Rainforests Of New Guinea Research Articles

Birds and bats reduce herbivory damage in Papua New Guinean highland forests.

Insectivorous predators, including birds and bats, play crucial roles in trophic cascades. However, previous research on these cascades has often relied on permanent predator exclosures, which prevent the isolation of specific effects of birds and bats, given their different activity patterns throughout the day. Moreover, limited knowledge exists regarding the variations in individual effects of these predators under different biotic and abiotic conditions, such as changes in elevation. To address these uncertainties, our study aimed to investigate the distinct effects of bats and birds on arthropod densities in foliage and herbivory damage in lowland and highland rainforests of Papua New Guinea (PNG). Predator exclosures were established for one month to exclude diurnal or nocturnal predators across 120 saplings (ca. 2.5-4 m tall) selected from two lowland and two highland forests (i.e., 30 saplings per study site) along the Mt. Wilhelm transect in PNG. Arthropods were collected and measured, and herbivory damage was analyzed at the end of the experiment. Birds significantly reduced arthropod densities by 30%, particularly in arthropods longer than 10 mm, regardless of elevation. Additionally, both birds and bats appeared to mitigate herbivory damage in highland forests, with protected saplings displaying up to 189% more herbivory. Our results support previous studies that have demonstrated the ability of insectivorous predators to reduce leaf damage through the control of arthropods. Furthermore, our approach highlights the importance and necessity of further research on the role of seasons and elevations in trophic cascades.

Systematics and palaeobiology of kangaroos of the late Cenozoic genus Protemnodon (Marsupialia, Macropodidae)

Species of the kangaroo genus Protemnodon were common members of late Cenozoic communities across Australia and New Guinea until their extinction in the late Pleistocene. However, since the genus was first raised 150 years ago, it has proven difficult to diagnose, as have the species allocated to it. This is due primarily to the incompleteness of the type material and a heavy reliance on cheek tooth size and slight variations in premolar form. Along with the rare association between cranial and postcranial material, this has hampered understanding of the palaeobiology of these large-bodied kangaroos. Here we review and re-diagnose Protemnodon, recognising a total of seven species and providing a hypothesis of species interrelationships. The following new synonymies are made: Protemnodon chinchillaensis is synonymised with P. otibandus and P. hopei with P. tumbuna. The following are considered nomina dubia: Protemnodon brehus, P. roechus, P. mimas, P. antaeus, and P. devisi. We reveal that the morphology of the cheek dentition is not as consistently useful for differentiating species of Protemnodon as features of the cranium and postcranial skeleton. As a whole, the species share anatomical features that reflect stability and power in the limb joints, yet they differ in body proportions, and axial and limb morphology. This we interpret as showing locomotory adaptations to different habitats. Of the three Pliocene species, Protemnodon snewini is interpreted as a medium- to high-geared hopper, suggesting proficiency in more open environments, whereas P. dawsonae sp. nov. we infer to have been a medium-geared inhabitant of eastern Australian forests and woodlands. Protemnodon otibandus, with a range extending through the woodlands and forests of eastern Australia into the rainforests of eastern New Guinea, displays adaptations to slower hopping. Its Pleistocene descendant, P. tumbuna, is convergent on the morphology of modern New Guinea forest wallabies, and was likely facultatively quadrupedal. Of the three Australian Pleistocene species, the long-necked P. anak is hypothesised to have been a large, medium-geared, eastern Australian species, and P. mamkurra sp. nov. a robust, low-geared resident of well-wooded southern Australia habitats. By contrast, P. viator sp. nov. was larger but more gracile, suggested to be a medium- to high-geared species convergent in some traits on large extant kangaroos. This and a wide inland distribution point to adeptness in open, arid environments. Protemnodon mamkurra sp. nov. and P. viator sp. nov. occupy the morphospace previously occupied by P. roechus and P. brehus. Overall, the species of Protemnodon exhibit a degree of ecomorphological variation suggestive of a broader array of ecological adaptations than hitherto envisioned.

Forest disturbance increases functional diversity but decreases phylogenetic diversity of an arboreal tropical ant community.

Tropical rainforest trees host a diverse arthropod fauna that can be characterised by their functional diversity (FD) and phylogenetic diversity (PD). Human disturbance degrades tropical forests, often coinciding with species invasion and altered assembly that leads to a decrease in FD and PD. Tree canopies are thought to be particularly vulnerable, but rarely investigated. Here, we studied the effects of forest disturbance on an ecologically important invertebrate group, the ants, in a lowland rainforest in New Guinea. We compared an early successional disturbed plot (secondary forest) to an old-growth plot (primary forest) by exhaustively sampling their ant communities in a total of 852 trees. We expected that for each tree community (1) disturbance would decrease FD and PD in tree-dwelling ants, mediated through species invasion. (2) Disturbance would decrease ant trait variation due to a more homogeneous environment. (3) The main drivers behind these changes would be different contributions of true tree-nesting species and visiting species. We calculated FD and PD based on a species-level phylogeny and 10 ecomorphological traits. Furthermore, we assessed by data exclusion the influence of species, which were not nesting in individual trees (visitors) or only nesting species (nesters), and of non-native species on FD and PD. Primary forests had higher ant species richness and PD than secondary forest. However, we consistently found increased FD in secondary forest. This pattern was robust even if we decoupled functional and phylogenetic signals, or if non-native ant species were excluded from the data. Visitors did not contribute strongly to FD, but they increased PD and their community weighted trait means often varied from nesters. Moreover, all community-weighted trait means changed after forest disturbance. Our finding of contradictory FD and PD patterns highlights the importance of integrative measures of diversity. Our results indicate that the tree community trait diversity is not negatively affected, but possibly even enhanced by disturbance. Therefore, the functional diversity of arboreal ants is relatively robust when compared between old-growth and young trees. However, further study with higher plot-replication is necessary to solidify and generalise our findings.

Soil fauna bioturbation along a successional gradient following swidden agriculture in the lowland tropical rainforests of New Guinea

Mesocosm studies in temperate soils indicate that soil fauna may promote accumulation of C in mineral soil. To test if this effect apply also in tropics we used field mesocosms that were either accessible or inaccessible to soil fauna. To explore potential interaction with traditional land use we locate these mesocosms along a succession gradient following traditional swidden agriculture in the lowland tropical rain forest of Papua New Guinea.Soil fauna densities did not show any significant changes along the succession gradient. Litter fall in primary forest was significantly higher than in younger succession stages. Litter stock on the soil surface follows the same pattern as litter fall. Litter stock was a few percent higher than annual litter fall suggests that litter removal from soil surface takes slightly over one year. Our Mesocosm experiment shows the same speed of litter removal (about one year). Litter removal from surface and its incorporation of organic matter into mineral soil is faster in the fauna treatment compared to the non-fauna treatment. Overall loss of C from the system was higher when fauna was absent.Fauna reduced overall loss of C from the soil in average for more then 40%. In conclusion soil fauna play important role in organic matter transformation and soil C storage in tropical ecosystem. Fauna removal substantially reduce overall soil C storage.

Satellite tracking resident songbirds in tropical forests.

Advances in tracking technology have helped elucidate the movements of the planet's largest and most mobile species, but these animals do not represent faunal diversity as a whole. Tracking a more diverse array of animal species will enable testing of broad ecological and evolutionary hypotheses and aid conservation efforts. Small and sedentary species of the tropics make up a huge part of earth's animal diversity and are therefore key to this endeavor. Here, we investigated whether modern satellite tracking is a viable means for measuring the fine-scale movement patterns of such animals. We fitted five-gram solar-powered transmitters to resident songbirds in the rainforests of New Guinea, and analyzed transmission data collected over four years to evaluate movement detection and performance over time. Based upon the distribution of location fixes, and an observed home range shift by one individual, there is excellent potential to detect small movements of a few kilometers. The method also has clear limitations: total transmission periods were often short and punctuated by lapses; precision and accuracy of location fixes was limited and variable between study sites. However, impending reductions in transmitter size and price will alleviate many issues, further expanding options for tracking earth's faunal diversity.

Re‐evaluating the evidence for late‐surviving megafauna at Nombe rockshelter in the New Guinea highlands

AbstractThe causes of the Late Pleistocene extinction of most larger‐bodied animals on the Australian continent have long been controversial. This is due, in no small part, to inadequate knowledge of exactly when these species were lost from different ecosystems. The Nombe rockshelter in the highlands of Papua New Guinea is one of very few sites on Sahul with as‐yet‐unrefuted evidence for the survival of megafaunal species until more recently than 40 thousand years (ka) ago. However, our understanding of the age of this site has been based on radiocarbon dating. Here we present new U–Th ages on large marsupial specimens from the deposit and identify a range of postcranial elements to species that include the diprotodontid Hulitherium tomasettii, kangaroo Protemnodon tumbuna and thylacine Thylacinus cynocephalus. Direct U–Th ages of 27–22 ka ago on faunal remains of Protemnodon tumbuna and another large unidentified macropodid are consistent with the existing radiocarbon chronology, yet are minimum ages due to the potential for post‐depositional uptake of 238U and stratigraphic reworking. Pollen analyses indicate perhumid, montane forests dominated by Nothofagus persisted, with minimal human disturbance from at least c.26–20 ka ago up to the terminal Pleistocene. Collagen fingerprinting (ZooMS) demonstrates the potential of protein‐based identification of megafaunal remains at Nombe in the future. This study leaves open the possibility of extended coexistence between some megafaunal species in the montane rainforests of New Guinea and intermittently visiting groups of people, and underscores the need for further investigation of the Nombe deposit. Although preliminary, these findings reinforce the view that debates regarding megafaunal extinctions on Sahul require a greater appreciation of species‐specific temporalities and the degrees of human impact on diverse habitats across the continent.

Day Time Activity Budgets, Height Utilization and Husbandry of Two Zoo-Housed Goodfellow’s Tree Kangaroos (Dendrolagus goodfellowi buergersi)

Goodfellow’s tree kangaroos (Dendrolagus goodfellowi) are an endangered, arboreal macropod native to the lower, mid-montane rainforests of Papua New Guinea. Despite a number of holders keeping D. goodfellowi in zoos across the world, there is a lack of recent published work on this species. Here, we present daytime activity budgets, document height use and provide husbandry information for two Goodfellow’s tree kangaroos (Dendrolagus goodfellowi buergersi) housed at Chester Zoo, UK. Throughout the observation period, both individuals spent the majority of their time resting within the environment but also spent time engaging in vigilance, travel and feeding behaviour. Additionally, despite the age and sex differences of the study individuals, both animals used the highest height level in the indoor habitat most frequently. We aim to share our information and encourage knowledge transfer with other holders, to both increase understanding and promote evidence-based management of this species.

Assemblages of fruit flies (Diptera: Tephritidae) along an elevational gradient in the rainforests of Papua New Guinea

Abstract Papua New Guinea (PNG) has the greatest diversity of dacine fruit fly species (Diptera: Tephritidae: Dacinae) in the world, many of which are significant agricultural pests. Although their taxonomy is relatively well known, there is limited research on their geographical and elevational distribution. We undertook a survey of PNG's fruit fly fauna along a complete elevational gradient on Mt Wilhelm (175–3700 m a.s.l.) to determine the elevational species distribution and turnover of fruit fly communities. Fruit flies were sampled using a selection of male parapheromone lures, including Zingerone, a new and promising male attractant. In total, we collected 10 700 fruit flies representing 77 species. The total abundance and species richness of fruit flies decreased with increasing elevation. Species richness was similarly high at 175 and 200 m a.s.l. (30 and 27 species) and at 700 and 1200 m a.s.l. (16 and 20 species, respectively) but dropped suddenly to only two species at 1700 m a.s.l. and to zero at all four sites above this elevation. There were no flies attracted exclusively to Zingerone. One species (Bactrocera recurrens) exhibited dramatic, temporal changes in abundance during the study period. Fruit fly assemblages were significantly influenced by both the lure type and elevation. Similarity of fruit fly communities decayed linearly with increasing elevational distance. We concluded that the upper limit of fruit fly distribution in PNG occurs between 1700 and 2200 m a.s.l. and the centre of diversity occurs between 0 and 700 m a.s.l.

Health service needs and perspectives of remote forest communities in Papua New Guinea: study protocol for combined clinical and rapid anthropological assessments with parallel treatment of urgent cases

IntroductionOur project follows community requests for health service incorporation into conservation collaborations in the rainforests of Papua New Guinea (PNG). This protocol is for health needs assessments, our first step...

Rationale, experience and ethical considerations underpinning integrated actions to further global goals for health and land biodiversity in Papua New Guinea

The SURFACES project is integrating action on good health and wellbeing [Sustainable Development Goal (SDG) 3] and conservation of life on land (SDG 15) in the threatened rainforests of Papua New Guinea (PNG), and mapping evidence of similar projects worldwide. Our approach is framed by Planetary Health, aiming to safeguard both human health and the natural systems that underpin it. Our rationale is demonstrated through a summary of health needs and forest conservation issues across PNG, and how these play out locally. We outline differing types of integrated conservation and health interventions worldwide, providing examples from Borneo, Uganda, India and elsewhere. We then describe what we are doing on-the-ground in PNG, which includes expansion of a rainforest conservation area alongside the establishment of a nurse-staffed aid post, and an educational intervention conceptually linking forest conservation and health. Importantly, we explore some ethical considerations on the conditionality of medical provision and identify key challenges to the successful implementation of such projects. The latter include: avoiding cross-sectoral blindness and achieving genuine interdisciplinary working; the weak evidence base justifying projects; and temporal-spatial issues. We conclude by suggesting how projects integrating actions on health and conservation SDGs can benefit from (and contribute to) the energy of the emerging Planetary Health movement.

Benefit Sharing Schema from the Forest: Identifying Potential Distributions to Customary Communities in Teluk Bintuni District, Indonesia

This study identifies the benefits that traditional communities receive from the tropical rain forest in New Guinea, Indonesia. In this study, various benefit sharing schema developed by forest concession holder are assessed to understand the precise outcome compared to traditional welfare solutions. It further aims to identify benefit sharing schemas applied by concession investors in the forest sector and assesses these schema based on equitable principles. A questionnaire and semi‑structured interviews were used to collect data from traditional communities, concession holders, and the government. Interviews and field observations were randomly conducted and then analyzed for both quantitative and qualitative descriptions. The results indicate that there were five benefits sharing schemas i.e., those based on financial schema, based on the market, based on infrastructure, based on social management, and based on the transfer of knowledge and technology. Overall, all the schemas that were developed did not fulfil the same criteria. However, there were only two schemas that were considered to be equal and efficient: the financial based‑schema and infrastructure based‑schema. This is indicated by the larger number of criteria and requirements that they fulfil. Yet, all the schemas still present various conflicts either between customary communities and the government or between the communities and investors.

Experiments with artificial nests provide evidence for ant community stratification and nest site limitation in a tropical forest

AbstractAnts are dominant in tropical forests and many species nest in hollow cavities. The manner in which species are vertically stratified in these complex habitats is not known, with lack of nest sites being proposed to limit ant populations. Here, we assess ant community stratification and nest site limitation in a lowland rainforest in New Guinea using experimental addition of artificial bamboo nests of two cavity sizes (small: ~12 mm large: ~32 mm diameter) placed at ground level, in the understorey, and in the canopy. We also conducted a pilot experiment to test the utility of nest translocation. Nests were checked for occupancy after 10 weeks and half of the occupied nests were then translocated between forest plots, while keeping same vertical position. Occupancy of small nests was much higher in the understorey and canopy than at ground level (~75% vs. ~25%). Translocation was successful, as a majority of nests was inhabited by the same species before and after translocation and there was no impact of translocation to a different plot compared to the control, except for a reduction in colony size at ground level. Our experiment demonstrates a vertical stratification in community composition of ants nesting in hollow dead cavities and shows that these ants are more nest site limited in the higher strata than at ground level. Use of small artificial cavities has great potential for future experimental studies, especially for those focused on arboreal ants, as occupancy is high and translocation does not negatively affect their colony size.Abstract in Tok Pisin is available with online material.

Determinants of Piper (Piperaceae) climber composition in a lowland tropical rainforest in New Guinea

Climbing plants form a substantial component of tropical forest diversity. Climbers are a diverse group comprising various ecological strategies dependent on tree support and are affected by biotic and abiotic forest conditions. In a lowland primary tropical rainforest in Papua New Guinea, we studied the distribution of root climbers from genus Piper in relation to topography (slope, convexity, altitude) and properties of vegetation and of individual host trees (basal area of trees, and host tree size, abundance and species identity). In total, 1,058 Piper climber individuals belonging to 8 species occupied 13.7% of tree trunks with a diameter at breast height (DBH) > 1 cm. All Piper species generally avoided similar habitat conditions – higher altitude, steeper slopes, more closed canopy layer and bigger total basal area of host vegetation. The preferences of Piper climbers for some tree species are primarily determined by properties of host trees, mainly their DBH. Therefore, the probability of Piper presence on a tree increased with individual host tree DBH. Piper species were more frequently found on rare than common tree species. However, this relationship might be also explained by their affinity for higher tree DBH. Our findings point to non-random association between climbers and their host trees, in a complicated interplay with local environmental conditions. These interactions have very probably consequences for forest vegetation dynamics and maintenance of diversity.

What was the vegetation in northwest Australia during the Paleogene, 66–23million years ago?

Fossil pollen and spores preserved in drillcore from both the upper South Alligator River (SARV) in the Kakadu National Park, Northern Territory and the North-West Shelf, Western Australia provide the first record of plants and plant communities occupying the coast and adjacent hinterland in north-west Australia during the Paleogene 66 to 23million years ago. The palynologically-dominant woody taxon is Casuarinaceae, a family now comprising four genera of evergreen scleromorphic shrubs and trees native to Australia, New Guinea, South-east Asia and Pacific Islands. Rare taxa include genera now mostly restricted to temperate rainforest in New Guinea, New Caledonia, New Zealand, South-East Asia and/or Tasmania, e.g. Dacrydium, Phyllocladus and the Nothofagus subgenera Brassospora and Fuscospora. These appear to have existed in moist gorges on the Arnhem Land Plateau, Kakadu National Park. No evidence for Laurasian rainforest elements was found. The few taxa that have modern tropical affinities occur in Eocene or older sediments in Australia, e.g. Lygodium, Anacolosa, Elaeagnus, Malpighiaceae and Strasburgeriaceae. We conclude the wind-pollinated Oligocene to possibly Early Miocene vegetation in the upper SARV was Casuarinaceae sclerophyll forest or woodland growing under seasonally dry conditions and related to modern Allocasuarina/Casuarina formations. There are, however, strong floristic links to coastal communities growing under warm to hot, and seasonally to uniformly wet climates in north-west Australia during the Paleocene-Eocene.

Variably hungry caterpillars: predictive models and foliar chemistry suggest how to eat a rainforest.

A long-term goal in evolutionary ecology is to explain the incredible diversity of insect herbivores and patterns of host plant use in speciose groups like tropical Lepidoptera. Here, we used standardized food-web data, multigene phylogenies of both trophic levels and plant chemistry data to model interactions between Lepidoptera larvae (caterpillars) from two lineages (Geometridae and Pyraloidea) and plants in a species-rich lowland rainforest in New Guinea. Model parameters were used to make and test blind predictions for two hectares of an exhaustively sampled forest. For pyraloids, we relied on phylogeny alone and predicted 54% of species-level interactions, translating to 79% of all trophic links for individual insects, by sampling insects from only 15% of local woody plant diversity. The phylogenetic distribution of host-plant associations in polyphagous geometrids was less conserved, reducing accuracy. In a truly quantitative food web, only 40% of pair-wise interactions were described correctly in geometrids. Polyphenol oxidative activity (but not protein precipitation capacity) was important for understanding the occurrence of geometrids (but not pyraloids) across their hosts. When both foliar chemistry and plant phylogeny were included, we predicted geometrid-plant occurrence with 89% concordance. Such models help to test macroevolutionary hypotheses at the community level.

Low host specificity and abundance of frugivorous lepidoptera in the lowland rain forests of Papua New Guinea.

We studied a community of frugivorous Lepidoptera in the lowland rainforest of Papua New Guinea. Rearing revealed 122 species represented by 1,720 individuals from 326 woody plant species. Only fruits from 52% (171) of the plant species sampled were attacked. On average, Lepidoptera were reared from 1 in 89 fruits and a kilogram of fruit was attacked by 1.01 individuals. Host specificity of Lepidoptera was notably low: 69% (33) of species attacked plants from >1 family, 8% (4) fed on single family, 6% (3) on single genus and 17% (8) were monophagous. The average kilogram of fruits was infested by 0.81 individual from generalist species (defined here as feeding on >1 plant genus) and 0.07 individual from specialist species (feeding on a single host or congeneric hosts). Lepidoptera preferred smaller fruits with both smaller mesocarp and seeds. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialist and generalist species. The very low incidence of seed damage suggests that pre-dispersal seed predation by Lepidoptera does not play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen-Connell hypothesis.

Human impacts on two endemic cassowary species in Indonesian New Guinea

AbstractCassowaries are important seed dispersers in tropical rainforests of New Guinea, but little is known about their population ecology or their responses to human disturbance. We used camera traps to measure the occurrence, local abundance, and activity patterns of northern cassowaries Casuarius unappendiculatus in lowland forests near Nimbokrang, Papua, and dwarf cassowaries Casuarius bennetti in the Arfak Mountains, West Papua. Our goals were to assess human impacts on cassowaries at multiple spatial scales and to measure their activity patterns over an elevational divide. At fine spatial scales local abundance of cassowaries was strongly reduced in areas frequented by humans. At larger spatial scales the distance to the nearest village or drivable road did not affect local abundance but altered the stage structure of the individuals detected, with a higher proportion of juveniles relative to adults. Local abundance of cassowaries was unrelated to site usage by introduced pigs. Both populations studied were strongly diurnal and their activity patterns were not significantly different. Efforts to control hunting remain critical to sustaining cassowaries and the seed dispersal services they provide.

Gall‐forming insects in a lowland tropical rainforest: low species diversity in an extremely specialised guild

1. Gall‐forming insects are a guild of endophages that exhibit a high level of fidelity to their host plants, however, their level of host specificity is seldom explicitly tested.2. Gall‐forming insect taxa from 32 species of woody tropical plants with resolved phylogenetic relationships were collected and reared, representing 15 families from all the major clades of angiosperms, at three lowland rainforest locations in Madang, Papua New Guinea (PNG).3. More than 8800 galled plant parts were collected from 78 gall morphospecies at an average of 2.4 per host plant. Total species richness at the sampling sites was estimated to be 83–89. All but one morphospecies were monophagous resulting in an effective specialisation of 0.98.4. Specific leaf weight, foliar nitrogen, the presence of latex, and the successional preference of plant species all gave a phylogenetic signal, but only plant successional preference influenced the species richness of galls on analysis of phylogenetically independent contrasts. Gall species were distributed randomly among host plant species and showed no preference for any particular plant lineage. Furthermore, most gall‐forming taxa were evenly dispersed across the host plant phylogeny.5. In the tropical rainforests of New Guinea, gall‐forming insects are ubiquitous but occur in species‐poor assemblages. Local species richness is closely tied to the diversity of angiosperms owing to very high host specificity.6. Finally, galler species richness data from the literature across habitats and latitudes were compared and suggest that tropical rainforests may be richer in galls than previously acknowledged.

Disentangling the diversity of arboreal ant communities in tropical forest trees.

Tropical canopies are known for their high abundance and diversity of ants. However, the factors which enable coexistence of so many species in trees, and in particular, the role of foragers in determining local diversity, are not well understood. We censused nesting and foraging arboreal ant communities in two 0.32 ha plots of primary and secondary lowland rainforest in New Guinea and explored their species diversity and composition. Null models were used to test if the records of species foraging (but not nesting) in a tree were dependent on the spatial distribution of nests in surrounding trees. In total, 102 ant species from 389 trees occurred in the primary plot compared with only 50 species from 295 trees in the secondary forest plot. However, there was only a small difference in mean ant richness per tree between primary and secondary forest (3.8 and 3.3 sp. respectively) and considerably lower richness per tree was found only when nests were considered (1.5 sp. in both forests). About half of foraging individuals collected in a tree belonged to species which were not nesting in that tree. Null models showed that the ants foraging but not nesting in a tree are more likely to nest in nearby trees than would be expected at random. The effects of both forest stage and tree size traits were similar regardless of whether only foragers, only nests, or both datasets combined were considered. However, relative abundance distributions of species differed between foraging and nesting communities. The primary forest plot was dominated by native ant species, whereas invasive species were common in secondary forest. This study demonstrates the high contribution of foragers to arboreal ant diversity, indicating an important role of connectivity between trees, and also highlights the importance of primary vegetation for the conservation of native ant communities.

Molecular phylogeny and biogeography of the spider ants, genus Leptomyrmex Mayr (Hymenoptera: Formicidae)

This study provides the first phylogenetic reconstruction of the ant genus Leptomyrmex Mayr, a prominent endemic component of rain forest and wet sclerophyll forest in Australia, New Guinea and New Caledonia. Five genes are used to reconstruct phylogeny and estimate of ages of diversification in order to test congruence of the history of nuclear and mitochondrial genes: three protein-coding nuclear genes: arginine kinase (argK, 897 bp), long wavelength rhodopsin (LW Rh, 546 bp) and wingless (Wg, 409 bp), as well as the large subunit ribosomal gene 28S (482 bp) and the mitochondrial gene cytochrome oxidase I (COI, 658 bp). Four different partitioning schemes were tested for optimal resolving power; results show that partitioning by gene, translational pattern and codon position were uniformly favoured over less complex partitions. Nuclear markers showed relatively minor sequence divergence and provided strongly supported topology; phylogeny based solely on mtDNA produced somewhat conflicting topology but offered little power to resolve species complexes. Monophyly of the genus Leptomyrmex was recovered, as was the sister-group relationship of ‘micro-’ and ‘macro-’ Leptomyrmex species. Divergence dating analyses estimate that Leptomyrmex arose in the Eocene (stem age ∼44 million years ago (ma)), and that the ‘macro-’ species diverged from the ‘micro-’ species in the early Oligocene (∼31 ma). Diversification of the crown group ‘macro-’ and ‘micro-’ Leptomyrmex occurred in the Miocene (∼15 ma and 7.9 ma, respectively). New Guinean and New Caledonian lineages appear to have diverged from Australian lineages only recently (∼4.7 ma and 10.3 ma, respectively), and the latter clade is inferred to have reached New Caledonia from Australia via long distance dispersal. These results challenge previous hypotheses of Leptomyrmex classification and assumptions about their historical dispersal, but are in agreement with the current knowledge of the geological history of Melanesia.