Impacts by feral goats on critically endangered Crepidiastrum grandicollum (Compositae) endemic to the Ogasawara Islands

Oceanic islands are biodiversity hotspots with highly endemic ecosystems that are vulnerable to invasive alien species. Understanding the status of endangered species and identifying threats have the highest priority for insular biodiversity conservation. The two remaining populations of endangered Crepidiastrum grandicollum on Chichi-jima Island were studied for 5 years to describe their status and evaluate the impacts of feral goats (Capra hircus). The main cause of population decline was browsing by goats. The populations protected by the exclosures were stable but declined after an exclosure was removed. Even in the protected population, regeneration was limited outside the exclosures and in 1 year of the survey, a high proportion of feeding damage by moth larvae was observed in one population. These facts indicate that exclosures are not a sufficient conservation measure, and eradication of goats and population restoration in novel habitats are necessary to reduce the extinction risk of C. grandicollum.     

Conservation genetics of an endangered rainforest tree (Fontainea oraria – Euphorbiaceae) and implications for closely related species

Four new eastern Australian Fontainea species have beenrecently described and all have a limited distribution. F.oraria is the rarest, being restricted to 10 adult individualswithin a single site in regrowth littoral rainforest. In order todevelop adequate management strategies, this study was aimed atsurveying the genetic variability remaining within the species by usingRAPD analysis. To assist with the correct interpretation of the results,a matching study was conducted on four populations of the closelyrelated F. australis. Similar amounts of within-populationgenetic diversity were recorded for both species. The RAPD-based studysuggested that adult plants are contributing unevenly to successivegenerations. RAPD analysis also recognised a close evolutionaryrelationship between F. oraria and F. australis.Sequencing of cpDNA (trnL-F) and nrDNA (ITS2) regions,confirmed recent divergence and possibly some historical reticulationbetween these two species and two other members of the genus. Ofparticular interest was the recognition that one of the F.australis populations (Limpinwood) represented a novel genotypiccombination in need of conservation attention. The implications of theRAPD and sequencing results are discussed in reference to theirinfluence upon the development of adequate conservation strategies forall important conservation units.     

Conservation genetics of two critically endangered island dwarf carnivores

Genetic diversity is crucial for conservation biology and for understanding evolutionary processes. Oceanic islands harbor a unique biota and high endemism, with populations frequently facing detrimental genetic processes (e.g. drift, bottlenecks). Human activities like habitat transformation further increase extinction risk of insular biota. Mammals comprise the most endangered group among insular fauna. Our aim was to evaluate the genetic and evolutionary patterns of two critically endangered dwarf carnivores from Cozumel Island, the pygmy raccoon (Procyon pygmaeus) and the dwarf coati (Nasua nelsoni), at both historical and contemporary evolutionary scales. We also reviewed their genetic relationships with their mainland counterparts (P. lotor, N. narica), not intended to describe their phylogeny but to ascertain their endemism. Our mitochondrial results support that both Cozumel carnivores are divergent from continental populations, strengthening their endemic status. Both species showed moderate levels of nuclear genetic diversity that were, as expected for island populations, lower in comparison with their mainland congeneric species; they also exhibited significantly low population sizes. We documented historical and contemporary bottleneck signals for P. pygmaeus, whereas N. nelsoni may be suffering the initial stages of a bottleneck not yet fully manifested. The pygmy raccoon is structured into two isolated genetic clusters likely due to interactions with humans on the north of the island, where most potential for disease transmission and health problems exist. We also add evidence about the introduction of the mainland species into the island, risking genetic introgression and hybridization. We discuss specific conservation measures that should include our genetic information, directed to the long-term viability of these endemic carnivores.

     

New species ofAcremonium, Cylindrocarpon andVerticillium from soil in the Bonin (Ogasawara) Islands, Japan

Three new soil fungi from the Bonin (Ogasawara) Islands, Japan are described:Acremonium macroclavatum, characterized by large clavate guttulate conidia;Cylindrocarpon boninense, characterized by 3–7-septate clavate macroconidia, terminal or intercalary chlamydospores, rarely produced unicellular clavate microconidia; andVerticillium hahajimaense, characterized by conidial heads bearing cylindrical conidia, and catenulate chlamydospores.     

Conservation genetics of a critically endangered limpet genus and rediscovery of an extinct species

Background

A third of all known freshwater mollusk extinctions worldwide have occurred within a single medium-sized American drainage. The Mobile River Basin (MRB) of Alabama, a global hotspot of temperate freshwater biodiversity, was intensively industrialized during the 20^th century, driving 47 of its 139 endemic mollusk species to extinction. These include the ancylinid limpet Rhodacmea filosa, currently classified as extinct (IUCN Red List), a member of a critically endangered southeastern North American genus reduced to a single known extant population (of R. elatior) in the MRB.

Methodology/Principal Findings

We document here the tripling of known extant populations of this North American limpet genus with the rediscovery of enduring Rhodacmea filosa in a MRB tributary and of R. elatior in its type locality: the Green River, Kentucky, an Ohio River Basin (ORB) tributary. Rhodacmea species are diagnosed using untested conchological traits and we reassessed their systematic and conservation status across both basins using morphometric and genetic characters. Our data corroborated the taxonomic validity of Rhodacmea filosa and we inferred a within-MRB cladogenic origin from a common ancestor bearing the R. elatior shell phenotype. The geographically-isolated MRB and ORB R. elatior populations formed a cryptic species complex: although overlapping morphometrically, they exhibited a pronounced phylogenetic disjunction that greatly exceeded that of within-MRB R. elatior and R. filosa sister species.

Conclusions/Significance

Rhodacmea filosa, the type species of the genus, is not extinct. It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity. All three surviving populations of the genus Rhodacmea merit specific status. They collectively contain all known survivors of a phylogenetically highly distinctive North American endemic genus and therefore represent a concentrated fraction of continental freshwater gastropod biodiversity. We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction.     

Pollination and reproduction of Psychotria homalosperma,an endangered distylous tree endemic to the oceanic Bonin (Ogasawara) Islands,Japan

Distyly is usually rare or not observed in species thriving on oceanic islands. The rarity of this breeding system is probably because of the difficulty of colonization for distylous plants and the paucity of pollinators on oceanic islands. However, the endemic and endangered tree Psychotria homalosperma has maintained its distylous nature in the oceanic Bonin Islands, Japan. To understand how the distylous breeding system of P. homalosperma has been maintained on these islands and to characterize the reproduction systems, we studied the pollination and reproductive biology of this species. Specifically, we observed current flower visitors and estimated their effects on plant reproduction. We also examined the floral traits and floral volatiles of P. homalosperma to infer its original pollinators, because plant–pollinator relationships in the Bonin Islands have recently been disrupted by anthropological activities. Finally, we examined the fruit set and pollen tube growth in the stigmas under hand and open pollination. Although original pollinators were presumed to be moths with long proboscises, the introduced honeybee, Apis mellifera, was the most common flower visitor. The honeybee carried pollen grains only unidirectionally, from the short‐ to long‐styled morphs, because it could not reach the hidden stigmas of the short‐styled flowers, and long‐styled flowers set fruits 1.7–38 times more than short‐styled ones. This case study indicates that the instability of pollinator fauna can cause distylous species to be rare on oceanic islands.     

Soil fungal floras in the Bonin (Ogasawara) Islands, Japan

Soil fungi in the Bonin (Ogasawara) Islands, Japan are surveyed, and among a total of 370 isolates studied, more than 81 fungus species belonging to 47 genea are identified. The significance of the flora is discussed.     

Melanoderma boninense,a new species of Melanoderma (Polyporales,Agaricomycota) from the Bonin Islands in Japan

Melanoderma boninense is described and illustrated as a new species from the Bonin Islands, Japan, on the basis of morphological and phylogenetic investigations. This species is characterized by sessile basidiocarps with an ungulate pileus, a black crust on the pileus surface, pores 4–6/mm, a dimitic hyphal system comprising clamped generative hyphae and cyanophilous skeletal binding hyphae with or without a dextrinoid reaction, cylindrical basidiospores measuring 5.5–7.5 × 2–3 μm, and cystidioles on the sides of tubes and near the pore surface. Morphological examination of authentic specimens of other Melanoderma species revealed that the genus is variable in terms of the shape and size of cystidioles. A black crust on the pileus surface composed of palisade and highly agglutinated hyphae is a distinctive diagnostic morphological feature of Melanoderma that differentiates it from allied genera. Melanoderma boninense, which is currently known from a restricted area of the Bonin Islands, is potentially threatened by environmental reduction of the type locality due to the invasive tree Bischofia javanica.     

Population genetics of the threatened tree daisy Olearia gardneri (Asteraceae), conservation of a critically endangered species

All known populations of the nationally critical tree daisy, Olearia gardneri, were studied using AFLP markers. With fewer than 160 individual plants, Olearia gardneri is the third-rarest tree in New Zealand and a good model with which to study evolutionary process in fragmented endangered plants. Genetic variation was at similar levels to other long-lived tree species in New Zealand and also as in other studies to date had poor correspondence between genetic and geographic distance. Genetic factors such as inbreeding depression and the loss of genetic diversity might lower fitness and have substantial consequences for evolution and survival of rare threatened plants. Due to the decline of this species in recent times it is imperative that conservation measures are undertaken, including revegetation. Despite considerable emphasis on “eco-sourcing” in plant recovery programmes there is strong evidence that this may not be the best strategy for O. gardneri due to breeding system and population size considerations.     

MtDNA diversity of the critically endangered Mekong giant catfish (Pangasianodon gigas Chevey, 1913) and closely related species: implications for conservation

Catfishes of the family Pangasiidae are an important group that contributes significantly to the fisheries of the Mekong River basin. In recent times the populations of several catfish species have declined, thought to be due to overfishing and habitat changes brought about by anthropogenic influences. The Mekong giant catfish Pangasianodon gigas Chevey, 1913 is listed as Critically Endangered on the IUCN Red List. In the present study, we assessed the level of genetic diversity of nine catfish species using sequences of the large subunit of mitochondrial DNA (16S rRNA). Approximately 570 base pairs (bp) were sequenced from 672 individuals of nine species. In all species studied, haplotype diversity and nucleotide diversity ranged from 0.118±0.101 to 0.667±0.141 and from 0.0002±0.0003 to 0.0016±0.0013, respectively. Four haplotypes were detected among 16 samples from natural populations of the critically endangered Mekong giant catfish. The results, in spite of the limited sample size for some species investigated, indicated that the level of genetic variation observed in wild populations of the Mekong giant catfish (haplotype diversity=0.350±0.148, nucleotide diversity=0.0009±0.0008) is commensurate with that of some other related species. This finding indicates that (1) wild populations of the Mekong giant catfish might be more robust than currently thought or (2) present wild populations of this species carry a genetic signature of the historically larger population(s). Findings from this study also have important implications for conservation of the Mekong giant catfish, especially in designing and implementing artificial breeding programme for restocking purposes.     

Development of microsatellite markers for Stachyurus macrocarpus and Stachyurus macrocarpus var. prunifolius (Stachyuraceae), critically endangered shrub species endemic to the Bonin Islands

Stachyurus macrocarpus and S. macrocarpus var. prunifolius are critically endangered shrub species in the Bonin (Ogasawara) Islands, Japan. These species are extremely rare, and the numbers of individuals in wild populations are 68 in S. macrocarpus and 13 in S. macrocarpus var. prunifolius. For the investigation of genetic diversity, genetic structure and relatedness among remnant individuals of these endangered species, we developed eight microsatellite markers from S. macrocarpus var. prunifolius and characterized these markers for S. macrocarpus var. prunifolius and S. macrocarpus using all naturally occurring individuals of these species. The expected heterozygosities of these markers ranged from 0.14 to 0.67 in S. macrocarpus var. prunifolius, and from 0.02 to 0.84 in S. macrocarpus. The markers described here will be useful for investigating the genetic diversity, genetic structure and relatedness among remnant individuals, and planning the restoration of these critically endangered species.     

Conservation genetics of the endangered endemic Sambucus palmensis Link (Sambucaceae) from the Canary Islands

Five polymorphic microsatellites (simple sequence repeat; SSR) markers were used to estimate the levels of genetic variation within and among natural populations from different islands of the endangered endemic from the Canary Islands Sambucus palmensis Link (Sambucaceae). Genetic data were used to infer potential evolutionary processes that could have led to present genetic differentiation among islands. The levels of genetic variability of S. palmensis were considerably high; proportion of polymorphic loci (P = 100%), mean number of alleles per locus (A = 6.8), average expected heterozygosity (He = 0.499). In spite of its small population size and endemic character, 58 different multilocus genotypes were detected within the 165 individuals analyzed. All samples located in different islands always presented different multilocus genotypes. Principal Coordinates Analysis, genetic differentiation analysis (F _ST and G _ST ′) and Bayesian Cluster Analysis revealed significant genetic differences among populations located in different islands. However, this genetic differentiation was not recorded among Tenerife and La Gomera populations, possibly revealing the uncontrolled transfer of material between both islands. AMOVA analysis attributed 77% of the variance to differences within populations, whereas 8% was distributed between islands. The levels of genetic differentiation observed among populations, and the genetic diversity distribution within populations in S. palmensis, indicate that management should aim to conserve as many of the small populations as possible. Concentrating conservation efforts only on the few large populations would result in the likelihood of loss of genetic variability for the species.     

<Emphasis Type="Italic">Cylindrocladium</Emphasis> species and the related fungi isolated in the Ogasawara (Bonin) Islands and the Ryukyu Islands,Japan

A total of 28 deuteromycetous isolates obtained from forest environments in the Ogasawara (Bonin) Islands and the Ryukyu Islands, Japan, were identified to five Cylindrocladium and related fungal species (Calonectria kyotoensis (anamorph: Cylindrocladium floridanum), Cylindrocladiella lageniformis, Cylindrocladium camelliae, Cylindrocladium citri, and Cylindrocladium tenue), excluding two unknowns. Cylindrocladiella lageniformis is a new record, and the others are rarely reported in Japan.     

Genetic analysis and conservation of the endangered Canary Island woody sow-thistle, Sonchus gandogeri (Asteraceae)

Sonchus gandogeri, a woody sow-thistle, is an endangered Canary Island endemic with only two known populations, one in the El Golfo and another in the Las Esperillas of El Hierro. Amplified fragment length polymorphism (AFLP) markers were used to assess the genetic variation within and among populations. The mean genetic diversity of two populations was estimated to be 0.380, and the El Golfo population (0.380) had higher genetic diversity than the southeastern one (0.268). The unbiased Neis genetic identity between the two populations was 0.846. The mean genetic diversity of S. gandogeri was much higher than that of the other endangered plant species. This is perhaps due to breeding system, life form, extinction, and/or introgressive hybridization and hybrid origin of the taxon. This study also indicates that the two populations are not strongly differentiated (G_ST=0.149). This study suggests that S. gandogeri is more likely to become extinct due to environmental or demographic forces than genetic factors, such as inbreeding depression. More strict control of introduced herbivores is necessary to protect these populations, and germplasm collection for ex situ conservation is needed.     

The recent history and population structure of five Mandarina snail species from subtropical Ogasawara (Bonin Islands, Japan)

The effect of Pleistocene climate change on the organisms of tropical and subtropical regions is rather poorly understood. We therefore studied the land snail genus Mandarina (Bradybaenidae) of oceanic Ogasawara (Bonin Islands, Japan), with the aim of using population genetic data to understand their recent history. Our analysis of a mitochondrial 16S ribosomal RNA region from more than 600 snails in five ground-living species suggests that populations on the small islands of Mukoujima, Anejima, Imotojima and Meijima, as well as on the low-lying southern and central parts of Hahajima, have probably undergone recent bottlenecks followed by subsequent expansions. Except between the main island of Hahajima and Mukouijima, there is almost no evidence for gene flow among islands even though the islands were connected repeatedly by land bridges through the Pleistocene. Within islands the population structure is severe, suggestive of a long-term, low level of gene flow (F(ST) is frequently greater than 0.5 among geographically close populations). Finally, there is a marked genetic patchiness, meaning that genetically close populations are sometimes separated by genetically distant populations. These patterns could be a consequence of expansion from bottlenecks, low active dispersal and founder effects caused by rare long-distance migrants. Unfortunately, the exact nature of the refugia and bottlenecks remains unknown because the palaeoclimate of this region is poorly understood. Dating the population size changes is also challenging because the molecular clock is uncertain. We suggest, however, that arid conditions or deforestation induced by decreased atmospheric CO(2) may have been the main factor in determining population size.     

Complete genotyping in conservation genetics, a case study of a critically endangered shrub, Stachyurus macrocarpus var. prunifolius (Stachyuraceae) in the Ogasawara Islands, Japan

More than 3,000 species are listed as critically endangered worldwide, and various conservation measures such as habitat restoration, assisted reproduction and establishment of ex situ populations would be required to prevent their extinction. We determined the genotype of all 15 known wild clumps using nuclear microsatellite markers for Stachyurus macrocarpus var. prunifolius, a critically endangered shrub endemic to the Ogasawara (Bonin) Islands of Japan. In addition, the seedlings propagated from seeds taken from one wild clumps were genotyped. The results of complete genotyping showed that both wild and nursery populations had population-specific alleles. Two alleles were detected only in the nursery population, indicating the existence of undiscovered mature individuals in the wild. Four alleles were found only in the wild and were detected in two geographically isolated clumps, and this finding may propose that re-introduction and transplantation between different sites requires sensitive handling in terms of the conservation of evolutionary significant units. These results show that complete genotyping can provide essential genetic and ecological information for effective management of endangered species.     

Dactylella chichisimensis, sp. nov. in the Bonin (Ogasawara) Islands, Japan

ADactylella isolate obtained from soil in the Bonin (Ogasawara) Islands, Japan is described and illustrated as a new species,D. chichisimensis. The fungus is characterized by single terminal multiseptate clavate or ellipsoidal conidia at the apex of simple conidiophores and mycelium that forms chlamydospores and sclerotia. A key is provided for sixDactylella species that produce primary clavate or ellipsoidal conidia at the apex of simple conidiophores.