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Oceanic islands are simplified ecosystems, which are very useful for understanding the processes related to the structuring of natural communities and for assessing cascade effects after perturbations. Socorro Island in the Pacific Ocean reaches up to 1040 m in elevation, and the northeastern side that faces trade winds is more humid than the leeward southwestern side. Apparently, the lack of freshwater throughout most of the island has prevented the spread of invasive cats and sheep to the north, but these species have severely impacted land bird communities on the southern side, where they have potentially disrupted functions such as the top-down control of herbivory. We tested the relative importance of bottom-up (soil and foliage nutrient availability) and top-down (predation of insect herbivores) drivers of herbivory in three endemic tree species. By experimentally excluding birds, we assessed changes in herbivory when top-down control was disrupted, and we also evaluated herbivore predation rates using artificial caterpillars. Our findings suggest that the herbivory patterns on Socorro Island are driven by the top-down control of herbivores by land birds, because their exclusion resulted in higher herbivory (12%) despite low nitrogen content (bottom-up control) of leaves on the north side, whereas the leaves were richer in nitrogen on the south side but no change in herbivory was observed when birds were excluded, and overall, herbivory was 30% higher than in the north, suggesting release of herbivores from top down control on the south side, probably due to effects of invasive predators (cats) or sheep, which may have reduced suitable bird habitats. A better understanding of how drivers of ecological interactions operate on Socorro Island may increase the likelihood of success of future restoration programs.
Predicting the distribution of alien species in areas not yet reached or where the species are still found in low abundance is crucial for implementing timely management strategies. Miconia calvescens has become one of the worst plant invaders in the Pacific including in the Society Islands (French Polynesia), the Hawaiian Islands, and tropical Australia. The species has been recently introduced to the Marquesas Islands (French Polynesia) where it started to spread. In this study, we aimed at predicting the potential distribution of Miconia across this archipelago. MAXENT modelling based on ∼3,000 occurrence records from the native and introduced ranges of the species was used to predict its equilibrium distribution. Two types of environmental variables acting at different scales were considered: (1) climate variables at a 1km scale for predicting the invasion risk over still Miconia-free Marquesan islands; and (2) topographic variables at a 10 m scale for refining prospections and guiding management strategies on the islands of Nuku Hiva and Fatu Hiva where Miconia currently occupies ∼0.01% of the surface. Results differed substantially according to the origin of inputted occurrence records but models generally indicated that Miconia has the potential to spread over all inhabited Marquesan islands and over half of Nuku Hiva and a third of Fatu Hiva. Our approach provides valuable information for stakeholders to prevent future outbreaks. Without strong biosecurity measures, an early warning system, and appropriate control strategies in areas where it is already naturalized, Miconia could become a great threat to the outstanding biodiversity of the Marquesas Islands.
Taiwan is at the northeastern limits of the Asian center of diversity for fruit flies in the tribe Dacini, and the country has several endemic species. Between 2013 and 2015, we surveyed the diversity of dacine fruit flies in Taiwan using kairomone baited traps and found 15 species. We report four species for the first time in Taiwan and figure them: Bactrocera nigrifacia (Zhang, Ji, & Chen 2011), B.rubigina (Wang & Zhao 1989), B. dorsaloides (Hardy & Adachi 1954) and B. bhutaniae (Drew & Romig 2013). For the species that are classified as pests, we explored how their spatial distribution correlates with elevation. The oriental fruit fly, Bactrocera dorsalis (Hendel 1912), is the most abundant pest on the island, but decreases sharply in abundance at higher elevations. Other pest species occur in much smaller numbers and respond differently to elevation and latitude. We also re-evaluated all records of previously recorded species and add our records to provide a checklist with 30 species of Dacini that occur in Taiwan. All species are regarded as native, six are endemic, and seven are agricultural pests. Historical records were georeferenced and plotted on maps along with records from the 2013–2015 survey to collate all known distribution data. We briefly discuss the state of knowledge of the fruit flies in Taiwan and how the distribution and host usage of Dacini may change in the future. Finally, considering the economic importance of the group, our understanding of their diversity and distributions is surprisingly poor.
Talāsiga is a term frequently used in the literature to describe Fijian landscapes with a distinct pattern of plants and soils. The specific meaning in Fijian is unclear and there are varying interpretations of the term in the literature, although authors agree that such areas are indicative of low soil fertility. This paper examines the early literature on talāsiga, and attempts to reconcile the differences in use. The possible processes of development of such conditions from forest are discussed and data are presented from recent field studies on the progress from forest to grassland evolution in a 30-year time frame at Seaqaqa, Vanua Levu. The evidence points to the likely change over substantial areas from forest to highly degraded soils and associated grass/fern/shrub vegetation within a very short (<50 years) time frame. Such changes will have dramatic impacts on farmers using such lands.
The taxonomy of Hibiscus species in section Lilibiscus in Fiji is reappraised in the light of recent field and morphological studies. Six pre-European contact species are recognized. These comprise four Fiji endemic species, three of which are new and described: H. bennettii L.Thoms. and Braglia from Mt. Delaikoro, Vanua Levu; H. bragliae L.Thoms. from Ovalau; and H.macverryi L.Thoms. and Braglia from Macuata Province, Vanua Levu and Taveuni. The fourth Fiji endemic, Hibiscus storckii Seem., was first collected on Taveuni in 1860 and is here reinstated. Hibiscus cooperi Hort. Ex Lemaire, a species generally associated with the South Pacific region, has been confused in recent times with H. storckii. Hibiscus cooperi is lectotypified and reinstated. Hibiscus cooperi and H. rosa-sinensis L. are both considered ancient, pre-European introductions into the Pacific Islands. The Fiji archipelago is recognized as a secondary center of diversity and speciation in sect. Lilibiscus in the South Pacific. A botanical key is provided for the six Lilibiscus species that were present in the South Pacific Islands prior to European contact. All four Fiji endemic Lilibiscus species fall into the IUCN Critically Endangered (CR) Red List category and are highly threatened in the wild from climate change and associated extreme events including tropical cyclones, flooding, and landslides, as well as displacement by environmentally invasive species and through hybridization with introduced Hibiscus species. They are in urgent need of more intensive field survey followed by complementary in situ and ex situ conservation actions.
A new genus and species of skink, Kuniesaurus albiauris, is here described from the Île des Pins off southern New Caledonia. This new taxon possesses a unique suite of morphological apomorphies (scalation) that does not allow it to be placed in any existing Australasian eugongylid genus. It is known only from a single area in dense coastal forest on limestone, on the main island of the Île des Pins. The species area of occupancy is restricted, and the habitat occupied under threat from the spread of the highly invasive Little Red Fire Ant Wasmannia auropunctata. These factors place this new skink at a level of risk sufficient for it to be listed as Critically Endangered under IUCN Red List criteria. The affinities of the lizard fauna of the Île des Pins with respect to that present on southern New Caledonia are also discussed, most notably the absence from the Ile des Pins of taxa typically restricted to ultramafic surfaces.
A new species of skink in the genus Epibator is described from Île Walpole, a small, isolated, raised vegetated limestone platform, ∼200km ESE of southern New Caledonia. The new species is distinguished from its congeners Epibator nigrofasciolatus and E. greeri primarily by its coloration and pattern (both species), differences in scalation (greeri), and substantial genetic differentiation (nigrofasciolatus). The new species is the only extant endemic terrestrial vertebrate onWalpole. The island is small (<1.7km2), and has a long history of past human occupation (over the last 2,500 years, including European-era exploitation for guano), resulting in degradation of the vegetation cover and introduction of invasive animal species, most significantly ants (Little Fire Ant, Yellow Crazy Ant) and rats (Pacific Rat). The species' very limited distribution in combination with the threats posed by invasive species place it at a level of risk sufficient to be considered as Critically Endangered under IUCN Red List criteria.
New records of early life stages of cephalopods are presented based on planktonic collections carried out around Easter Island (Rapa Nui; 27°7′S, 109°21′W) and at the nearby Apolo Seamount (located at ∼7 nautical miles southwest from Easter Island) during March and September 2015 and March 2016. A total of 13 individuals were collected, comprising four families (Octopodidae, Ommastrephidae, Chtenopterygidae, and Enoploteuthidae) and five potential genera/types (Octopus sp., Chtenopteryx sp., rhynchoteuthion paralarvae, and two undetermined Enoploteuthid paralarvae). Cephalopod mantle lengths (ML) ranged from 0.8 to 4.5mm, with 65% of them (mainly Octopodidae) corresponding to newly hatched paralarvae of ∼1mm ML, and 35% to rhynchoteuthion and early stages of oceanic squids of around 1.5–4.5mm ML. These results provide the first records on composition and presence of early stages of cephalopods around a remote Chilean Pacific Island, while also providing a morphological and molecular basis to validate the identity of Octopus rapanui (but not Callistoctopus, as currently recorded), Ommastrephes bartramii and Chtenopteryx sp. around Rapa Nui waters. Despite adult Octopodidae and Ommastrephidae having been previously recorded at these latitudes, the current findings provide evidence to suggest that the northwest side of Easter Island, and one of the nearby seamounts, may provide a suitable spawning ground for benthic and pelagic species of cephalopods inhabiting these areas. For Chtenopterygidae and Enoploteuthidae, this is the first record for the Rapa Nui ecoregion.
In an attempt to add to our knowledge of the biodiversity of helminths infecting Philippine amphibians, three species of dicroglossid frogs (Dicroglossidae) were examined for helminths: Limnonectes macrocephalus (n = 5), L. visayanus (n=5), and L. woodworthi (n=5). Wefound four species of Nematoda (Abbreviata bufonis, Aplectana samarensis, Falcaustra dubia, and Seuratascaris numidica) and one species of Acanthocephala, Peudoacanthocephalus bufonis. Falcaustria dubia in L. macrocephalus had the greatest mean intensity of infection (15.5±2.1 SD). Rather than possessing a unique helminth fauna, dicroglossid frogs from the Philippines are infected by generalist helminths that also infect other species of frogs. Twelve new host records are reported.
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