The Polynesian gene pool: an early contribution by Amerindians to Easter Island

It is now generally accepted that Polynesia was first settled by peoples from southeast Asia. An alternative that eastern parts of Polynesia were first inhabited by Amerindians has found little support. There are, however, many indications of a 'prehistoric' (i.e. before Polynesia was discovered by Europeans) contact between Polynesia and the Americas, but genetic evidence of a prehistoric Amerindian contribution to the Polynesian gene pool has been lacking. We recently carried out genomic HLA (human leucocyte antigen) typing as well as typing for mitochondrial DNA (mtDNA) and Y chromosome markers of blood samples collected in 1971 and 2008 from reputedly non-admixed Easter Islanders. All individuals carried HLA alleles and mtDNA types previously found in Polynesia, and most of the males carried Y chromosome markers of Polynesian origin (a few had European Y chromosome markers), further supporting an initial Polynesian population on Easter Island. The HLA investigations revealed, however, that some individuals also carried HLA alleles which have previously almost only been found in Amerindians. We could trace the introduction of these Amerindian alleles to before the Peruvian slave trades, i.e. before the 1860s, and provide suggestive evidence that they were introduced already in prehistoric time. Our results demonstrate an early Amerindian contribution to the Polynesian gene pool on Easter Island, and illustrate the usefulness of typing for immunogenetic markers such as HLA to complement mtDNA and Y chromosome analyses in anthropological investigations.     

Dispersal and adaptive radiation of Bidens (Compositae) across the remote archipelagoes of Polynesia

The genus Bidens (Compositae) comprises c. 230 species distributed across five continents, with the 41 Polynesian species displaying the greatest ecomorphological variation in the group. However, the genus has had a long and complicated taxonomic history, and its phylogenetic and biogeographic history are poorly understood. To resolve the evolutionary history of the Polynesian Bidens, 152 individuals representing 91 species were included in this study, including 39 of the 41 described species from Polynesia. Four chloroplast and two nuclear DNA markers were utilized to estimate phylogenetic relationships, divergence times, and biogeographic history. Bidens was found to be polyphyletic within Coreopsis, consistent with previous assessments. The Polynesian radiation was resolved as monophyletic, with the initial dispersal into the Pacific possibly from South America to either the Hawaiian or Marquesas Islands. From the Marquesas, Bidens dispersed to the Society Islands, and ultimately to the Austral Islands. The initial diversification of the crown group in the Pacific is estimated to have occurred ~1.63 mya (0.74–2.72, 95% HPD), making Polynesian Bidens among the youngest and most rapid plant diversification events documented in the Pacific. Our findings suggest that relatively rare long‐distance dispersal and founder‐event speciation, coupled with subsequent loss of dispersal potential and within‐island speciation, can explain the repeated and explosive adaptive radiation of Bidens throughout the archipelagoes of Polynesia.     

A short history of Lagenaria siceraria (bottle gourd) in the Roman provinces: morphotypes and archaeogenetics

Lagenaria siceraria (Molina) Standl. (bottle gourd) is pantropic and displays large variation in fruit and seed shape. Two subspecies are currently recognized: the African L. siceraria ssp. siceraria and the Asian L. siceraria ssp. asiatica. The Asian type of bottle gourd belongs to the earliest domesticated plants in the Americas. In Europe, bottle gourd only appears with some frequency from the Roman period onwards. The paper is the study of ancient DNA (aDNA) and seed morphology of one almost complete bottle gourd fruit from the Roman site of Oedenburg/Biesheim–Kunheim, France (1st century a.d.), and from individual seed finds from the Roman vicus of Petinesca–Vorderberg, Switzerland (3rd century a.d.), both recovered from waterlogged layers. Width and length measurements of seeds show large variation. Based on the index of width to length, seeds from both sites differ significantly (p?<?0.0001 Mann–Whitney) suggesting that there were different variants present north of the Alps. Genetically, the bottle gourd fruit from Roman Oedenburg/Biesheim–Kunheim and one commercial cultivar L. siceraria cv. ‘Herkuleskeule’ are of Asian origin as identified by three Asian and African specific chloroplast markers. These results support an early and long-lasting presence of the Asian type of domestic bottle gourd in Europe. No chloroplast markers were found in the seeds from Petinesca–Vorderberg. However preserved nuclear high copy 5.8S rDNA fragments correctly matched to Cucurbitaceae, further supporting the evidence for preservation of DNA in waterlogged plant remains.     

The historic biogeography and community ecology of Polynesian pigeons and doves

The species richness, taxonomic diversity, and geographic distribution of pigeons and doves (Columbidae) have been altered irreversibly in Polynesia by 3500 years of human activity. Natural (without human influence) columbid faunas are estimated primarily by studying prehistoric bones. In all Polynesian island groups studied (except outlying Easter Island, Hawaiian Islands, or New Zealand), the prehistoric columbid faunas had more species, more genera, and more species per genus than modern faunas from the same island. Congeneric species pairs or triplets occurred on many islands for Ducula , Ptilinopus , and Gallicolumba. The losses of Polynesian columbids include the extinction of at least 9 species in the genera Ducula , Ptilinopus , Macropygia , Caloenas , Gallicolumba , and Didunculus as well as the extirpation of numerous island populations of extant species. If not for human impact, a typical East Polynesian island would support at least 5–6 species of columbids in 3–4 genera (compared to 0–3 species in 0–3 genera today). A typical West Polynesian island would support at least 6–7 species in 4–5 genera (compared to 1–6 species in 1–5 genera today). Since all Polynesian pigeons and doves are frugivorous and/or granivorous, their decline in recent millennia probably has affected the composition of Polynesian forests by limiting inter- and intra-island dispersal of plant propagules.     

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.     

Ancient voyaging and Polynesian origins

The "Polynesian motif" defines a lineage of human mtDNA that is restricted to Austronesian-speaking populations and is almost fixed in Polynesians. It is widely thought to support a rapid dispersal of maternal lineages from Taiwan ~4000 years ago (4 ka), but the chronological resolution of existing control-region data is poor, and an East Indonesian origin has also been proposed. By analyzing 157 complete mtDNA genomes, we show that the motif itself most likely originated >6 ka in the vicinity of the Bismarck Archipelago, and its immediate ancestor is >8 ka old and virtually restricted to Near Oceania. This indicates that Polynesian maternal lineages from Island Southeast Asia gained a foothold in Near Oceania much earlier than dispersal from either Taiwan or Indonesia 3-4 ka would predict. However, we find evidence in minor lineages for more recent two-way maternal gene flow between Island Southeast Asia and Near Oceania, likely reflecting movements along a "voyaging corridor" between them, as previously proposed on archaeological grounds. Small-scale mid-Holocene movements from Island Southeast Asia likely transmitted Austronesian languages to the long-established Southeast Asian colonies in the Bismarcks carrying the Polynesian motif, perhaps also providing the impetus for the expansion into Polynesia.     

Evolutionary history of the COII/tRNALys intergenic 9 base pair deletion in human mitochondrial DNAs from the Pacific

Length changes in human mitochondrial DNA (mtDNA) are potentially useful markers for inferring the evolutionary history of populations. One such length change is a nine base pair (9-bp) deletion that is located in the intergenic region between the COII gene and the Lysine tRNA gene (COII/tRNALys intergenic region). This deletion has been used as a genetic marker to trace descent from peoples of East Asian origin. A geographic cline of the deletion frequency across modern Pacific Islander populations suggests that the deletion may be useful for tracing prehistoric Polynesian origins and affinities. Mitochondrial DNA sequence variation within two variable segments of the control region (CR) permits a number of inferences regarding the evolutionary history of the 9-bp deletion that cannot be determined from frequency data alone. We obtained CR sequences from 74 mtDNAs with the 9-bp deletion from Indonesia, coastal Papua New Guinea (PNG), and American Samoa. Phylogenetic and pairwise distribution analysis of these CR sequences pooled with previously published CR sequences reveals that the deletion arose independently in Africa and Asia and suggests possible multiple origins of the deletion in Asia. A clinal increase of the frequency of the 9-bp deletion across the three Pacific populations is associated with a decrease in CR sequence diversity, consistent with founder events. Furthermore, analysis of pairwise difference distributions indicates an expansion time of proto-Polynesians that began 5,500 yr ago from Southeast Asia. These results are consistent with the express train model of Polynesian origins.      

Phylogeny and infrageneric classification of Symplocos (Symplocaceae) inferred from DNA sequence data

Symplocos comprises ～300 species of woody flowering plants with a disjunct distribution between the warm-temperate to tropical regions of eastern Asia and the Americas. Phylogenetic analyses of 111 species of Symplocos based on the nuclear ribosomal internal transcribed spacer (ITS) region and the chloroplast genes rpl16, matK, and trnL-trnF yielded topologies in which only one of the four traditionally recognized subgenera (Epigenia; Neotropics) is monophyletic. Section Cordyloblaste (subgenus Symplocos; eastern Asia) is monophyletic and sister to a group comprising all other samples of Symplocos. Section Palura (subgenus Hopea; eastern Asia) is sister to a group comprising all other samples of Symplocos except those of section Cordyloblaste. Symplocos wikstroemiifolia (eastern Asia) and S. tinctoria (southeastern United States), both of subgenus Hopea, form a clade that groups with S. longipes (tropical North America) and the species of subgenus Epigenia. The remaining samples of subgenus Hopea (eastern Asia) form a clade. Section Neosymplocos (subgenus Microsymplocos; Neotropics) is well nested within a clade otherwise comprising the samples of section Symplocastrum (subgenus Symplocos; Neotropics). Section Urbaniocharis (subgenus Microsymplocos; Antilles) groups as sister to the clade comprising Symplocastrum and Neosymplocos. The data support the independent evolution of deciduousness among section Palura and S. tinctoria. The early initial divergence of sections Cordyloblaste and Palura from the main group warrants their recognition at taxonomic levels higher than those at which they are currently placed. An inferred eastern Asian origin for Symplocos with subsequent dispersal to the Americas is consistent with patterns from other phylogenetic studies of eastern Asian-American disjunct plant groups but contrary to a North American origin inferred from the earliest fossil occurrences of the genus.     

Native American Y chromosomes in Polynesia: the genetic impact of the Polynesian slave trade

Since Thor Heyerdahl asserted that Polynesia was first colonized from the Americas (Heyerdahl 1950), geneticists have sought--but have not found--any evidence to support his theories. Here, Native American Y chromosomes are detected on the Polynesian island of Rapa. However, this, together with other odd features of the island's Y-chromosomal gene pool, is best explained as the genetic impact of a 19th century Peruvian slave trade in Polynesia. These findings underscore the need to account for history before turning to prehistory and the value of archival research to understanding modern genetic diversity. Although the impact of the Atlantic slave trade on the distribution of modern genetic diversity has been well appreciated, this represents the first study investigating the impact of this underappreciated episode on genetic diversity in the Pacific.     

The origins of the Polynesians: an interpretation from mitochondrial lineage analysis.

Using mitochondrial lineage analysis of 1,178 individuals from Polynesia, the western Pacific, and Taiwan, we show that the major prehistoric settlement of Polynesia was from the west and involved two or possibly three genetically distinct populations. The predominant lineage group, accounting for 94% of Polynesian mtDNA, shares a 9-bp COII/tRNA(Lys) intergenic deletion and characteristic control region transition variants, compared to the Cambridge reference sequence. In Polynesia, the diversity of this group is extremely restricted, while related lineages in Indonesia, the Philippines, and Taiwan are increasingly diverse. This suggests a relatively recent major eastward expansion into Polynesia, perhaps originating from Taiwan, in agreement with archeological and linguistic evidence, but which experienced one or more severe population bottlenecks. The second mitochondrial lineage group, accounting for 3.5% of Polynesian mtDNA haplotypes, does not have the 9-bp deletion and its characterized by an A-C transversional variant at nt position 16265. Specific oligonucleotides for this variant were used to select individuals from the population sample who, with other sequences, show that the Polynesian lineages were part of a diverse group in Vanuatu and Papua New Guinea. The very low overall diversity of both lineage groups in Polynesia suggests there was severe population restriction during the colonization of remote Oceania. A third group, represented by only four individuals (0.6%) in Polynesia but also present in the Philippines, shares variants at nt positions 16172 and 16304. Two Polynesians had unrelated haplotypes matching published sequences from native South Americans, which may be the first genetic evidence of prehistoric human contact between Polynesia and South America.     

The Hawaiian Archipelago is a stepping stone for dispersal in the Pacific: an example from the plant genus Melicope (Rutaceae)

Aim Pacific biogeographical patterns in the widespread plant genus Melicope J.R. Forst. & G. Forst. (Rutaceae) were examined by generating phylogenetic hypotheses based on chloroplast and nuclear ribosomal sequence data. The aims of the study were to identify the number of colonization events of Melicope to the Hawaiian Islands and to reveal the relationship of Hawaiian Melicope to the Hawaiian endemic genus Platydesma H. Mann. The ultimate goal was to determine if the Hawaiian Islands served as a source area for the colonization of Polynesia. Location Nineteen accessions were sampled in this study, namely eight Melicope species from the Hawaiian Islands, four from the Marquesas Islands, one species each from Tahiti, Australia and Lord Howe Island, two Australian outgroups and two species of the Hawaiian endemic genus Platydesma. To place our results in a broader context, 19 sequences obtained from GenBank were included in an additional analysis, including samples from Australia, Papua New Guinea, New Zealand, Southeast Polynesia and Asia. Methods DNA sequences were generated across 19 accessions for one nuclear ribosomal and three chloroplast gene regions. Maximum parsimony analyses were conducted on separate and combined data sets, and a maximum likelihood analysis was conducted on the combined nuclear ribosomal and chloroplast data set. A broader nuclear ribosomal maximum parsimony analysis using sequences obtained from GenBank was also performed. Geographic areas were mapped onto the combined chloroplast and nuclear ribosomal tree, as well as onto the broader tree, using the parsimony criterion to determine the dispersal patterns. Results Phylogenetic analyses revealed that Platydesma is nested within Melicope and is sister to the Hawaiian members of Melicope. The Hawaiian Melicope + Platydesma lineage was a result of a single colonization event, probably from the Austral region. Finally, Marquesan Melicope descended from at least one, and possibly two, colonization events from the Hawaiian Islands. Main conclusions These data demonstrate a shifting paradigm of Pacific oceanic island biogeography, in which the patterns of long‐distance dispersal and colonization in the Pacific are more dynamic than previously thought, and suggest that the Hawaiian Islands may act as a stepping stone for dispersal throughout the Pacific.     

Transferability of Cucurbita SSR markers for genetic diversity assessment of Turkish bottle gourd (Lagenaria siceraria) genetic resources

The genetic diversity present in crop landraces represents a valuable genetic resource for breeding and genetic studies. Bottle gourd (Lagenaria siceraria) landraces in Turkey are highly genetically diverse. However, the limited genomic resources available for this crop hinder the molecular characterization of Turkish bottle gourd germplasm for its adequate conservation and management. Therefore, we evaluated the efficacy of 40 SSR markers from major cucurbit crops (Cucurbita pepo L. and Cucurbita moschata L.) in 30 bottle gourd landraces, together with 16 SRAP primer combinations. In addition, we compared the genetic relationship between bottle gourd and 31 other cucurbit accessions (11 Cucurbita maxima, 3 C. moschata, 5 C. pepo subsp. ovifera, 10 C. pepo and 2 Luffa cylindrica). Twenty-seven Cucurbita SSR markers showed transferability to bottle gourd. SSR markers amplified 59 alleles, in bottle gourd genome with an average of 1.64 alleles per locus. Together, SSR and SRAP markers amplified 453 fragments across the 61 accessions, and clearly discriminated L. siceraria and L. cylindrica from the other cucurbit species. Genetic diversity analysis separated edible cucurbit from ornamentals, while population structure analysis classified L. siceraria in two subpopulations defined by fruit shape, rather than geographical origin. The results indicated that the genomic resources available for Cucurbita species are valuable to study and preserve the genetic diversity of bottle gourd in Turkey.     

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 phytogeographical affinities of the Pitcairn Islands – a model for south‐eastern Polynesia?

Aim To identify how the Pitcairn group relates biogeographically to the south‐eastern Polynesian region and if, as a subset of the regions flora, it can then be used as a model for biogeographical analyses. Location The Pitcairn group (25°4′ S, 130°06′ W) comprises four islands: Pitcairn, a relatively young, high volcanic Island; Henderson, an uplifted atoll, the uplift caused by the eruption of Pitcairn; and two atolls, Ducie and Oeno. The remote location, young age and range of island types found in the Pitcairn Island group makes the group ideal for the study of island biogeography and evolution. Methods A detailed literature survey was carried out and several data sets were compiled. Dispersal method, propagule number and range data were collected for each of the 114 species that occurs in the Pitcairn group, and environmental data was also gathered for islands in Polynesia. Analyses were carried out using non‐metric multidimensional scaling and clustering techniques. Results The flora of the Pitcairn Islands is derived from the flora of other island groups in the south‐eastern Polynesian region, notably those of the Austral, Society and Cook Islands. Species with a Pacific‐wide distribution dominate the overall Pitcairn group flora. However, each of the islands show different patterns; Pitcairn is dominated by species with Pacific, Polynesian and endemic distributions, with anemochory as the dominant dispersal method (39.5%); Henderson is also dominated by species with Pacific, Polynesian and endemic distributions, but zoochory is the dominant dispersal method (59.4); Oeno and Ducie are dominated by Pantropic species with hydrochory as the most common dispersal method (52.9% and 100%, respectively). Main conclusions ? Habitat availability is the most significant factor determining the composition and size of the flora. ? South‐east Polynesia is a valid biogeographical unit, and should include the Cook, Austral, Society, Marquesas, Gambier, Tuamotu and Pitcairn Islands with Rapa, but should exclude Easter Island, Tonga and Samoa. ? Regionalization schemes should take island type into consideration. ? The Pitcairn Island group can serve as a useful model for Pacific biogeographical analyses.     

Mitochondrial DNA data indicate an introduction through Mainland Southeast Asia for Australian dingoes and Polynesian domestic dogs

In the late stages of the global dispersal of dogs, dingoes appear in the Australian archaeological record 3500 years BP, and dogs were one of three domesticates brought with the colonization of Polynesia, but the introduction routes to this region remain unknown. This also relates to questions about human history, such as to what extent the Polynesian culture was introduced with the Austronesian expansion from Taiwan or adopted en route, and whether pre-Neolithic Australia was culturally influenced by the surrounding Neolithic world. We investigate these questions by mapping the distribution of the mtDNA founder haplotypes for dingoes (A29) and ancient Polynesian dogs (Arc1 and Arc2) in samples across Southern East Asia (n = 424) and Island Southeast Asia (n = 219). All three haplotypes were found in South China, Mainland Southeast Asia and Indonesia but absent in Taiwan and the Philippines, and the mtDNA diversity among dingoes indicates an introduction to Australia 4600-18 300 years BP. These results suggest that Australian dingoes and Polynesian dogs originate from dogs introduced to Indonesia via Mainland Southeast Asia before the Neolithic, and not from Taiwan together with the Austronesian expansion. This underscores the complex origins of Polynesian culture and the isolation from Neolithic influence of the pre-Neolithic Australian culture.     

Gene pools in wild Lima bean (Phaseolus lunatus L.) from the Americas: Evidences for an Andean origin and past migrations

The aims of this research were to assess the genetic structure of wild Phaseolus lunatus L. in the Americas and the hypothesis of a relatively recent Andean origin of the species. For this purpose, nuclear and non-coding chloroplast DNA markers were analyzed in a collection of 59 wild Lima bean accessions and six allied species. Twenty-three chloroplast and 28 nuclear DNA haplotypes were identified and shown to be geographically structured. Three highly divergent wild Lima bean gene pools, AI, MI, and MII, with mostly non-overlapping geographic ranges, are proposed. The results support an Andean origin of wild Lima beans during Pleistocene times and an early divergence of the three gene pools at an age that is posterior to completion of the Isthmus of Panama and major Andean orogeny. Gene pools would have evolved and reached their current geographic distribution mainly in isolation and therefore are of high priority for conservation and breeding programs.     

Biogeography of the fauna of French Polynesia: diversification within and between a series of hot spot archipelagos

The islands of French Polynesia cover an area the size of Europe, though total land area is smaller than Rhode Island. Each hot spot archipelago (Societies, Marquesas, Australs) is chronologically arranged. With the advent of molecular techniques, relatively precise estimations of timing and source of colonization have become feasible. We compile data for the region, first examining colonization (some lineages dispersed from the west, others from the east). Within archipelagos, blackflies (Simulium) provide the best example of adaptive radiation in the Societies, though a similar radiation occurs in weevils (Rhyncogonus). Both lineages indicate that Tahiti hosts the highest diversity. The more remote Marquesas show clear examples of adaptive radiation in birds, arthropods and snails. The Austral Islands, though generally depauperate, host astonishing diversity on the single island of Rapa, while lineages on other islands are generally widespread but with large genetic distances between islands. More recent human colonization has changed the face of Polynesian biogeography. Molecular markers highlight the rapidity of Polynesian human (plus commensal) migrations and the importance of admixture from other populations during the period of prehistoric human voyages. However, recent increase in traffic has brought many new, invasive species to the region, with the future of the indigenous biota uncertain.     

Characterization of polymorphic microsatellite markers for the blowfly Chrysomya albiceps (Diptera: Calliphoridae)

Chrysomya albiceps is a blowfly of great medical, sanitary and forensic importance widely distributed in the Afrotropical, southern Palaearctic, northern Oriental regions and, recently, in Central and South Americas. Here, we report the characterization of 13 polymorphic microsatellite markers for C. albiceps. The number of alleles ranged from three to 13 alleles with expected heterozygosities ranging from 0.4668 to 0.8408. These markers will be extremely useful for investigating many important aspects of this species such as population structure, dispersal and colonization dynamics.     

A three-genome phylogeny of Momordica (Cucurbitaceae) suggests seven returns from dioecy to monoecy and recent long-distance dispersal to Asia

The bitter gourd genus Momordica comprises 47 species in Africa and 12 in Asia and Australia. All have unisexual flowers, and of the African species, 24 are dioecious, 23 monoecious, while all Asian species are dioecious. Maximum likelihood analyses of 6257 aligned nucleotides of plastid, mitochondrial and nuclear DNA obtained for 122 accessions of Momordica and seven outgroups show that Momordica is monophyletic and consists of 11 well-supported clades. Monoecy evolved from dioecy seven times independently, always in Africa and mostly in savanna species with low population densities. Leaky dioecy, with occasional fruit-producing males, occurs in two African species and might be the first step in an evolutionary transition towards monoecy. Dated biogeographic analyses suggest that Momordica originated in tropical Africa and that the Asian species are the result of one long-distance dispersal event about 19 million years ago. The pantropical vegetable Momordica charantia is of African, not Asian origin as had previously been suggested.     

Genetic clues to the origin of the apple

Molecular genetic markers complement archaeological, breeding and geographical investigations of the origins, history and domestication of plants. With increasing access to wild apples from Central Asia, along with the use of molecular genetic markers capable of distinguishing between species, and explicit methods of phylogeny reconstruction, it is now possible to test hypotheses about the origin of the domesticated apple. Analyses of nuclear rDNA and chloroplast DNA (cpDNA) sequences indicate that the domesticated apple is most closely related to series Malus species. Moreover, the occurrence of a shared 18-bp duplication in the cpDNAs of wild and cultivated apple supports the close relationship between them. Hypotheses about the hybridization and the origin of the domesticated apple cannot be rejected completely until more variable, phylogenetically informative markers are found.