Bird remains from an archaeological site on Henderson Island, South Pacific: Man-caused extinctions on an "uninhabited" island

A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia

We describe a new species of Polynesian sandpiper from Henderson Island, Prosobonia sauli sp. nov., based on multiple Holocene fossil bones collected during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991–92). Prosobonia sauli is the only species of Prosobonia to be described from bone accumulations and extends the record of known extinct Polynesian sandpipers to four. It is readily differentiated from the extant Tuamotu Sandpiper P. parvirostris in several features of the legs and bill, implying ecological adaptations to different environments. The geographically nearest Prosobonia populations to Henderson Island were found on Mangareva, where it is now extinct. A previous record of a species of Prosobonia from Tubuai, Austral Islands, is here shown to belong to the Sanderling Calidris alba. Our analyses of newly sequenced genetic data, which include the mitochondrial genomes of P. parvirostris and the extinct Tahiti Sandpiper P. leucoptera, confidently resolve the position of Prosobonia as sister-taxon to turnstones and calidrine sandpipers. We present a hypothesis for the timing of divergence between species of Prosobonia and other scolopacid lineages. Our results further provide a framework to interpret the evolution of sedentary lineages within the normally highly migratory Scolopacidae.

BODY SIZE OF INSULAR LIZARDS: A PATTERN OF HOLOCENE DWARFISM

Until recently there have been scant historical data available to test and supplement studies on the evolution of body size within insular lizards. However, there is now an accumulating fossil record from islands which shows that numerous species have declined in average maximum body size since the beginning of the Holocene, regardless of phylogenetic afffinities, habits, or even size of the species itself. Coincident with decline in body size, human colonization of islands has permanently altered insular environments, with the consequence that native flora and fauna have been depleted. Indeed, the fossil record documents high extinction rates among insular vertebrates during the past few thousand years. It follows that resource deterioration may have led to the reduction of lizard body size, as expressed genotypically in selection for corresponding smaller dimensions, and phenotypically through arrested growth and development leading to compression of the age-class structure. The effect of human settlement on small islands has been underestimated, and although the consequences do not render completely in vain the attempts to understand ecological processes on them, they are of sufficient magnitude to stress caution in any assessment of a modern insular biota.

The evolutionary roots of our environmental problems: toward a Darwinian ecology

It is widely acknowledged that we need to stabilize population growth and reduce our environmental impact; however, there is little consensus about how we might achieve these changes. Here I show how evolutionary analyses of human behavior provide important, though generally ignored, insights into our environmental problems. First, I review increasing evidence that Homo sapiens has a long history of causing ecological problems. This means that, contrary to popular belief, our species' capacity for ecological destruction is not simply due to "Western" culture. Second, I provide an overview of how evolutionary research can help to understand why humans are ecologically destructive, including the reasons why people often overpopulate, overconsume, exhaust common-pool resources, discount the future, and respond maladaptively to modern environmental hazards. Evolutionary approaches not only explain our darker sides, they also provide insights into why people cherish plants and animals and often support environmental and conservation efforts (e.g., Wilson's "biophilia hypothesis"). Third, I show how evolutionary analyses of human behavior offer practical implications for environmental policy, education, and activism. I suggest that education is necessary but insufficient because people also need incentives. Individual incentives are likely to be the most effective, but these include much more than narrow economic interests (e.g., they include one's reputation in society). Moralizing and other forms of social pressure used by environmentalists to bring about change appear to be effective, but this idea needs more research. Finally, I suggest that integrating evolutionary perspectives into the environmental sciences will help to break down the artificial barriers that continue to divide the biological and social sciences, which unfortunately obstruct our ability to understand ourselves and effectively address our environmental problems.

A phylogenetic analysis of the Gruiformes (Aves) based on morphological characters, with an emphasis on the rails (Rallidae)

The order Gruiformes, for which even familial composition remains controversial, is perhaps the least well understood avian order from a phylogenetic perspective. The history of the systematics of the order is presented, and the ecological and biogeographic characteristics of its members are summarized. Using cladistic techniques, phylogenetic relationships among fossil and modern genera of the Gruiformes were estimated based on 381 primarily osteological characters; relationships among modern species of Grues (Psophiidae, Aramidae, Gruidae, Heliornithidae and Rallidae) were assessed based on these characters augmented by 189 characters of the definitive integument. A strict consensus tree for 20,000 shortest trees compiled for the matrix of gruiform genera (length = 967, CI = 0.517) revealed a number of nodes common to the solution set, many of which were robust to bootstrapping and had substantial support (Bremer) indices. Robust nodes included those supporting: a sister relationship between the Pedionomidae and Turnicidae; monophyly of the Gruiformes exclusive of the Pedionomidae and Turnicidae; a sister relationship between the Cariamidae and Phorusrhacoidea; a sister relationship between a clade comprisingEurypygaandMesselornisand one comprisingRhynochetosandAptornis; monophyly of the Grues (Psophiidae, Aramidae, Gruidae, Heliornithidae and Rallidae); monophyly of a clade (Gruoidea) comprising (in order of increasingly close relationship)Psophia,Aramus,Balearicaand other Gruidae, with monophyly of each member in this series confirmed; a sister relationship between the Heliornithidae and Rallidae; and monophyly of the Rallidae exclusive ofHimantornis. Autapomorphic divergence was comparatively high forPedionomus,Eurypyga,Psophia,HimantornisandFulica; extreme autapomorphy, much of which is unique for the order, characterized the extinct, flightlessAptornis.

In the species–level analysis of modern Grues, special efforts were made to limit the analytical impacts of homoplasy related to flightlessness in a number of rallid lineages. A strict consensus tree of 20,000 shortest trees compiled (length = 1232, CI = 0.463) confirmed the interfamilial relationships resolved in the ordinal analysis and established a number of other, variably supported groups within the Rallidae. Groupings within the Rallidae included: monophyly of Rallidae exclusive ofHimantornisand a clade comprisingPorphyrio(includingNotornis) andPorphyrula; a poorly resolved, basal group of genera includingGymnocrex,Habroptila,Eulabeornis,Aramides,CanirallusandMentocrex; an intermediate grade comprisingAnurolimnas,Amaurolimnas, andRougetius; monophyly of two major subdivisions of remaining rallids, one comprisingRallina(paraphyletic),Rallicula, andSarothrura, and the other comprising the apparently paraphyletic ‘long–billed’ rails (e.g.Pardirallus,Cyanolimnas,Rallus,GallirallusandCabalusand a variably resolved clade comprising ‘crakes’ (e.g.Atlantisia,LaterallusandPorzana, waterhens (Amaurornis), moorhens (Gallinulaand allied genera) and coots (Fulica). Relationships among ‘crakes’ remain poorly resolved;Laterallusmay be paraphyletic, andPorzanais evidently polyphyletic and poses substantial challenges for reconciliation with current taxonomy. Relationships among the species of waterhens, moorhens and coots, however, were comparatively well resolved, and exhaustive, fine–scale analyses of several genera (Grus,Porphyrio,Aramides,Rallus,LaterallusandFulica) and species complexes (Porphyrio porphyrio–group,Gallirallus philippensis–group andFulica americana–group) revealed additional topological likelihoods. Many nodes shared by a majority of the shortest trees under equal weighting were common to all shortest trees found following one or two iterations of successive weighting of characters. Provisional placements of selected subfossil rallids (e.g.Diaphorapteryx,AphanapteryxandCapellirallus) were based on separate heuristic searches using the strict consensus tree for modern rallids as a backbone constraint.

These analyses were considered with respect to assessments of robustness, homoplasy related to flightlessness, challenges and importance of fossils in cladistic analysis, previously published studies and biogeography, and an annotated phylogenetic classification of the Gruiformes is proposed.

Impact of early Polynesian occupation on the land snail fauna of Henderson Island, Pitcairn group (South Pacific)

Henderson Island, an uninhabited raised coral atoll in the Pitcairn group, has recently been designated a World Heritage Site because of its unique and relatively undisturbed ecosystem. The island is believed to have been uplifted and subaerially exposed during the last 275 kyr. This therefore provides the maximum age for the terrestrial biota that includes several endemic taxa. Henderson today supports 16 strictly terrestrial species of snails, about half of which are endemic. Analyses of sediments beneath Polynesian occupation horizons dated between the 11th and 17th centuries AD, have yielded 11 species of land snail present in the modern fauna, together with at least six (and possibly as many as eight) further species that no longer occur on the island. These extinct taxa are illustrated and formal descriptions provided for five ( Pleuropoma hendersoni , Orobophana carinacosta , Minidonta macromphalus , Philonesia pyramidalis , P. weisleri ); a sixth, known only from broken shells, appears to belong to the genus Hiona . The two remaining taxa are ‘tornatellinids’ that have not been recognized among the modern fauna. Radiocarbon dates from bones of associated extinct land birds confirm their occurrence on Henderson before the first signs of Polynesian settlement. The extinction of these taxa seems to coincide with the Polynesian occupation and evidence for large-scale burning, at least around parts of the plateau margin, suggests that their demise can be linked with habitat destruction. At least three species, Gastrocopta pediculus , Lamellidea oblonga and Pupisoma orcula , first appear in Polynesian occupation horizons. Their status as prehistoric introductions is therefore confirmed but G. pediculus no longer lives on Henderson. Pacificella variabilis , Tornatellides oblongus parvulus and Elasmias sp., all previously thought to have been other prehistoric introductions to Henderson, were recovered from pre-Polynesian levels and are therefore native.

Flightlessness and phylogeny amongst endemic rails (Aves:Rallidae) of the New Zealand region

The phylogenetic relationships of a number of flightless and volant rails have been investigated using mtDNA sequence data. The third domain of the small ribosomal subunit (12S) has been sequenced for 22 taxa, and part of the 5' end of the cytochrome-b gene has been sequenced for 12 taxa. Additional sequences were obtained from outgroup taxa, two species of jacana, sarus crane, spur-winged plover and kagu. Extinct rails were investigated using DNA extracted from subfossil bones, and in cases where fresh material could not be obtained from other extant taxa, feathers and museum skins were used as sources of DNA. Phylogenetic trees produced from these data have topologies that are, in general, consistent with data from DNA-DNA hybridization studies and recent interpretations based on morphology. Gallinula chloropus moorhen) groups basally with Fulica (coots), Amaurornis (= Megacrex) ineptus falls within the Gallirallus/Rallus group, and Gallinula (= Porphyrula) martinica is basal to Porphyrio (swamphens) and should probably be placed in that genus. Subspecies of Porphyrio porphyrio are paraphyletic with respect to Porphyrio mantelli (takahe). The Northern Hemisphere Rallus aquaticus is basal to the south-western Pacific Rallus (or Gallirallus) group. The flightless Rallus philippensis dieffenbachii is close to Rallus modestus and distinct from the volant Rallus philippensis, and is evidently a separate species. Porzana (crakes) appears to be more closely associated with Porphyrio than Rallus. Deep relationships among the rails remain poorly resolved. Rhynochetus jubatus (kagu) is closer to the cranes than the rails in this analysis. Genetic distances between flightless rails and their volant counterparts varied considerably with observed 12S sequence distances, ranging from 0.3% (Porphyrio porphyrio melanotus and P. mantelli mantelli) to 7.6% (Rallus modestus and Rallus philippensis). This may be taken as an indication of the rapidity with which flightlessness can evolve, and of the persistence of flightless taxa. Genetic data supported the notion that flightless taxa were independently derived, sometimes from similar colonizing ancestors. The morphology of flightless rails is apparently frequently dominated by evolutionary parallelism although similarity of external appearance is not an indication of the extent of genetic divergence. In some cases taxa that are genetically close are morphologically distinct from one another (e.g. Rallus (philippensis) dieffenbachii and R. modestus), whilst some morphologically similar taxa are evidently independently derived (e.g. Porphyio mantelli hochstetteri and P.m. mantelli).

Prehistoric Extinctions of Pacific Island Birds: Biodiversity Meets Zooarchaeology

On tropical Pacific islands, a human-caused "biodiversity crisis" began thousands of years ago and has nearly run its course. Bones identified from archaeological sites show that most species of land birds and populations of seabirds on those islands were exterminated by prehistoric human activities. The loss of birdlife in the tropical Pacific may exceed 2000 species (a majority of which were species of flightless rails) and thus represents a 20 percent worldwide reduction in the number of species of birds. The current global extinction crisis therefore has historic precedent.

Biogeography of Tongan birds before and after human impact

Bones deposited in caves show that, before the arrival of humans, at least 27 species of land birds lived on the Tongan island of 'Eua, where 13 indigenous species live today. Six of these 13 species were recorded from pre-human strata; three others probably occurred on 'Eua in pre-human times but were not in the fossil sample; and four others probably colonized 'Eua since the arrival of humans approximately 3000 years ago. Of the 23 species of extinct or extirpated land birds recorded from 'Eua, the nearest geographic occurrences of conspecifics or most closely related congeners are from the Solomon Islands (1 species), New Caledonia (2 species), Fiji and/or Samoa (9 species), elsewhere in Tonga (8 species), or unknown (3 species). The avifauna of West Polynesia (Fiji-Tonga-Samoa) is more closely related to that of Melanesia than that of East Polynesia. There was little pre-human turnover in Tongan land birds. The arrival of humans has influenced the Tongan avifauna more than any climatic, tectonic, or biological event of the past approximately 100,000 years.

Radiocarbon dates on bones of extinct birds from Hawaii

Bones from a stratified sedimentary deposit in the Puu Naio Cave site on Maui, Hawaiian Islands, reveal the late Holocene extinction of 19 species of birds. The age of the sediment and associated fauna was determined by direct radiocarbon dating (tandem particle accelerator-mass spectrometer; TAMS) of amino acids extracted from bones weighing as little as 450 mg. The 14C dates indicate that sediment has been accumulating in the lava tube for at least the last 7750 years, a suitable time frame for testing the hypothesis that Holocene extinction on islands began after human colonization. Despite growing evidence that a worldwide wave of extinctions coincided with human colonization of oceanic islands, little radiometric data have been available to date the extinction of most small fossil vertebrates on islands. The TAMS technique of dating purified collagen from the bones of small vertebrates could lead to vastly improved chronologies of extinction for oceanic islands where catastrophic mid- to late-Holocene extinction is expected or known to have occurred. Chronologies derived from nonarcheological sites that show continuous sedimentation, such as the Puu Naio Cave deposit, may also yield key evidence on the timing of earliest human settlement of Oceania.