The influence of non-native species on native ecosystems is not predicted easily when interspecific interactions are complex. Species removal can result in unexpected and undesired changes to other ...ecosystem components. I examined whether invasive non-native species may both harm and provide refugia for endangered native species. The invasive non-native plant Casuarina stricta has damaged the native flora and caused decline of the snail fauna on the Ogasawara Islands, Japan. On Anijima in 2006 and 2009, I examined endemic land snails in the genus Ogasawarana. I compared the density of live specimens and frequency of prédation scars (from black rats Rattus rattus) on empty shells in native vegetation and Casuarina forests. The density of land snails was greater in native vegetation than in Casuarina forests in 2006. Nevertheless, radical declines in the density of land snails occurred in native vegetation since 2006 in association with increasing prédation by black rats. In contrast, abundance of Ogasawarana did not decline in the Casuarina forest, where shells with prédation scars from rats were rare. As a result, the density of snails was greater in the Casuarina forest than in native vegetation. Removal of Casuarina was associated with an increased proportion of shells with prédation scars from rats and a decrease in the density of Ogasawarana. The thick and dense litter of Casuarina appears to provide refugia for native land snails by protecting them from prédation by rats; thus, eradication of rats should precede eradication of Casuarina. Adaptive strategies, particularly those that consider the removal order of non-native species, are crucial to minimizing the unintended effects of eradication on native species. In addition, my results suggested that in some cases a given non-native species can be used to mitigate the impacts of other non-native species on native species. La influencia de especies introducidas sobre los ecosistemas nativos no es pronosticada fácilmente cuando las interacciones interespecíficas son complejas. La remoción de especies puede resultar en cambios inesperados e indeseables en otros componentes del ecosistema. Examiné sí las especies introducidas invasoras pueden dañar y proporcionar refugios para especies nativas en peligro. La planta introducida invasora Casuarina stricta ha dañado la flora nativa y causado la declinación de la fauna de caracoles en las Islas Ogasawara, Japón. En Anijima, entre 2006 y 2009, examiné los caracoles terrestres endémicos del género Ogasawarana. Comparé la densidad de especímenes vivos y la frecuencia de cicatrices de depredación (por ratas negras Rattus rattus) en conchas vacías en la vegetación nativa y en bosques de Casuarina. La densidad de caracoles terrestres fue mayor en la vegetación nativa que en los bosques de Casuarina en 2006. Sin embargo, a partir de 2006 ocurrieron declinaciones radicales en la densidad de caracoles terrestres en la vegetación nativa asociadas con la depredación por ratas. En contraste, la abundancia de Ogasawarana no declinó en el bosque de Casuarina, donde las conchas con cicatrices de depredación por ratas fueron raras. Como un resultado, la densidad de caracoles fue mayor en el bosque de Casuarina que en la vegetación nativa. La remoción de Casuarina estuvo asociada con un incremento en la proporción de caracoles con cicatrices de depredación por ratas y un decremento en la densidad de Ogasawarana. La hojarasca gruesa y densa de Casuarina parece proporcionar refugio a los caracoles terrestres protegiéndolos de la depredación por ratas; por lo tanto, la erradicación de ratas debe preceder la erradicación de Casuarina. Estrategias adaptativas, particularmente las que consideran la remoción de especies introducidas, son cruciales para minimizar los efectos inesperados de la erradicación sobre las especies nativas. Adicionalmente, mis resultados sugieren que, en algunos casos, una especie introducida puede ser utilizada para mitigar los impactos de otras especies introducidas sobre las especies nativas.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
We have decomposed to symmetric and asymmetric modes the mass-TKE fission fragment distributions calculated by 4-dimensional Langevin approach and observed how the dominant fission mode and symmetric ...mode change as functions of Formula: see text of the fissioning system in the actinides and trans-actinide region. As a result, we found that the symmetric mode makes a sudden transition from super-long to super short fission mode around
Es. The dominant fission modes on the other hand, are persistently asymmetric except for
Fm,
Fm and
Md when the dominant fission mode suddenly becomes symmetric although it returns to the asymmetric mode around
No. These correlated "twin transitions" have been known empirically by Darleane Hoffman and her group back in 1989, but for the first time we have given a clear explanation in terms of a dynamical model of nuclear fission. More specifically, since we kept the shape model parameters unchanged over the entire mass region, we conclude that the correlated twin transition emerge naturally from the dynamics in 4-D potential energy surface.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Nonmarine molluscs are the major animal group with the greatest number of recorded extinctions due to anthropogenic impacts, and that number is certainly a serious underestimate. Land snails, ...particularly endemic land snails of oceanic islands, are the group of molluscs that have sustained the most extinctions. Understanding their ecology and the evolutionary processes that have led to their extreme vulnerability is crucial if we are to be able to conserve these diverse and important species. Oceanic island snails tend to have low α-diversity and high β-diversity, and divergence of habitat use among related species is known to occur in some radiations of land snails on oceanic islands. Processes of speciation and ecological interaction are possible major drivers of these patterns. The ecological opportunities available at the initial stage of insular evolution and the scarcity of effective predators may have led to divergence of habitat use and high β-diversity in oceanic island snails. Fewer and less diverse predators on oceanic islands lead to the evolution of fewer and less diverse defense traits in oceanic island snails, which results in their high vulnerability to non-native predators. High β-diversity of oceanic island snails also results in great vulnerability to habitat loss. Accordingly, the high susceptibility of oceanic island snails to extinction reflects their evolutionary history.
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Long‐distance dispersal (LDD) is a critical process in the distribution of less‐migratory organisms. Migratory birds are considered the principal vector of LDD, especially over extremely long ...distances such as between continents. However, there has been no evidence of LDD spanning thousands of kilometers, even via birds. In this study, we collected a freshwater snail attached to a Latham's snipe. This snail was identified as the genus
Glyptophysa
through morphological and molecular identification based on four genetic regions. Considering the migration route of the bird and the distribution of the molluscan genus, we conclude that the snail was attached to a bird which migrated over 4000 km across the ocean. This finding demonstrates the LDD on an intercontinental scale of an organism via a migratory bird, which many biologists have long presumed to occur.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background
To grasp the processes of spatial genetic structuring in open and connectable marine environments is the principal study goal in molecular biological studies. Comparative seascape genetics ...using multiple species are a powerful approach to understand the physical geographic and oceanographic effects on genetic variation. Besides, species-specific ecological traits such as dispersal abilities and habitat specificity are important factors for spatial genetic structuring.
Methods and Results
We focused on the sister marine snail species
Tegula kusairo
and
T. xanthostigma
around the Japanese mainland, which have contrasting habitat specificities for wave strength.
Tegula kusairo
only inhabits sheltered coastal environments, while
T. xanthostigma
is found mainly on wave-exposed rocky shores facing the open sea. We estimated their genetic diversity indices and levels of population differentiation based on mtDNA. We found that the genetic diversity of
T. kusairo
was lower than that of
T. xanthostigma
, while their level of population genetic differentiation was higher than that of
T. xanthostigma
. Namely, the species specific to weak wave environments had a higher level of population genetic differentiation than the species specific to strong wave action.
Conclusion
Ecological traits linked not only to dispersal abilities but also to habitat specificity can influence genetic variation in a pair of closely related sister species distributed in the same seascape.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Direct growth of anticorrosive magnesium hydroxide films containing Mg-Al layered double hydroxide with anion-exchangeability on magnesium alloy were successfully realized by a simple, easy, ...environmentally friendly, and chemical-free steam coating method. The crystal structures, chemical composition, surface morphologies, and chemical bonding states of the film were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM) measurements. All the films had thicknesses ranging from 2 to 68 mu m depending on the preparation conditions. The films had two crystal structures that were composed of crystalline Mg(OH) sub(2) and carbonate Mg-Al layered double hydroxide (LDH). The corrosion resistant performances of the films in 5 wt% NaCl aqueous solution were investigated by electrochemical measurements. The potentiodynamic polarization curves revealed that the corrosion current density (j sub(corr)) of a sample treated at 433 K for 6 h decreased by more than six orders of magnitude as compared to that of the bare magnesium alloy, indicating that the film had an inhibiting effect on the corrosion reaction. The formation mechanism of the film was also discussed.
Whether evolutionary history is mostly contingent or deterministic has been given much focus in the field of evolutionary biology. Studies addressing this issue have been conducted theoretically, ...based on models, and experimentally, based on microcosms. It has been argued that the shape of the adaptive landscape and mutation rate are major determinants of replicated phenotypic evolution. In the present study, to incorporate the effects of phenotypic plasticity, we constructed a model using tree-like organisms. In this model, the basic rules used to develop trees are genetically determined, but tree shape (described by the number and aspect ratio of the branches) is determined by both genetic components and plasticity. The results of the simulation show that the tree shapes become more deterministic under higher mutation rates. However, the tree shape became most contingent and diverse at the lower mutation rate. In this situation, the variances of the genetically determinant characters were low, but the variance of the tree shape is rather high, suggesting that phenotypic plasticity results in this contingency and diversity of tree shape. The present findings suggest that plasticity cannot be ignored as a factor that increases contingency and diversity of evolutionary outcomes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Aim
Vicariance events have been proposed as a major source of lineage divergence on continental islands, whereas dispersal events followed by isolation have been proposed as the major cause on ...oceanic islands. However, organisms on continental islands may include taxa with characteristics similar to those on oceanic islands. Lineage divergence unassociated with the geological events that separated islands may also have occurred. This study addresses these possibilities through morphological and molecular phylogeographic analyses of land snails (Bradybaena) on continental islands.
Location
Samples were mainly collected on the Ryukyu and Izu Islands in Japan.
Methods
Molecular phylogenetic analyses using mtDNA (16S rRNA+COI) and nDNA (18S rRNA+ITS1+5.8S rRNA+ITS2+28S rRNA) were conducted for 225 individuals comprising B. circulus, B. phaeogramma and four of its subspecies endemic to the Ryukyu Islands. Shell and genital morphologies were also examined using qualitative and statistical methods.
Results
The Bradybaena populations examined were phylogenetically classified into six major clades whose divergence occurred during either Miocene‐Pliocene or Pliocene‐Pleistocene. Although phylogeographic patterns estimated on the basis of the 16S rRNA gene support the vicariance hypothesis for the origin of the major clades of Bradybaena, the phylogeographic patterns estimated by COI showed that these major clades resulted from diversification before the archipelagos separated from the continent. Both of these phylogeographic patterns suggest that genetic divergence occurred by dispersal from the southern to northern islands after divergence of major clades. The inferred phylogenies document parallel morphological evolution, yielding phylogenetic, morphological and taxonomic incongruences that created mosaic geographical patterns in the distribution of nominal taxa.
Main conclusions
Lineage diversification in endemic species on continental islands can occur before archipelago separation or subsequently via dispersal, as is seen in species on oceanic islands. Mechanisms other than vicariance should also be considered when estimating processes that created geographical patterns of genetic variations on continental islands.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The fourth version of the Japanese Evaluated Nuclear Data Library has been produced in cooperation with the Japanese Nuclear Data Committee. In the new library, much emphasis is placed on the ...improvements of fission product and minor actinoid data. Two nuclear model codes were developed in order to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were carefully examined by considering experimental data or by the systematics of neighboring nuclei. Most of the fission cross sections were derived from experimental data. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. New evaluations were performed for the thirty fission-product nuclides that had not been contained in the previous library JENDL-3.3. The data for light elements and structural materials were partly reevaluated. Moreover, covariances were estimated mainly for actinoids. The new library was released as JENDL-4.0, and the data can be retrieved from the Web site of the JAEA Nuclear Data Center.
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