Isolation of polymorphic microsatellite loci in Livistona chinensis (Jacq.) R.Br. ex Mart. var. boninensis Becc., an endemic palm species of the oceanic Bonin Islands, Japan

A set of microsatellites markers were developed for Livistona chinensis var. boninensis, an endemic palm tree of the Bonin Islands. We obtained 123 sequences containing unique microsatellites from an enriched library. Twelve loci were screened for their feasibility using 32 trees. They showed polymorphisms with two to nine alleles per locus. No significant deviation from Hardy–Weinberg equilibrium was observed for 11 loci. No genotypic disequilibrium was detected between any two of the loci. Total exclusionary powers for the first and the second parents were 0.978774 and 0.998987, respectively. These markers will allow us to investigate the gene flow within/among populations of the species.     

Genetic differentiation among populations of an oceanic island: The case of Metrosideros boninensis, an endangered endemic tree species in the Bonin Islands

Conservation of endemic species on oceanic islands is an essential issue for biodiversity conservation. Metrosideros boninensis (Myrtaceae) is an endangered tree species endemic to the Bonin Islands of the western North Pacific Ocean. This species is considered to be extremely rare with less than 400 adult individuals, a number that has fluctuated between the 1880s and 1980s through human influence. We analyzed the genetic diversity and genetic structure of this species using amplified fragment length polymorphism markers and microsatellite markers. Genetic diversity of M. boninensis was extremely low compared to related taxa and similar endemic species from small islands. This low genetic diversity might be attributed to a stepwise colonization process with repeated founder bottlenecks in the dispersal pathway to the Bonin Islands. Populations of M. boninensis showed significant genetic differentiation and isolation by distance over a small geographical scale, despite the fact that this species should have extensive gene dispersal ability. This genetic differentiation might be caused by limited gene flow via pollen and seed among populations and genetic drift amid a small number of remnant individuals. Taken together, these findings suggest that the genetic diversity and connectivity of tree populations on islands are more vulnerable to habitat fragmentation than previously thought. We offer some recommendations for management to ameliorate habitat fragmentation and biological invasion.     

Development and characterization of microsatellite markers for Hibiscus glaber Matsum. ex Nakai, an endemic tree species of the oceanic Bonin Islands, Japan

Polymorphic microsatellite markers were developed for Hibiscus glaber, an endemic tree of the Bonin Islands. Eighty-seven of the 208 sequences from an enriched library were unique and containing microsatellites. Ten loci were proved to be highly polymorphic among 78 individuals from the Nishi-jima Island. Total exclusionary powers for the first and the second parents were 99.989% and 99.999%, respectively. Nine loci also amplified single fragment from genomic DNA of H. tiliaceus, a related and widespread congener. Our markers can be reliably used for the estimation of current gene flow within/among populations of the two woody Hibiscus species.     

Phylogenetic analyses suggest a hybrid origin of the figs (Moraceae: Ficus) that are endemic to the Ogasawara (Bonin) Islands, Japan

The Ogasawara Islands are oceanic islands and harbor a unique endemic flora. There are three fig species (Ficus boninsimae, F. nishimurae and F. iidaiana) endemic to the Ogasawara Islands, and these species have been considered to be closely related to Ficus erecta, and to have diverged within the islands. However, this hypothesis remains uncertain. To investigate this issue, we assessed the phylogenetic relationships of the Ogasawara figs and their close relatives occurring in Japan, Taiwan and South China based on six plastid genome regions, nuclear ITS region and two nuclear genes. The plastid genome-based tree indicated a close relationship between the Ogasawara figs and F. erecta, whereas some of the nuclear gene-based trees suggested this relationship was not so close. In addition, the phylogenetic analyses of the pollinating wasps associated with these fig species based on the nuclear 28S rRNA and mitochondrial cytB genes suggested that the fig-pollinating wasps of F. erecta are not sister to those of the Ogasawara figs These results suggest the occurrence of an early hybridization event(s) in the lineage leading to the Ogasawara figs.     

Reed community restoration projects with citizen participation: an example of the practical use of Satoyama landscape resources in Shiga Prefecture, Japan

Today, Japan strives to preserve some of its rural Satoyama landscapes in a sustainable way in order to ensure the survival of some well-functioning rural ecosystems in the face of continuing urbanization on the one hand and the neglect of such landscapes on the other. In the Lake Biwa watershed area in Shiga Prefecture, Satoyama landscapes comprise woodlands, grasslands, dry and wet fields, residential areas, and the lakeshore. The area today faces two major challenges: first, how to use local natural resources in a sustainable way to avoid further neglect or destruction of Satoyama landscapes; and second, how to reorganize the management of Satoyama forest and lakeshore resources. The results of our investigation showed how solutions to the above issues were found in the context of lakeshore projects aimed at restoring reed (Phragmites communis) communities, which are important component of the Lake Biwa Satoyama landscape. Since 2002, four such projects have been successfully undertaken through the efficient use of local forest resources, mainly wood and bamboo, in wave dissipation structures and jetties which facilitate the expansion of reed communities. Management was reorganized and now consists of stakeholders which include the original Satoyama management communities, governmental bodies, resident and nonresident citizens, and nongovernmental and nonprofit organizations. The projects are a unique attempt to revive Satoyama watershed landscapes, and may serve as models in other watershed areas.     

Natural infections of Clinostomum complanatum (Trematoda: Clinostomatidae) in wild herons and egrets, Tottori Prefecture, Japan.

Nycticorax nycticorax, Ardea cinerea, Egretta garzetta, and Egretta intermedia were naturally infected with Clinostomum complanatum (Trematoda: Clinostomatidae) among fourteen wild herons, seven wild egrets and one wild bittern evaluated at the Veterinary Hospital of Tottori University, Tottori, Japan. The latter three species of heron and egrets are reported for the first time as definitive hosts of this parasite in Japan.     

Epidemiological characteristics of tsutsugamushi disease in Oita Prefecture, Japan: yearly and monthly occurrences of its infections and serotypes of its causative agent, Orientia tsutsugamushi, during 1984--2005.

Using indirect immunofluorescence assay, we examined the sera of 561 patients from November 1984 to February 2005 to determine the incidence of tsutsugamushi disease (scrub typhus) in Oita Prefecture, Japan. The results obtained were positive in 384 individuals (68.4%). Municipalities where patients were presumed to have been infected with Orientia tsutsugamushi were Taketa City (41.7%), Oyama Town (13.5%), and Ogi Town (8.3%). Infections occurred most often in October, November, and December. A small number of cases occurred from January to May. The serotypes Kuroki (47.5%), Kawasaki (42.5%), and Karp (10.0%) were detected by genetic analysis of O. tsutsugamushi DNA extracted from the blood of 120 patients. The gene sequences of the Kuroki type were highly homologous to that of the Nishino strain. The gene sequences of the Kawasaki type were identical to that of the Kawasaki strain. The gene sequence of the Karp type was highly homologous to that of the JP-2 type. To determine the distribution of vector mites, 558 wild rodents were captured and 72010 mites attached to these rodents were collected from 1982 to 1998. Six genera and 16 species of trombiculid mites were collected. Leptotrombidium pallidum and L. scutellare, which are known to be mite vectors for tsutsugamushi disease, accounted for 20.5% and 5.9%, respectively, of all trombiculid mites collected. The geographical distribution of cases roughly coincided with the distribution of L. scutellare. In Oita Prefecture, L. scutellare is presumed to primarily transmit tsutsugamushi disease. In addition, our results also suggest that L. pallidum transmits the Karp type of the causative rickettsia in some municipalities.