The terrestrial Isopoda (Crustacea,Oniscidea) of Rapa Nui (Easter Island), with descriptions of two new species

Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered ‘disturbance relicts’ and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.     

Craniometric variation and homogeneity in prehistoric/protohistoric Rapa Nui (Easter Island) regional populations

Discrete cranial morphological traits of prehistoric/protohistoric Rapa Nui (Easter Island) inhabitants have been examined and have illustrated distinct regional or tribal differences; however, craniometric traits have not been as extensively evaluated to determine if similar regional population differences exist. This study examines the range of variability of Rapa Nui craniometrics and utilizes population genetic techniques to evaluate the level of homogeneity/heterogeneity within the island populations. The data consist of 50 cranio-facial measurements of Rapanui (Easter Islanders) skeletal material from the Late Prehistoric (1680-1722) and Protohistoric (1722-1868) periods. The sample was divided into five tribal regions: North, Northeast, South, Southwest, and West. General linear models (GLM) statistical analyses revealed one variable significant for males and 10 for females across tribal regions, totaling 11 regionally significant variables. Discriminant function analyses utilizing crossvalidation provided classification error rates of 55.8% males and 59.0% for females when utilizing those eleven significant variables. Minimum F(ST) values for males (0.06378) and females (0.09409) were calculated from unbiased Mahalanobis D(2) values. These values indicate that males have greater between-group homogeneity than females. The determinant ratio for the Northeast tribal region was the only significant ratio, yet all but one of the regional determinant ratios displayed a pattern of greater male than female mobility. These results indicate that significant craniometric differences between the tribal regions did not exist in prehistoric/protohistoric Rapa Nui populations, supporting the findings of previous research which has documented the homogeneity of the craniometrics of those tribal populations. The calculated minimum F(ST) values indicate the existence of different levels of heterogeneity between the male and female Rapa Nui regional populations resulting from differential levels of migration and gene flow. This variation reflects the establishment in prehistoric times of extensive tribal marriage tumus, and the existence of lineage endogamy/restricted exogamy, not the widespread practice of strict tribal endogamy.     

First sighting of a tropical benthic reef shark species at Rapa Nui: chance dispersal or a sign of things to come?

On 20 December 2017, a mature Triaenodon obesus was observed at Hanga Roa Bay, Rapa Nui (Easter Island) at c.18 m depth. This observation increases both the range of T. obesus in the Pacific Ocean and the number of elasmobranch species at Rapa Nui. In combination with other recent sightings further extending the southern range of this species during the Austral summer, sea surface temperature is suggested as key to southern dispersal.     

Inbreeding and surnames: a projection into Easter Island's past

The population of Easter Island is one of the most interesting extant human communities due to its unique demographic history, its geographic isolation, and the development of an incomparable culture characterized by the towering "Moais" and its enigmatic writing. Following the colonization of its population by Polynesians from the Mangarevan Islands in the 5th century AD, the island remained isolated up until the middle of the 20th century. Under these conditions, with endogamy levels fluctuating between 61.04-96.54% and given such a small population, a high rate of inbreeding, and consequently, an elevated level of genetic relationships would be expected. Using data from church and civil records, we calculated the consanguinity of the population of Rapa Nui. The results of this analysis do not support the hypothesis of a high level of consanguinity (alpha = 0.00028 and F(t) = 0.0007, with F(r) = 0.00586 and F(n) = -0.00519), suggesting instead the existence of a strategy used to avoid marriage between close relatives. To explain these observations, the structure and exchange dynamics of the population were studied in the tribes, known locally as "Mata." The results of this analysis suggest a tendency toward the avoidance of inbreeding within tribes, in order to decrease the rate of endogamy in each group. This is consistent with ethnographic observations from the beginning of the 20th century that support the existence of strict regulations to prevent inbreeding between closely related individuals. Furthermore, we confirm that this situation dates back to a period before the "refounding" of Easter Island. Our results demonstrate that conditions of geographical isolation are not in themselves sufficient to produce an elevated inbreeding coefficient, revealing Easter Island as an interesting example of how cultural rules can shape the genetic structure of a population.     

Linguistic Syncretism and Language Ideologies: Transforming Sociolinguistic Hierarchy on Rapa Nui (Easter Island)

Recent work in linguistic anthropology highlights the role of linguistic ideologies, or cultural conceptions of language, in transforming social relations and linguistic structure and use. This article examines the links between language attitudes and uses in their institutional and interactional contexts on Rapa Nui, a Polynesian island community that is part of the Chilean nation-state. By the 1970s, a sociolinguistic hierarchy and functional compartmentalization of languages between Spanish and Rapa Nui—what I will describe as "colonial diglossia"—had become established in the community, which was rapidly becoming bilingual. Language shift toward Spanish has continued to advance since then. However, rising Rapa Nui syncretic language practice and consciousness, combined with the political successes of a local indigenous movement and changes in the local economy, are now contributing to the breakdown of colonial diglossia, generating better conditions for the maintenance of the Rapa Nui language.     

A stable isotope (δ13C and δ15N) perspective on human diet on rapa nui (Easter Island) ca. AD 1400–1900

Ecological and environmental evidence suggests that Rapa Nui was among the most marginally habitable islands in Eastern Polynesia, with only a fraction of the biotic diversity found on archipelagos to the west, and capable of sustaining many fewer cultigens traditionally transported by Polynesian colonizers. However, archaeological evidence for human dietary adaptations under such restrictions is limited. Little is known about the particulars of the subsistence base and dietary changes on Rapa Nui that may be associated with a hypothesized late prehistoric decline in the quality and diversity of food sources. To better understand prehistoric Rapa Nui diet we examined stable carbon and nitrogen isotope compositions of human teeth along with archaeological faunal material thought to comprise the Rapa Nui food web. Our results indicate that contrary to previous zooarchaeological studies diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants. While a few individuals may have had access to higher trophic level marine resources, this is evident only later in time (generally post–AD 1600). A decline in δ¹⁵N through time was observed, and may be attributed to declines in available terrestrial proteins; however, presently we cannot rule out the effect of changing soil and plant baseline δ¹⁵N. Our results also suggest differential access to higher trophic level marine resources among contemporaneous populations, but more research is required to clarify this observation. Am J Phys Anthropol 152:173–185, 2013. © 2013 Wiley Periodicals, Inc.     

Coping with Pleistocene climatic fluctuations: Demographic responses in remote endemic reef fishes

Elucidating demographic history during the settlement of ecological communities is crucial for properly inferring the mechanisms that shape patterns of species diversity and their persistence through time. Here, we used genomic data and coalescent‐based approaches to elucidate for the first time the demographic dynamics associated with the settlement by endemic reef fish fauna of one of the most remote peripheral islands of the Pacific Ocean, Rapa Nui (Easter Island). We compared the demographic history of nine endemic species in order to explore their demographic responses to Pleistocene climatic fluctuations. We found that species endemic to Rapa Nui share a common demographic history, as signatures of population expansions were retrieved for almost all of the species studied here, and synchronous demographic expansions initiated during the last glacial period were recovered for more than half of the studied species. These results suggest that eustatic fluctuations associated with Milankovitch cycles have played a central role in species demographic histories and in the final stage of the community assembly of many Rapa Nui reef fishes. Specifically, sea level lowstands resulted in the maximum reef habitat extension for Rapa Nui endemic species; we discuss the potential role of seamounts in allowing endemic species to cope with Pleistocene climatic fluctuations, and we highlight the importance of local historical processes over regional ones. Overall, our results shed light on the mechanisms by which endemism arises and is maintained in peripheral reef fish fauna.     

Conservation of the extinct Toromiro Tree, Sophora toromiro

One of the extinct flowering plants of Easter Island (Rapa Nui) is the Toromiro Tree, Sophora toromiro Skottsb. (Leguminosae) which is, however, maintained in cultivation in several botanic gardens. An outline of the history of the flora of the island, and of the Toromiro in particular, are given. The efforts of the Toromiro Management Group to secure its future, and its successful re-introduction to the island, are described.     

Genetic diversity and pedigree for Sophora toromiro (Leguminosae): a tree extinct in the wild

Sophora toromiro was endemic to the Pacific island of Rapa Nui (Easter Island) and is extinct in the wild. The species has survived in private and botanic gardens. The species is the subject of an international study to support its conservation ex situ and eventual re-introduction. As a contribution to this study the genetic diversity of the surviving stocks and herbarium samples has been assessed by means of random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (inter-SSR) analysis. The analysis indicated low levels of genetic diversity suggesting a very small number of founders. In addition, misidentified trees were identified allowing their removal from the conservation project.     

Distribution of hereditary blood groups among Indians in South America. IV. In Chile with inferences concerning genetic connections between Polynesia and America

This is the fourth paper in a series on the distribution of blood groups among Indians of South America. It reports the findings on the Indians of Chile and the Polynesians of Chile's Easter Island. Blood specimens were procured from the following putatively pure Indians and unmixed Polynesians: 44 Alacaluf of Puerto Eden, Isla Wellington, 141 Mapuche (Araucanian) of Lonquimay, Malleco Province, 80 Atacameños of Antofagasta Province, and 45 Polynesians of Easter Island. These 310 samples were tested for blood factors in the A-B-O, M-N-S-s, P, Rh-Hr, Lutheran, K-k, Lewis, Duffy, Kidd and Diego systems, and for the Wright (Wr^a) agglutinogen. Serum samples were tested for haptoglobins and transferrins. Hemolysates prepared from the blood clots were tested for hemoglobin types. The results are presented as phenotype incidences and calculated gene frequencies in appropriate tables. Locations of the populations from which blood samples were procured are shown on two maps. The high frequencies for the O gene usually reported for South American Indians obtain in putatively pure Chilean Indians but A¹ is high in Easter Island Polynesians. In both Indians and Polynesians M, s, R¹ (CDe), R² (cDE), Lu^b, k, Le^H, and Fy^a gene frequencies are high and B, N, S, Mi^a, Vw, Rº (cDe), r (cde), Lu^a, K, Le¹, Fy^b, and Wr^a (Ca) are low or absent. The Diego (Di) gene is present in the Mapuche and Atacameños but absent in the Alacaluf and Polynesians. Hp¹ gene frequencies were determined only in the Alacaluf and Atacameños, in which they are 0.48 and 0.67 respectively. Transferrins were determined for the Alacaluf and Atacameños Indians and all were classified as Tf C. All Chilean Indian and Polynesian specimens were tested electrophoretically for hemoglobin types and all contained only hemoglobin (A) as a major component.     

NOTES ON THE BIRDS OF EASTER ISLAND

Information on the occurrence and breeding status of sea-birds at Easter Island has long been scanty and incomplete. In order to obtain accurate information and in particular to investigate reports of a supposed breeding site of a "brown-plumaged petrel", we spent three weeks on the island, including 12 days camping out on the uninhabited, waterless islet of Motu-Nui.
The petrel proved to be the Christmas Island Shearwater Puffinus nativitatis , whose breeding range is thus extended by nearly 2,000 miles. Ten other species of sea-birds were definitely identified and specimens, photographs and breeding records were obtained for most of them. It is shown that the bird species frequenting Easter Island are, like the human inhabitants, predominantly of Polynesian origin—in fact the American continents are not represented at all.
The paper opens with a brief outline of present-day conditions on the main island, and concludes with an account of the "bird-cult" rituals which are known to have been a feature of life in Easter Island for centuries.     

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.     

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.     

Polynesian ant (Hymenoptera: Formicidae) species richness and distribution: a regional survey

Thirteen Polynesian islands, including five true atolls, an uplifted atoll, and seven high volcanic islands of varying ages, were surveyed for ants by hand collecting techniques. Ten of the thirteen islands had been surveyed previously, and more and species were found in the present survey than were known from all earlier surveys combined, with two exception (Ducie Atoll and Easter Island).This represents the first report of the Argentine ant, Linepithema humile Mayr, from Easter Island. L. humile is a very successful pest species which has only recently invaded Easter Island, and is now very abundant and widespread, occurring at 16 of the 17 sample sites scattered across the island. The introduction of this species is almost certainly responsible for the apparent decline in species richness on Easter Island.In general, more species were present on high islands than atolls of a similar size, and elevation was significant while log (area) and latitude were not in a multiple linear regression with ant species number as the dependent variable. Not enough time was spent on the islands to survey their ant faunas completely, and extrapolations from species effort curves and jackknife estimators of earlier, thorough surverys for ants in the society Islands suggest that only about 50% of the total species were collected in the present survey, at least on the high islands. My collections were probably more complete on the atolls. The increase in species numbers from the present survey relative to known species richnesses (particularly when a large fraction of the species actually present were probably not included in the present survey) supports the hypothesis that remote Polynesian islands are not as depauperate in terms of ant species numbers as previously thought.     

Statistical measures of intrasample variability

We have implemented a multivariate statistical methodology to assess the degree and pattern of variability in skeletal samples. Specifically, it is designed to test whether variability in a skeletal sample exceeds that of a local breeding population, defined in the present instance as variability present among crania from an endogamous village. It involves the use of covariance matrices derived from hypothesis and reference samples. The methodology has been applied to subsamples of a Plains Indian craniometric database consisting of 80 variables taken on some 1000 individuals. The subsamples are assumed to reflect varying patterns and degrees of intrasample variability. The assumed group structures are assembled posthoc and subject to various analyses. The excellent results attest to the great potential of the methodology.     

Differential skeletal preservation at Windover Pond: causes and consequences

In this paper, we evaluate the causes of differential skeletal preservation in the Windover Pond skeletal series (8BR246). We collected data on sex and age for approximately 110 individuals, and calculated a preservation score for each individual based on the presence of 80 skeletal landmarks. Our research questions evaluated the relationship between bone preservation and individual age and sex, and between the presence of preserved brain material and skeletal preservation, and the effects of burial location on bone preservation. The results indicate variability in average preservation for the sample (micro = 0.53, SD = 0.22) with an apparent lack of sex-specific (P = 0.79) or age-specific (P = 0.37) differences in preservation. The relationship between brain and skeletal preservation (P = 0.15) was not significant. The horizontal distribution of burials was not significantly correlated with skeletal preservation (north: r = -0.10, P = 0.93; east: r = 0.09, P = 0.45); however, vertical depth was a significant predictor of preservation (r = -0.31, P = 0.005), indicating that skeletal preservation decreased as burials were located closer to the ground surface. The observed variability in preservation scores may be related to the partial drying and resubmergence of the uppermost burials for the last few millennia. Comparison of Windover element-specific survival rates with previous analyses based on terrestrial samples (Galloway et al. [1997] Forensic taphonomy, Boca Raton: CRC Press; Waldron [1987] Death, decay and reconstruction, Manchester: Manchester University Press; Willey et al. [1997] Am J Phys Anthropol 104:513-528) affirms the relationship between element weight or density and bone survival. The unique taphonomic context of our study sample effected little change in bone deterioration processes.     

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.     

The cranial morphology of the Botocudo Indians,Brazil

The Botocudo Indians were hunter‐gatherer groups that occupied the East‐Central regions of Brazil decimated during the colonial period in the country. During the 19th century, craniometric studies suggested that the Botocudo resembled more the Paleoamerican population of Lagoa Santa than typical Native Americans groups. These results suggest that the Botocudo Indians might represent a population that retained the biological characteristics of early groups of the continent, remaining largely isolated from groups that gave origin to the modern Native South American variation. Moreover, recently, some of the Botocudo remains have been shown to have mitochondrial and autosomal DNA lineages currently found in Polynesian populations. Here, we explore the morphological affinities of Botocudo skulls within a worldwide context. Distinct multivariate analyses based on 32 craniometric variables show that 1) the two individuals with Polynesian DNA sequences have morphological characteristics that fall within the Polynesian and Botocudo variation, making their assignation as Native American specimens problematic, and 2) there are high morphological affinities between Botocudo, Early Americans, and the Polynesian series of Easter Island, which support the early observations that the Botocudo can be seen as retaining the Paleoamerican morphology, particularly when the neurocranium is considered. Although these results do not elucidate the origin of the Polynesian DNA lineages among the Botocudo, they support the hypothesis that the Botocudo represent a case of late survival of ancient Paleoamerican populations, retaining the morphological characteristics of ancestral Late Pleistocene populations from Asia. Am J Phys Anthropol 157:202–216, 2015. © 2015 Wiley Periodicals, Inc.     

Craniofacial affinities of Mariana Islanders and Circum-Pacific peoples

Metric craniofacial variation was studied in a number of skeletal samples that originated from the Mariana Islands and circum-Pacific regions. The broad comparisons including East/Southeast Asians, Polynesians, Melanesians, and Australians confirm the relationships between Mariana Islanders and East/Southeast Asians on the one hand and Polynesians on the other hand. A transformation of Melanesians into western Micronesians is not supported. The result of the principal component analysis indicates that the cranial morphological pattern of Mariana people shares the intermediate characteristics between those of typical East/Southeast Asians and several groups falling as outliers to more predominant Asian populations. Am J Phys Anthropol 104:411–425, 1997. © 1997 Wiley-Liss, Inc.     

Migration and isolation effects on the Rapanui population (Easter island) through the analysis of STRs on the Y chromosome

Cultural and biological data suggests the Polynesian origin of the Rapanui population, although the presence of foreign genes in the native population, as a result of admixture with Europeans in the last two centuries has also to be considered. In order to estimate the genetic affinities of the present-day inhabitants of Easter Island and the nearby populations, we used seven polymorphisms of the Y chromosome. However we want to estimate the grade of admixture on the genetic structure that was brought from foreigners within the last two centuries upon the more geographically isolated populations in the world. The preliminary results showed the presence of 18 haplotypes analyzed on 30 male samples. The analysis of the allelic frequency showed a distribution typical of the Polynesian populations. Available data in literature, even with some differences probably due to either the founder effect or historical and ecological events that created sudden demographic variations on the island population. The phylogentic analysis of the haplotypes obtained through Network Median Joining showed two different cluster of haplotypes, of which one represents about 64% of the present haplotypes on Easter Island, which are characterized from the presence of the allele DYS19^*16, very frequent in the Pacific populations. The other cluster is characterized from the presence of the allele DYS19^*14, absent within the populations in the Pacific and with reasonable high frequency within the European populations and South American. Most probably the two clusters are the product of several colonizations that Easter Island had endured from the time of the Chilian and European Colonies. It was demonstrated in fact, that the arrival in 1914 of 50 German and English prisoners would have left a considerable genetic impact on the population of Rapanui, which during this period was of small size.