Polynesian Region Research Articles

Pogostemon guamensis Lorence & W.L.Wagner (Lamiaceae), a new species from Guam, Mariana Islands.

While undertaking a botanical survey of the Andersen Air Force Base on Guam (Mariana Islands) in 1994, botanists from the National Tropical Botanical Garden collected an unusual suffrutescent, non-aromatic member of the Lamiaceae family growing on limestone cliffs in the northeastern part of the island. Based on morphology and molecular data (trnLF, matK), it was determined to belong to the genus Pogostemon Desf., a genus previously unknown from the Micronesian, Melanesian, and Polynesian region. Moreover, the analysis also showed that it was not conspecific with P. cablin (patchouli), and of the species available to include in the phylogenetic analyses it is sister to P. hirsutus¸ a species from India and Sri Lanka. Differing from its congeners by its large, loose inflorescence 2.5–5 cm wide and up to 7 cm wide in fruit, it is here illustrated and described as a new species, Pogostemon guamensis Lorence & W.L. Wagner and its habitat and conservation status are discussed.

Early Lapita skeletons from Vanuatu show Polynesian craniofacial shape: Implications for Remote Oceanic settlement and Lapita origins

With a cultural and linguistic origin in Island Southeast Asia the Lapita expansion is thought to have led ultimately to the Polynesian settlement of the east Polynesian region after a time of mixing/integration in north Melanesia and a nearly 2,000-y pause in West Polynesia. One of the major achievements of recent Lapita research in Vanuatu has been the discovery of the oldest cemetery found so far in the Pacific at Teouma on the south coast of Efate Island, opening up new prospects for the biological definition of the early settlers of the archipelago and of Remote Oceania in general. Using craniometric evidence from the skeletons in conjunction with archaeological data, we discuss here four debated issues: the Lapita-Asian connection, the degree of admixture, the Lapita-Polynesian connection, and the question of secondary population movement into Remote Oceania.

Use of Pollen and Ancient DNA as Conservation Baselines for Offshore Islands in New Zealand

Islands play a key role globally in the conservation of endemic species. Many island reserves have been highly modified since human colonization, and their restoration and management usually occur without knowledge of their prehuman state. However, conservation paleoecology is increasingly being recognized as a tool that can help to inform both restoration and conservation of island reserves by providing prehuman vegetation baselines. Many of New Zealand's mammal-free offshore islands are foci for biological diversity conservation and, like many islands in the Polynesian region, were deforested following initial human settlement. Therefore, their current restoration, replanting, and management are guided either by historic vegetation descriptions or the occurrence of species on forested islands. We analyzed pollen and ancient DNA in soil cores from an offshore island in northern New Zealand. The result was a 2000-year record of vegetation change that began >1200 years before human settlement and spanned 550 years of human occupation and 180 years of forest succession since human occupation ceased. Between prehuman and contemporary forests there was nearly a complete species turnover including the extirpation of a dominant conifer and a palm tree. The podocarp-dominated forests were replaced by a native but novel angiosperm-dominated forest. There is no modern analog of the prehuman forests on any northern New Zealand island, and those islands that are forested are dominated by angiosperms which are assumed to be climax forests. The pollen and DNA evidence for conifer- and palm-rich forests in the prehuman era challenge this climax forest assumption. Prehuman vegetation records can thus help to inform future restoration of degraded offshore islands by informing the likely rate and direction of successional change; helping to determine whether natural rates of succession are preferable to more costly replanting programs; and providing past species lists if restoration replanting is desired.

Human ancient and extant mtDNA from the Gambier Islands (French polynesia): Evidence for an early Melanesian maternal contribution and new perspectives into the settlement of Easternmost Polynesia

Molecular anthropology has been widely used to infer the origin and processes of the colonization of Polynesia. However, there are still a lack of representative geographical studies of Eastern Polynesia and unchallenged genetic data about ancient Polynesian people. The absence of both of these elements prevents an accurate description of the demographic processes of internal dispersion within the Polynesian triangle. This study provides a twofold analysis of ancient and modern mtDNA in the eastern part of French Polynesia: the Gambier Islands. The paleogenetic analyses conducted on burials of the Temoe Atoll (14(th) -17(th) centuries) represent the first fully authenticated ancient human sequences from Polynesia. The identification of the "Melanesian" Q1 mtDNA lineage in ancient human remains substantiates the Near Oceanic contribution to the early gene pool of this region. Modern samples originate from Mangareva Island. Genealogical investigations enable us to reliably identify the conservation of the Melanesian component in Easternmost Polynesia, despite recent European colonization. Finally, the identification of rare mutations in sequences belonging to haplogroup B4a1a1a provides new perspectives to the debate on the internal peopling of the Polynesian region. Altogether, the results laid out in our study put the emphasis on the necessity of controlled sampling when discussing the internal settlement of Polynesia.

Shear wave speed structure beneath the South Pacific superswell using broadband data from ocean floor and islands

We determined three‐dimensional shear wave speed structure beneath the South Pacific superswell down to a depth of 200 km by analyzing Rayleigh wave records from broadband ocean bottom seismograph stations and island stations in the Pacific Ocean. The ocean bottom stations were deployed from 2003 to 2005 on the seafloor in the French Polynesian region, which enabled us to study the upper mantle structure beneath the Superswell with unprecedentedly high resolution. We measured the dispersions of fundamental mode Rayleigh waves at periods between 40 and 140 seconds by the two‐station method. We found pronounced slow anomalies near the hot spots and in the Lau Basin. The slow anomalies beneath the hot spots have deeper‐rooted than those associated with the Lau basin. The slow anomalies near the Society, Macdonald, Marquesas, and Pitcairn hot spots continue down to at least 200 km depth.

Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin

To investigate the origin of the HIMU (high-μ) reservoir in the mantle, we measured Li, Sr, and Nd isotopic compositions of several oceanic island basalts (OIBs) from the Polynesian region. We used a recently developed multiple-collector inductively coupled plasma mass spectrometry method that allows precise and accurate Li isotopic determinations. This study presents the first Li isotopic data on HIMU OIBs. The measured whole-rock δ7Li values (δ7Li = [[7Li/6Li]sample/[7Li/6Li]L-SVEC standard - 1] × 1000) of the Polynesian HIMU OIBs (Mangaia, Tubuai, and Rurutu) range from +5.0‰ to +7.4‰, which are higher than those of fresh normal mid-ocean ridge basalt (N-MORB) glasses (ca. +3‰). The simultaneously measured K/Rb, Ba/Rb, and 87Sr/86Sr ratios indicate that the analyzed HIMU OIBs are free from significant posteruption alteration. These results suggest that the δ7Li value of the Polynesian HIMU source is never lower than those of the N-MORBs. Among the numerous models for the origin of the HIMU source, the most widely accepted model is that it involves subducted (dehydrated) oceanic crust. For this HIMU-origin model, our new Li isotopic results exclude the highly altered portion, that is, the uppermost part of the oceanic crust, because the δ7Li value of subducted highly altered MORB should be extremely low (δ7Li < fresh MORB). For these reasons, we propose that the Polynesian HIMU source is the relatively less-altered oceanic crust underlying the highly altered crust. Whereas Pb, Sr, and Nd isotopic signatures dominantly indicate the involvement of sediments in a source, the Li isotopic signature is more sensitive to the degree of alteration experienced by the basaltic crust and thus can be used to distinguish what part of the crust was trapped in the OIB magma. It therefore provides information complementary to that provided by the radiogenic isotopes.

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

AbstractAim 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.

THE LICHENS OF RAROTONGA, COOK ISLANDS, SOUTH PACIFIC OCEAN II: PARMELIACEAE

Ten parmelioid taxa in five genera were identified from Rarotonga, Cook Islands, South Pacific Ocean. These comprise: three species of Bulbothrix, one species of Canoparmelia, four species of Parmotrema, one species of Rimelia and one species of Xanthoparmelia. Canoparmelia rarotongensis Louwhoff & Elix is described as new, being distinguished from other species of this genus by its unique secondary chemistry (lecanoric acid) and conspicuous, inflated isidia. The majority of parmelioid lichens on Rarotonga have cosmopolitan and pantropical distributions.Bulbothrix is reported for the first time from the Polynesian region.

Noble gas study of HIMU and EM ocean island basalts in the Polynesian region

Noble gas isotopes of HIMU and EM ocean island basalts from the Cook-Austral and Society Islands were investigated to constrain their origins. Separated olivine and clinopyroxene (cpx) phenocrysts were used for noble gas analyses. Since samples are relatively old, obtained from the oceanic area and showing chemical zoning in cpx phenocrysts, several tests on sample preparation and gas extraction methods were performed. First, by comparing heating and crushing methods, it has been confirmed that the crushing method is suitable to obtain inherent magmatic noble gases without radiogenic and cosmogenic components which were yielded after eruption, especially for He and Ne analyses. Second, noble gas compositions in the core and the rim of cpx phenocrysts were measured to evaluate the zoning effect on noble gases. The result has been that noble gas concentrations and He and Ne isotope ratios are different between them. The enrichment of noble gases in the rim compared to the core is probably due to fractional crystallization. Difference of He and Ne isotope ratios is explained by cosmogenic effect, and isotope ratios of the trapped component seem to be similar between the rim and the core. Third, leaching test reveals no systematic differences in noble gas compositions between leached and unleached samples. 3He/ 4He ratios of HIMU samples in the Cook-Austral Islands are uniform irrespective of phenocryst type (olivine and cpx) and age of samples (10–18 Ma), and lower (average 6.8 R A) than those of the Pacific MORB. On the other hand, 3He/ 4He of EM samples in the Cook-Austral Islands are similar to MORB values. EM samples in the Society Islands show rather higher 3He/ 4He than MORB. Ne, Kr and Xe isotope ratios are almost atmospheric within analytical uncertainties. 40Ar/ 36Ar are not so high as those of MORB. Anomalous noble gas abundance pattern such as He and Ne depletion and Kr and Xe enrichment relative to atmospheric abundances was observed. Furthermore, Ne/Ar and Kr/Ar show correlation with some trace elemental ratios like La/Yb. Lower 3He/ 4He of HIMU than MORB values requires relatively high time-integrated (U + Th)/ 3He for the HIMU source, which suggests that the HIMU source was produced from recycled materials which had been once located near the Earth’s surface. Moreover, extreme noble gas abundance pattern and strong correlation of Ne/Ar and Kr/Ar with La/Yb indicate that the HIMU endmember is highly depleted in light noble gases and enriched in heavy noble gases. Such feature is not common to mantle materials and is rather similar to the noble gas abundance patterns of the old oceanic crust and sediment, which supports the model that the HIMU source originates from subducted oceanic crust and/or sediment. If the HIMU source corresponds to the oceanic crust which subducted at 1–2 Ga as suggested by Pb isotope studies, however, the characteristic 3He/ 4He of HIMU (6.8 R A) would be too high because radiogenic 4He produced by U and Th decay should dramatically decrease 3He/ 4He. To overcome this problem, the He open system model is introduced which includes the effects of 4He production and diffusion between the HIMU source material and the surrounding mantle. This model favors that the HIMU source resides in the upper mantle, rather than in the lower mantle. Furthermore, this model predicts the thickness of the HIMU source to be in the order of 1 km. In contrast to low and uniform 3He/ 4He character of HIMU, 3He/ 4He of EM are rather variable. Entrainment of upper mantle material and/or a less-degassed component are required to explain the observed 3He/ 4He of EM in the Polynesian area. Participation of the less-degassed component would be related to the “superplume” below the Polynesian region.

Pollutant pathways between Mururoa and other polynesian islands, based on numerical model trajectories

We address the question of which Polynesian islands would be most vulnerable to exposure from radio-nuclide material as a result of past nuclear testing at Mururoa and Fangataufa, should some of the material now stored in the atolls find its way into the ocean. We use an ocean circulation model of the Polynesian region with 26.5 km resolution and four open boundaries to find advective pathways from Mururoa to other islands. The model is driven by monthly mean wind stress and by the large-scale circulation determined from the wind stress curl at the northern and southern boundaries. Surface trajectories vary strongly with the seasons but always indicate southward or south-westward movement. Trajectories at 50 m and 100 m follow the South Equatorial Current westward. According to the model, no islands in the main island groups north of the latitude of Mururoa (22°S) are on a direct (advective) pathway with Mururoa or Fangataufa at any time. The islands most in danger of exposure to material from the two nuclear test sites are those in the Austral Group.

A Revised Checklist of Polynesian Benthic Marine Algae

A revised checklist of 425 taxa of benthic marine algae is provided for the French Polynesian region, including the Society Islands, Tuamotu Archipelago, Marquesas Islands and Austral Islands. The list comprises 117 Cyanophyceae, 42 Phaeophyceae, 96 Chlorophyceae and 170 Rhodophyceae, representing 79 new additions to the last checklist a decade earlier. Included are all previously published records and some yet unpublished additions, with the systematic arrangement and nomenclature updated. The flora of Tahiti and its adjacent islands is quite well known, whereas the one from Marquesas, Austral and Gambier Islands have yet to be adequately examined. Also, such algal groups as the crustose Corallinaceae are still poorly studied.

Lapitoid settlements of Futuna and Alofi, Western Polynesia

change in the Fiji-West Polynesian region, change due at least in part to adaptation to truly 'oceanic' environmental conditions (Green 1979; Kirch 1980), although we are still ignorant of the details of this transformation. Green (1978, 1979) has demonstrated that the Lapita Cultural Complex exhibits both spatial and temporal variability, and has convincingly distinguished major Western and Eastern subgroups. Within the Eastern subgroup (the Fiji-West Polynesian area) which concerns us here, there are only a handful of excavated, well-analyzed and published sites. The most important of these sites are: Natunuku, Yanuca, and Sigatoka in Fiji (Birks 1973; Hunt 1980); TO-2, Mangaia Mound, Vuki's Mound, and TO-6 on Tongatapu (McKera 1929; Poulsen 1968; Groube 1971); Lolokoka, Lotoa, and Pome'e on Niuatoputapu (Kirch 1978); and Ferry Berth, Sasoa'a, and Vailele on Upolu, Western Samoa (Green and Davidson 1969, 1974). To understand how Lapita colonizers diversified to become the cultures known historic-

A Stochastic Model of Ocean-Drift Migration

At this stage of the conference it seems a good idea to introduce some history, geography and perhaps a dash of anthropology. The historical content is concerned with the sixteenth and seventeenth centuries when European explorers 'discovered' the Pacific Ocean and found that almost all the habitable islands were or had been occupied. At first this may not seem very startling. But since then, anthropologists have established that the Pacific islands, typically thousands of miles from any continental coastline, were first inhabited about 3,000 years before Europeans had either the technology or the confidence to even attempt trans-oceanic voyages. So it is understandable that the question of the origins of the Pacific islanders has been a centre of debate among Europeans for several centuries. As one author has written '... the controversy has generated much heat, some light and innumerable papers, monographs and books.' Over the years the argument has developed, intensified and particularly centred on the settlement of Polynesia, the triangular region bounded by the Hawaiian Islands in the north, New Zealand in the south and Easter Island in the east (see Figure 1). Until half way through this century the most popular theories for the settlement of Polynesia suggested island-hopping routes from Asia via Melanesia or Micronesia. Any other route from a continent was considered impossible, due to the long ocean voyages involved. It was this attitude which faced Heyerdahl in the 1940's when he postulated the settlement of Polynesia by ocean-drift voyages from the Americas. His theory was not taken seriously until the famous Kon Tiki expedition, in which he sailed a balsa raft from Peru to the Tuomotu Archipelago, which is at about the centre of the Polynesian region. However, as Heyerdahl himself noted, although the Kon Tiki expedition established the plausibility of his theory it was not conclusive proof. In fact such a theory is impossible to prove-all one can do is build up evidence for or against it. That is, one aims to establish the probability of the theory. Levison, Ward and Webb (1973) set up a model for Monte Carlo simulation to estimate the probabilities of successful ocean-drift voyages to and between the islands of Polynesia. Their model had the advantage of simplicity, at least in concept, but suffered from the disadvantage of requiring a very large

Mayr on the Polynesian Region

[Borders and Subdivisions of the Polynesian Region, as based on our Knowledge of the Distribution of Birds, pp. 191–195. The Origin and History of the Bird fauna of Polynesia, pp. 197–216. By Ernst Mayr. Proc. Sixth Pacific Science Congress, held at Berkeley, Wis., in July and August 1939, vol. iv.]