because different cranial regions preserve population history and climate signatures differentially, caution is suggested when using cranial anatomy for phylogenetic reconstruction.

A mitochondrial stratigraphy for island southeast Asia

Island Southeast Asia (ISEA) was first colonized by modern humans at least 45,000 years ago, but the extent to which the modern inhabitants trace their ancestry to the first settlers is a matter of debate. It is widely held, in both archaeology and linguistics, that they are largely descended from a second wave of dispersal, proto-Austronesian-speaking agriculturalists who originated in China and spread to Taiwan approximately 5,500 years ago. From there, they are thought to have dispersed into ISEA approximately 4,000 years ago, assimilating the indigenous populations. Here, we demonstrate that mitochondrial DNA diversity in the region is extremely high and includes a large number of indigenous clades. Only a fraction of these date back to the time of first settlement, and the majority appear to mark dispersals in the late-Pleistocene or early-Holocene epoch most likely triggered by postglacial flooding. There are much closer genetic links to Taiwan than to the mainland, but most of these probably predated the mid-Holocene "Out of Taiwan" event as traditionally envisioned. Only approximately 20% at most of modern mitochondrial DNAs in ISEA could be linked to such an event, suggesting that, if an agriculturalist migration did take place, it was demographically minor, at least with regard to the involvement of women.

Extreme patterns of variance in small populations: placing limits on human Y-chromosome diversity through time in the Vanuatu Archipelago

Small populations are dominated by unique patterns of variance, largely characterized by rapid drift of allele frequencies. Although the variance components of genetic datasets have long been recognized, most population genetic studies still treat all sampling locations equally despite differences in sampling and effective population sizes. Because excluding the effects of variance can lead to significant biases in historical reconstruction, variance components should be incorporated explicitly into population genetic analyses. The possible magnitude of variance effects in small populations is illustrated here via a case study of Y-chromosome haplogroup diversity in the Vanuatu Archipelago. Deme-based modelling is used to simulate allele frequencies through time, and conservative confidence bounds are placed on the accumulation of stochastic variance effects, including diachronic genetic drift and contemporary sampling error. When the information content of the dataset has been ascertained, demographic models with parameters falling outside the confidence bounds of the variance components can then be accepted with some statistical confidence. Here I emphasize how aspects of the demographic history of a population can be disentangled from stochastic variance effects, and I illustrate the extreme roles of genetic drift and sampling error for many small human population datasets.

Melanesian and Asian Origins of Polynesians: mtDNA and Y Chromosome Gradients Across the Pacific

The human settlement of the Pacific Islands represents one of the most recent major migration events of mankind. Polynesians originated in Asia according to linguistic evidence or in Melanesia according to archaeological evidence. To shed light on the genetic origins of Polynesians, we investigated over 400 Polynesians from 8 island groups, in comparison with over 900 individuals from potential parental populations of Melanesia, Southeast and East Asia, and Australia, by means of Y chromosome (NRY) and mitochondrial DNA (mtDNA) markers. Overall, we classified 94.1% of Polynesian Y chromosomes and 99.8% of Polynesian mtDNAs as of either Melanesian (NRY-DNA: 65.8%, mtDNA: 6%) or Asian (NRY-DNA: 28.3%, mtDNA: 93.8%) origin, suggesting a dual genetic origin of Polynesians in agreement with the "Slow Boat" hypothesis. Our data suggest a pronounced admixture bias in Polynesians toward more Melanesian men than women, perhaps as a result of matrilocal residence in the ancestral Polynesian society. Although dating methods are consistent with somewhat similar entries of NRY/mtDNA haplogroups into Polynesia, haplotype sharing suggests an earlier appearance of Melanesian haplogroups than those from Asia. Surprisingly, we identified gradients in the frequency distribution of some NRY/mtDNA haplogroups across Polynesia and a gradual west-to-east decrease of overall NRY/mtDNA diversity, not only providing evidence for a west-to-east direction of Polynesian settlements but also suggesting that Pacific voyaging was regular rather than haphazard. We also demonstrate that Fiji played a pivotal role in the history of Polynesia: humans probably first migrated to Fiji, and subsequent settlement of Polynesia probably came from Fiji.

Paternal and maternal lineages in the Balkans show a homogeneous landscape over linguistic barriers, except for the isolated Aromuns

The Balkan Peninsula is a complex cultural mosaic comprising populations speaking languages from several branches of the Indo-European family and Altaic, as well as culturally-defined minorities such as the Aromuns who speak a Romance language. The current cultural and linguistic landscape is a palimpsest in which different peoples have contributed their cultures in a historical succession. We have sought to find any evidence of genetic stratification related to those cultural layers by typing both mtDNA and Y chromosomes, in Albanians, Romanians, Macedonians, Greeks, and five Aromun populations. We have paid special attention to the Aromuns, and sought to test genetically various hypotheses on their origins. MtDNA and Y-chromosome haplogroup frequencies in the Balkans were found to be similar to those elsewhere in Europe. MtDNA sequences and Y-chromosome STR haplotypes revealed decreased variation in some Aromun populations. Variation within Aromun populations was the primary source of genetic differentiation. Y-chromosome haplotypes tended to be shared across Aromuns, but not across non-Aromun populations. These results point to a possible common origin of the Aromuns, with drift acting to differentiate the separate Aromun communities. The homogeneity of Balkan populations prevented testing for the origin of the Aromuns, although a significant Roman contribution can be ruled out.

Investigating the effects of prehistoric migrations in Siberia: genetic variation and the origins of Yakuts

The Yakuts (also known as Sakha), Turkic-speaking cattle- and horse-breeders, inhabit a vast territory in Central and northeastern Siberia. On the basis of the archaeological, ethnographic and linguistic evidence, they are assumed to have migrated north from their original area of settlement in the vicinity of Lake Baykal in South Siberia under the pressure of the Mongol expansion during the thirteenth to fifteenth century AD: . During their initial migration and subsequent expansion, the ancestors of the Yakuts settled in the territory originally occupied by Tungusic- and Uralic-speaking reindeer-herders and hunters. In this paper we use mtDNA and Y-chromosomal analyses to elucidate whether the Yakut immigration and expansion was accompanied by admixture with the indigenous populations of their new area of settlement or whether the Yakuts displaced the original inhabitants without intermarriage. The mtDNA results show a very close affinity of the Yakuts with Central Asian and South Siberian groups, which confirms their southern origin. There is no conclusive evidence for admixture with indigenous populations, though a small amount cannot be excluded on the basis of the mtDNA data alone. The Y-chromosomal results confirm previous findings of a very strong bottleneck in the Yakuts, the age of which is in good accordance with the hypothesis that the Yakuts migrated north under Mongol pressure. Furthermore, the genetic results show that the Yakuts are a very homogenous population, notwithstanding their current spread over a very large territory. This confirms the historical accounts that they spread over their current area of settlement fairly recently.

Molecular insights into the origins of the Shompen, a declining population of the Nicobar archipelago

The Shompen, one of the most isolated and poorly understood contemporary hunter-gatherer populations, inhabit Great Nicobar Island, the southernmost island of the Nicobar archipelago. Morphological imprints in the Shompen were interpreted to favour a mixed Indo-Chinese, Malay, Negrito and Dravidian origin. Analyses of the mitochondrial, Y-chromosomal and autosomal gene pool of contemporary Shompen have revealed low diversity, illustrating a founder effect in the island population. Mitochondrial sequence analyses revealed the presence of two haplogroups of R lineage: B5a, and a newly defined clade, R12. Y-chromosomal analyses demonstrated the occurrence of a single lineage found predominantly in Austro-Asiatic speakers across Asia. With the different types of genetic markers analysed, the Shompen exhibit varying levels of genetic relatedness with the Nicobarese, and Austro-Asiatic speakers of mainland India and Southeast Asia. These genetic analyses provide evidence that the Shompen, an offshoot of the Nicobarese, are descendants of Mesolithic hunter-gatherers of Southeast Asian origin, deriving from at least two source populations.

Reconstructing the population history of Puerto Rico by means of mtDNA phylogeographic analysis

The haplogroup identities of 800 mtDNAs randomly and systematically selected to be representative of the population of Puerto Rico were determined by restriction fragment length polymorphism (RFLP), revealing maternal ancestries in this highly mixed population of 61.3% Amerindian, 27.2% sub-Saharan African, and 11.5% West Eurasian. West Eurasian frequencies were low in all 28 municipalities sampled, and displayed no geographic patterns. Thus, a statistically significant negative correlation was observed between the Amerindian and African frequencies of the municipalities. In addition, a statistically highly significant geographic pattern was observed for Amerindian and African mtDNAs. In a scenario in which Amerindian mtDNAs prevailed on either side of longitude 66 degrees 16' West, Amerindian mtDNAs were more frequent west of longitude 66 degrees 16' West than east of it, and the opposite was true for African mtDNAs. Haplogroup A had the highest frequency among Amerindian samples (52.4%), suggesting its predominance among the native Taínos. Principal component analysis showed that the sub-Saharan African fraction had a strong affinity to West Africans. In addition, the magnitudes of the Senegambian and Gulf of Guinea components in Puerto Rico were between those of Cape Verde and São Tomé. Furthermore, the West Eurasian component did not conform to European haplogroup frequencies. HVR-I sequences of haplogroup U samples revealed a strong North African influence among West Eurasian mtDNAs and a new sub-Saharan African clade.

Significant genetic differentiation between Poland and Germany follows present-day political borders, as revealed by Y-chromosome analysis

To test for human population substructure and to investigate human population history we have analysed Y-chromosome diversity using seven microsatellites (Y-STRs) and ten binary markers (Y-SNPs) in samples from eight regionally distributed populations from Poland (n = 913) and 11 from Germany (n = 1,215). Based on data from both Y-chromosome marker systems, which we found to be highly correlated (r = 0.96), and using spatial analysis of the molecular variance (SAMOVA), we revealed statistically significant support for two groups of populations: (1) all Polish populations and (2) all German populations. By means of analysis of the molecular variance (AMOVA) we observed a large and statistically significant proportion of 14% (for Y-SNPs) and 15% (for Y-STRs) of the respective total genetic variation being explained between both countries. The same population differentiation was detected using Monmonier's algorithm, with a resulting genetic border between Poland and Germany that closely resembles the course of the political border between both countries. The observed genetic differentiation was mainly, but not exclusively, due to the frequency distribution of two Y-SNP haplogroups and their associated Y-STR haplotypes: R1a1*, most frequent in Poland, and R1*(xR1a1), most frequent in Germany. We suggest here that the pronounced population differentiation between the two geographically neighbouring countries, Poland and Germany, is the consequence of very recent events in human population history, namely the forced human resettlement of many millions of Germans and Poles during and, especially, shortly after World War II. In addition, our findings have consequences for the forensic application of Y-chromosome markers, strongly supporting the implementation of population substructure into forensic Y chromosome databases, and also for genetic association studies.

Molecular analysis reveals tighter social regulation of immigration in patrilocal populations than in matrilocal populations

Human social organization can deeply affect levels of genetic diversity. This fact implies that genetic information can be used to study social structures, which is the basis of ethnogenetics. Recently, methods have been developed to extract this information from genetic data gathered from subdivided populations that have gone through recent spatial expansions, which is typical of most human populations. Here, we perform a Bayesian analysis of mitochondrial and Y chromosome diversity in three matrilocal and three patrilocal groups from northern Thailand to infer the number of males and females arriving in these populations each generation and to estimate the age of their range expansion. We find that the number of male immigrants is 8 times smaller in patrilocal populations than in matrilocal populations, whereas women move 2.5 times more in patrilocal populations than in matrilocal populations. In addition to providing genetic quantification of sex-specific dispersal rates in human populations, we show that although men and women are exchanged at a similar rate between matrilocal populations, there are far fewer men than women moving into patrilocal populations. This finding is compatible with the hypothesis that men are strictly controlling male immigration and promoting female immigration in patrilocal populations and that immigration is much less regulated in matrilocal populations.

The haematology of indigenous Australians

Prior to European settlement indigenous Australians were hunter-gatherers who lived in geographically isolated small clan groups, also separated by elaborate totemic rules. Today they still reside in isolated communities throughout Australia but many have moved to the cities. They share a high incidence of a range of health problems including cardiovascular disease, renal disease and infectious diseases largely attributed to a change to a more sedentary lifestyle. This paper reviews the haematology of indigenous Australians, including blood count, frequency and causes of anaemia, inherited risk factors for thrombophilia, blood groups and the incidence and types of haematological malignancies. There are some significant genetic differences between indigenous and non-indigenous Australians particularly in the frequency of blood groups, factor V Leiden and prothrombin mutations and presence of -alpha3.7 kb thalassaemia. These findings may have practical therapeutic implications (e.g. HPA phenotype for transfusion therapy and pregnancy risk) and in predicting disease risk. Other differences are acquired, related to lifestyle and living conditions (e.g. eosinophilia secondary to parasitic infections; iron and folate deficiencies), and are largely preventable.