Patterns of molecular diversity in wild stocks of the redclaw crayfish (Cherax quadricarinatus) from northern Australia and Papua New Guinea: impacts of Plio-Pleistocene landscape evolution

1. Analysis of mitochondrial and nuclear DNA (microsatellites) in 379 individuals, collected from 15 localities in northern Australia and Papua New Guinea (PNG), demonstrated that wild redclaw crayfish ( Cherax quadricarinatus ) populations consist of two highly divergent Australian lineages and two PNG lineages.
2. The disjunction between the two Australian lineages occurs over a distance of approximately 200 km in the south-western corner of the Gulf of Carpenteria. These data conflict with an earlier study that detected no significant differentiation in 23 variable allozyme loci in redclaw sampled from northern Australia, but concur broadly with the previous recognition of two morphologically distinct species ( C. quadricarinatus and C. bicarinatus ) across northern Australia, and a third species in PNG ( C. albertsii ).
3. The inferred timing and patterns of divergence evident in the molecular data presented here closely align with a similar pattern reported in a co-distributed freshwater decapod crustacean, and broadly reflect patterns in some vertebrate taxa with similar distributions across northern Australia and PNG.
4. These congruent patterns most probably reflect periodic Plio-Pleistocene land and freshwater connections between Australia and New Guinea.     

Intraspecific phylogeography in the sedge frog Litoria fallax (Hylidae) indicates pre-Pleistocene vicariance of an open forest species from eastern Australia

The eastern sedge frog Litoria fallax (Anura: Hylidae) is common throughout the open forests and coastal wetlands along the eastern coast of Australia. Its range spans four biogeographical zones from northern Queensland to central New South Wales. Phylogenetic analysis of mitochondrial DNA (mtDNA) haplotypes of 87 L. fallax individuals from 22 populations identified two major mtDNA lineages, differing by 11-12% sequence divergence. The two clades of haplotypes were separated by the McPherson Range, indicating that this mesic upland area has acted as a major long-term barrier to gene flow for this open forest species. Slight isolation by distance was observed within both the northern and southern lineages but was insufficient to explain the large sequence divergence between lineages. Within the northern lineage, additional phylogeographical structure was observed across the relatively dry Burdekin Gap which separates Atherton populations from all populations in the central and eastern Queensland biogeographical zones. There was less phylogeographical structure in the southern lineage suggesting historical gene flow across the drier portions of the Great Dividing Range. These data, together with recent observations of deep phylogeographical divergences in rainforest-restricted Litoria suggest that the east coast hylids of Australia represent an old (Tertiary) radiation. Individual species of Litoria have been strongly affected by climatic and ecological barriers to gene flow during the Quaternary.     

Hierarchical organization of genetic variation in the Costa Rican livebearing fish Brachyrhaphis rhabdophora (Poeciliidae)

I examined the geographic distribution of genetic variation in the livebearing freshwater fish Brachyrhaphis rhabdophora in northwestern Costa Rica as revealed by allozymes and mitochondrial DNA sequences. Allelic variability at 11 enzyme-coding loci surveyed across 12 localities revealed marked genetic differentiation among populations within drainages (0_P= 0.36) and among drainages within regions (0_D=0.17), but not between northern and southern geographic regions (0_R=– 0.02). Allozyme variation was hierarchically organized such that populations found within stream drainages were more similar to each other than to populations found in adjacent drainages, a result confirmed by cluster analysis. In contrast to the allozyme data, there was extremely little DNA sequence variation among populations in the mitochondrial control region (3 variable nucleotide positions out of 444 bp examined). The difference in genetic divergence between allozyme and mtDNA markers was unexpected and is discussed in terms of biogeographical colonization events and a molecular selective swéep on the mitochondrial genome, both processes that could explain the lack of mitochondrial variability in this highly subdivided species.     

Population structure and phylogeography of the short-tailed stingray, Dasyatis brevicaudata (Hutton 1875), in the Southern Hemisphere

There is accumulating evidence that the degree of vagility explains little of the extent of population subdivision found within elasmobranch species. Instead, patterns of gene flow in elasmobranchs appear more closely linked to the presence of dispersal barriers, either physical or biological. Here, we investigate the potential role of some of these isolating mechanisms in shaping the population structure of a member of the stingray family Dasyatidae (Dasyatis brevicaudata) at various scales (southern hemisphere vs. coastal New Zealand). Analyses of the mitochondrial DNA control region from 176 individuals revealed significant genetic structure between South Africa, Australia, and New Zealand populations (analysis of molecular variance [AMOVA], overall Ф(ST) = 0.67, P < 0.001), although New Zealand and Australia shared some haplotypes. Surprisingly, significant population differentiation was found among several coastal New Zealand locations (AMOVA, overall Ф(ST) = 0.05, P < 0.05). However, data did not support the genetic differentiation between individuals from an offshore breeding area and mainland individuals. Comparisons suggest that these stingrays exhibit similar levels of population differentiation as other coastal elasmobranchs, with high divergence across oceanic basins and lower differentiation along continuous coastal habitats. Differences in coastal population structuring in elasmobranch species studied to date may be attributed to species-specific preferences for coastal habitats, which may be linked to life history functions (e.g., feeding and pupping).     

Phylogeography of the Ryukyu robin (Erithacus komadori): population subdivision in land-bridge islands in relation to the shift in migratory habit

We analysed the mitochondrial control region sequences of 150 Ryukyu robins (Erithacus komadori) from five migratory and three sedentary populations. E. komadori is endemic to the subtropical Asian islands, is well differentiated among populations in morphology and migratory behaviour within its narrow habitat range, and is ideal for examining the effects of altered migratory habits on population differentiation. Maximum-likelihood analysis among the haplotypes resulted in the generation of a single tree in which two phylogenetic clades corresponding to the two subspecies were evident. Within the northern lineage, three distinctive subgroups of populations (one migratory and two sedentary groups) were observed by population genetic analysis. The migration-related wing morphology and molecular data were then compared among groups. The wing shape of the northern lineage was significantly more pointed than that of the southern sedentary lineage, and they were exclusively discriminated from each other. The difference was not so apparent between the sedentary and migratory groups within the northern lineage, suggesting that the present northern subspecies is primarily a migratory lineage. The different migratory behaviours of the robin played an apparent role in maintaining the genetic structure at two different levels--one between the southern and northern lineages and the other between the sedentary and migratory groups within the northern lineage. While gene flow had long been maintained among the islands occupied by migratory individuals, migrants have been unable to contribute to the gene pool of the sedentary populations despite passing through the breeding range of such populations twice each year.     

Systematics of dusky salamanders, Desmognathus (Caudata: Plethodontidae), in the mountain and Piedmont regions of Virginia and North Carolina, USA

We analysed mitochondrial (cytochrome  b ) nucleotide sequences, nuclear allozyme markers, and morphometric characters to investigate species boundaries and phylogenetic relationships among dusky salamanders ( Desmognathus ) in the southern Blue Ridge and adjacent Piedmont Physiographic Provinces of Virginia and North Carolina. Our results revealed four distinct mitochondrial DNA clades that are also characterized by distinct allozyme markers. One clade consists of sequences derived from populations distributed from New England to south-western Virginia that are referable to Desmognathus fuscus Rafinesque, 1820, although there is considerable sequence and allozyme divergence within this clade. A second clade consists of sequences derived from populations referable to Desmognathus planiceps Newman, 1955, a form that we resurrect from its long synonymy under D. fuscus . Desmognathus planiceps and D. fuscus also differ in mandibular tooth shape. Two other cytochrome  b sequences recovered from populations along the Blue Ridge escarpment in southern Virginia are quite divergent from those of the previous two clades, and these populations may represent yet another distinct species. Sequences from a population in the Brushy Mountains in the Piedmont of northern North Carolina are similar to those of Desmognathus carolinensis . Population groupings indicated by allozyme data generally correspond to the cytochrome  b clades. Cryptic diversity in Appalachian desmognathan salamanders clearly requires further study. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 115–130.     

Glinal variation in morphology among eastern populations of the waterstrider, Aquarius remigis Say (Hemiptera: Gerridae)

We examined morphological variation among populations of the stream-dwelling waterstrider, Aquarius remigis. A previous analysis of allozyme variation along a transect from southern Quebec to southern North Carolina revealed two distinct 'types' of A. remigis, north and south of a transition zone in southern New York and northern Pennsylvania. To assess the concordance of morphological and allozyme differentiation, adults were sampled from 15 populations along the original transect, as well as 11 additional populations in New York, Connecticut and New Jersey. Eight measurements of leg and body size were taken of preserved individuals. Univariate and multivariate analyses (multiple regression, PCA, discriminant analysis) reveal significant differentiation between northern and southern populations with a transition zone between latitudes 39^oand 42^onorth. Strong clines within each region and a clear transition between regions support previous suggestions that there are two distinct 'types' of this species in eastern North America. The transition zone, in morphology coincides with that revealed by the allozyme variation, but extends further south. The covariance of allozyme frequency and morphometric traits suggests that differentiation has occurred through vicariance and secondary contact, and that in this system, cladistic and adaptive differentiation are coupled.     

Phylogenetic analyses of mtDNA sequences reveal three cryptic lineages in the widespread neotropical frog Leptodactylus fuscus (Schneider, 1799) (Anura, Leptodactylidae)

Leptodactylus fuscus is a neotropical frog ranging from Panamá to Argentina, to the east of the Andes mountains, and also inhabiting Margarita, Trinidad, and the Tobago islands. We performed phylogenetic analyses of 12S rRNA, 16S rRNA, tRNA-Leu, and ND1 mitochondrial (mt) DNA sequences from specimens collected across the geographic distribution of L. fuscus to examine two alternative hypotheses: (i) L. fuscus is a single, widely distributed species, or (ii) L. fuscus is a species complex. We tested statistically for geographic association and partitioning of genetic variation among mtDNA clades. The mtDNA data supported the hypothesis of several cryptic species within L. fuscus. Unlinked mtDNA and nuclear markers supported independently the distinctness of a 'northern' phylogenetic unit. In addition, the mtDNA data divided the southern populations into two clades that showed no sister relationship to each other, consistent with high differentiation and lack of gene flow among southern populations as suggested by allozyme data. Concordance between mtDNA and allozyme patterns suggests that cryptic speciation has occurred in L. fuscus without morphological or call differentiation. This study illustrates a case in which lineage splitting during the speciation process took place without divergence in reproductive isolation mechanisms (e.g. advertisement call in frogs), contrary to expectations predicted using a biological species framework.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 325–341. No claim to original US government works.     

Crossing the Tasman Sea: Inferring the introduction history of Litoria aurea and Litoria raniformis (Anura: Hylidae) from Australia into New Zealand

Abstract The amphibian fauna of New Zealand consists of three native species (Leiopelma spp.), and three Litoria species introduced from Australia in the last 140 years. We conducted a molecular phylogeographical study that aimed to identify the Australian origins of two species, Litoria aurea and Litoria raniformis. We used partial sequences of the mitochondrial cytochrome oxidase I (cox1) gene from 59 specimens sampled from across the range of both species to identify the probable source populations for the New Zealand introductions, and to describe the current genetic diversity among New Zealand Litoria populations. Our genetic data suggest that L. aurea was introduced into the North Island of New Zealand from two regions in Australia, once from the northern part of coastal New South Wales and once from the southern part of coastal New South Wales. Our data indicate that L. raniformis introductions originated from the Melbourne region of southern Victoria and once established in the South Island of New Zealand, the species subsequently spread throughout both islands. In addition, we found a distinct haplotype in L. raniformis from Tasmania that strongly suggests, contrary to earlier reports, that this species was not introduced into New Zealand from Tasmania. Finally, we identified two very distinctive mitochondrial lineages of L. raniformis within the mainland Australia distribution, which may be previously unrecognized species.     

Genetic variation in populations of the morphologically and ecologically variable fern Stegnogramma pozoi subsp. mollissima (Thelypteridaceae) in Japan

In Japanese Stegnogramma pozoi subsp. mollissima (Fisher ex Kunze) K. Iwats. there is the intrasubspecific variation among rbcL sequences. Northern and southern plants are genetically differentiated for maternally inherited cpDNA. In the present study we examined allozyme polymorphisms to test the hypothesis that northern and southern plants may be separate species. Based on allozyme data, the degree of gene flow among populations was estimated to be large. The artificial crossing experiments between cpDNA haplotypes also suggested that isolation has not developed among these cpDNA haplotypes. However, interpopulation genetic differentiation in cpDNA was observed even in the small area at the foot of Mt. Hakone, and the cpDNA haplotypes appear to have different habitat preferences.     

The invasion biology of the invasive earwig, <Emphasis Type="Italic">Forficula auricularia</Emphasis> in Australasian ecosystems

The European earwig, Forficula auricularia, is a cosmopolitan insect endemic to Europe, West Asia and North Africa, which has invaded many temperate regions of the world including Australia and New Zealand. F. auricularia has been shown to be a complex of morphologically identical, reproductively isolated lineages that possess two distinct clades of mitochondrial DNA. Entomological collection data, historical literature and further field collections were used to develop a greater understanding of Australian F. auricularia’s invasion biology and its current distribution. Genetic analysis of F. auricularia collected from Australia and New Zealand using two mitochondrial genes (COI and a fragment overlapping parts of the COI -COII genes) was also undertaken. To identify the possible source populations of the Australasian invasion these sequences were compared to those from 16 locations within Britain and continental Europe. All Australasian populations were shown to be of the clade B lineage. Tasmanian and New Zealand populations consist of a single subclade comprised of only 4 and 1 haplotypes respectively. The Australian mainland populations also contained a second subclade consisting of up to 11 haplotypes indicating that multiple introductions possibly occurred on the Australian mainland. Comparison of mitochondrial genomes from Australasian and European populations showed the Australian mainland subclade to be most closely related to Portuguese haplotypes, and the Tasmanian and New Zealand clade closely related to those in Brittany, France. No European haplotypes perfectly matched the Australasian sequences. Therefore, the original source populations are still to be identified with harbours on the Iberian Peninsula’s western coast and those on the English Channel likely candidate areas.     

DNA barcoding confirms polyphagy in a generalist moth,Homona mermerodes (Lepidoptera: Tortricidae)

Recent DNA barcoding of generalist insect herbivores has revealed complexes of cryptic species within named species. We evaluated the species concept for a common generalist moth occurring in New Guinea and Australia, Homona mermerodes, in light of host plant records and mitochondrial cytochrome c oxidase I haplotype diversity. Genetic divergence among H. mermerodes moths feeding on different host tree species was much lower than among several Homona species. Genetic divergence between haplotypes from New Guinea and Australia was also less than interspecific divergence. Whereas molecular species identification methods may reveal cryptic species in some generalist herbivores, these same methods may confirm polyphagy when identical haplotypes are reared from multiple host plant families. A lectotype for the species is designated, and a summarized bibliography and illustrations including male genitalia are provided for the first time.     

Genetic analysis of southern African gemsbok (Oryx gazella) reveals high variability, distinct lineages and strong divergence from the East African Oryx beisa

We carried out a population genetic analysis of five southern African gemsbok (Oryx gazella) populations based on 530 bp of the mitochondrial control region and ten microsatellites in 75 individuals. Both markers show the high variability often observed in African bovids. Three of the populations which can be traced back to very small founding or current sizes do not show any signs of reduced variability compared to the remaining populations. The mitochondrial haplotypes form three distinct lineages which most likely originated in the Pleistocene when climate fluctuations led to periodical reduction and spreading of gemsbok habitat and which, today, are found throughout the distribution range. Bayesian microsatellite analyses yielded two groups, suggesting a more recent geographical differentiation following the admixture of the mtDNA lineages. Combining our sequences with available published data of the remaining oryx species allowed for a direct molecular comparison of O. gazella and O. beisa which have sometimes been considered a single species. The average genetic divergence between haplotypes from the two taxa was very high (39.9%), supporting their classification into two different species.     

Phylogeography of the tailed frog (Ascaphus truei): implications for the biogeography of the Pacific Northwest

Tailed frogs are distributed in high-gradient streams within the disjunct mesic forests of the Pacific Northwest and represent the basal lineage of the anurans. We sequenced 1,530 nucleotides of the mitochondrial cytochrome b and NADH dehydrogenase subunit two genes from 23 populations and used parsimony, maximum-likelihood, and nested-clade analyses to estimate relationships among populations and infer evolutionary processes. We found two divergent haplotype clades corresponding with inland Rocky Mountain populations and coastal populations and separated by up to 0.133 substitutions per site. Within the coastal assemblage, haplotypes formed clades by mountain range with 0.010-0.024 substitutions per site divergence among populations. Inland haplotypes exhibited minimal genetic structure, with the exception of 0.021 substitutions per site distance between populations from the East Fork of the South Fork of the Salmon River and all other inland haplotypes. The magnitude of divergence between inland and coastal populations, as well as the paleobotanical record, suggest isolation of these lineages occurred during the late Miocene to early Pliocene, probably in response to the rise of the Cascade Mountains. Genetic structure within coastal and inland populations is consistent with isolation in refugia during the late Pliocene and early Pleistocene. Closely related inland haplotypes reflect range expansion following glaciation. The depth of divergence between inland and coastal populations supports the persistence of mesic forests within the inland Pacific Northwest throughout the Pleistocene and is congruent with patterns found in several other mesic forest species. Based on mitochondrial divergence and previous allozyme and morphological data, we recommend recognition of inland populations as a distinct species, Ascaphus montanus.     

Genetic diversity and biogeography of native and introduced populations of Ulva pertusa (Ulvales,Chlorophyta)

Genetic diversity of native and introduced populations of Ulva pertusa (Ulvales, Chlorophyta) was examined using genetic markers of chloroplast, mitochondria and nuclear non‐coding region sequences. In the preliminary investigations to genetically identify the species for further analyses, U. pertusa was found only from temperate coasts of the more extensive collection sites including tropical coasts suggesting that it is a temperate species and basically not distributed in tropical regions. For chloroplast and mitochondrial sequences, repeating patterns of short tandem repeat sequences and nucleotide substitutions were used to recognize the haplotypes (genetic types). A total of 48 haplotypes based on combinations of chloroplast and mitochondrial haplotypes were recognized in the 244 specimens collected in the presumptive native range (Northeast Asia) and introduced populations (North America, Australia, New Zealand, Chile and Europe). Among them, 46 haplotypes (H1–H8 and H11–H48) were recognized in Northeast Asia, whereas only 1–5 haplotypes were recognized in the other areas. Nuclear microsatellite sequences were also analyzed. The lengths of the PCR products including the nuclear microsatellite region of 234 specimens were determined, and a total of 17 genotypes were recognized. Among them, 14 genotypes were found in Northeast Asia, whereas 1–7 genotypes were recognized in the other areas. Based on the results, the hypothesis that the native range of the species is in Northeast Asia was supported, and the populations outside this range were concluded to be non‐indigenous populations.     

Mitochondrial differentiation in a polymorphic land snail: evidence for Pleistocene survival within the boundaries of permafrost

The genetic differentiation of populations having colonized formerly unsuitable habitats after the Pleistocene glaciations depends to a great extent on the speed of expansion. Slow dispersers maintain their refugial diversity whereas fast dispersal leads to a reduction of diversity in the newly colonized areas. During the Pleistocene, almost the entire current range of the land snail Arianta arbustorum has repeatedly been covered with ice or been subjected to permafrost. Owing to the low potential for dispersal of land snails, slow (re)colonization of the wide range from southern refugia can be excluded. Alternatively, fast, passive dispersal from southern refugia or survival in and expansion from multiple refugia within the area subjected to permafrost may account for the current distribution. To distinguish between these scenarios we reconstructed a phylogeography based on the sequences of a fragment of the cytochrome oxidase I from 133 individuals collected at 45 localities and analysed the molecular variance. Seventy-five haplotypes were found that diverged on average at 7.52% of positions. This high degree of diversity suggests that A. arbustorum is an old species in which the population structure, isolation and the hermaphroditic nature have reduced the probability of lineage extinction. The genetic structure was highly significant with the highest variance partition found among regions. Geographic distance and mitochondrial differentiation were not congruent. Lineages had overlapping ranges. The clear genetic differentiation and the patchy pattern of haplotype distribution suggest that colonization of formerly unsuitable habitats was mainly achieved from multiple populations from within the permafrost area.     

Some butterflies do not care much about topography: a single genetic lineage of Erebia euryale (Nymphalidae) along the northern Iberian mountains

The phylogeography of montane species often reveals strong genetic differentiation among mountain ranges. Both classic morphological and genetic studies have indicated distinctiveness of Pyrenean populations of the butterfly Erebia euryale. This hypothesis remained inconclusive until data from the westernmost populations of the distribution area (Cantabrian Mountains) were analysed. In the present study, we set out to describe the population structure of Erebia euryale in western Cantabria, where the species occurs in scattered localities. For this goal, we estimate the genetic diversity and differentiation found in 218 individuals from six Cantabrian (North Spain) localities genotyped by 17 allozyme loci. We also sequence 816 bp of the cytochrome oxidase subunit I mitochondrial gene in 49 individuals from Cantabrian localities and 41 specimens from five other European sites. Mitochondrial data support the recognition of four major genetic groups previously suggested for the European populations based on allozyme polymorphisms. Both mitochondrial and nuclear markers reveal genetic distinctiveness of a single Pyrenean–Cantabrian lineage of E. euryale. The lack of geographical structure and the star‐like topology displayed by the mitochondrial haplotypes indicate a pattern of demographic expansion in northern Iberia, probably related to Upper Pleistocene climatic oscillations. By contrast, within the Pyrenean–Cantabrian lineage, Cantabrian samples are genetically structured in nuclear datasets. In particular, San Isidro is significantly differentiated from the other five populations, which cluster into two groups. We recognize an evolutionary significant unit for Pyrenean–Cantabrian populations of Erebia euryale. Our results also illustrate that the evolutionary history of a species may be shaped by processes undetectable by using mtDNA alone.     

Genetic relationships among populations of wild resident, and wild and hatchery anadromous brook charr

To determine the genetic relationship of anadromous and resident life-history types within and among drainages, and compare several hatchery strains to their progenitor populations, brook charr Salvelinus fontinalis were examined for allozyme and mitochondrial DNA variation. Greater genetic similarity of sympatric anadromous and resident charr was found compared to similar life-history forms allopatrically, suggesting the two life-history types are not reproductively isolated. Low divergence among the mtDNA haplotypes suggests that the two life-history types are members of the same evolutionary lineage. Population differentiation from mtDNA data exceeded that from estimates based on allozymes. Genetic deviations from expectations suggest that the hatchery strains were derived from few individuals.     

Mitochondrial haplotypes and the New Zealand origin of clonal European Potamopyrgus, an invasive aquatic snail

The small aquatic snail Potamopyrgus antipodarum is an important invading species in Europe, Australia and North America. European populations are generally believed to derive from accidental introductions from New Zealand, probably dating back to the mid-19th century. We have employed mitochondrial DNA sequences to test the proposed New Zealand origin of European Potamopyrgus, and to learn more about its genealogical history. Using a 481-bp region of the 16S ribosomal RNA gene, we identified 17 distinct haplotypes among 65 snails from New Zealand. In marked contrast, only two haplotypes were found across all European samples, which cover a large geographical area. Importantly, these two haplotypes are shared with snails from the North Island of New Zealand. Due to sampling limitations we cannot rule out a South Island origin for one of the haplotypes, but our results clearly demonstrate the New Zealand origin of European populations. The marked divergence among the two European haplotypes implies the successful colonization by two distinct mitochondrial lineages, which is consistent with previous data based on nuclear markers.     

Reduced Y-chromosome,but not mitochondrial DNA,diversity in human populations from West New Guinea

To investigate the paternal population history of New Guinea, 183 individuals from 11 regional populations of West New Guinea (WNG) and 131 individuals from Papua New Guinea (PNG) were analyzed at 26 binary markers and seven short-tandem-repeat loci from the nonrecombining part of the human Y chromosome and were compared with 14 populations of eastern and southeastern Asia, Polynesia, and Australia. Y-chromosomal diversity was low in WNG compared with PNG and with most other populations from Asia/Oceania; a single haplogroup (M-M4) accounts for 75% of WNG Y chromosomes, and many WNG populations have just one Y haplogroup. Four Y-chromosomal lineages (haplogroups M-M4, C-M208, C-M38, and K-M230) account for 94% of WNG Y chromosomes and 78% of all Melanesian Y chromosomes and were identified to have most likely arisen in Melanesia. Haplogroup C-M208, which in WNG is restricted to the Dani and Lani, two linguistically closely related populations from the central and western highlands of WNG, was identified as the major Polynesian Y-chromosome lineage. A network analysis of associated Y-chromosomal short-tandem-repeat haplotypes suggests two distinct population expansions involving C-M208--one in New Guinea and one in Polynesia. The observed low levels of Y-chromosome diversity in WNG contrast with high levels of mtDNA diversity reported for the same populations. This most likely reflects extreme patrilocality and/or biased male reproductive success (polygyny). Our data further provide evidence for primarily female-mediated gene flow within the highlands of New Guinea but primarily male-mediated gene flow between highland and lowland/coastal regions.