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PREMISE: The formation of isolated montane geography on islands promotes evolution, speciation, and then radiation if there are ecological changes. Thus, investigating evolutionary histories of montane species and associated ecological changes may help efforts to understand how endemism formed in islands' montane floras. To explore this process, we investigated the evolutionary history of the Rhododendron tschonoskii alliance, which grows in montane environments of the Japanese archipelago and the Korean Peninsula. METHODS: We studied the five species in the R. tschonoskii alliance and 30 outgroup species, using genome-wide single-nucleotide polymorphisms and cpDNA sequences, in association with environmental analyses. RESULTS: The monophyletic R. tschonoskii alliance diverged since the late Miocene. Species in the alliance currently inhabit a cold climatic niche that is largely different from that of the outgroup species. We observed clear genetic and niche differentiations between the taxa of the alliance. CONCLUSIONS: The association of the alliance's evolution with the formation of cooler climates on mountains indicates that it was driven by global cooling since the mid-Miocene and by rapid uplift of mountains since the Pliocene. The combination of geographic and climatic isolation promoted high genetic differentiation between taxa, which has been maintained by climatic oscillations since the Quaternary.

DOI： 10.1002/ajb2.16166

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DOI： 10.1111/1442-1984.12383

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.pld.2020.12.009

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Geographic and environmental isolations of islands and the mainland offer excellent opportunity to investigate colonization and survival dynamics of island populations. We inferred and compared evolutionary processes and the demographic history of Rhododendron tsusiophyllum, in the Izu Islands and the much larger island Honshu, treated here as the mainland, using thousands of nuclear SNPs obtained by ddRAD-seq from eight populations of R. tsusiophyllum and three populations of R. tschonoskii as an outgroup. Phylogenetic relationships and their habitats suggest that R. tsusiophyllum had evolved and migrated from cold north to warm south regions. We detected clear genetic divergence among populations in three regions of Honshu and the Izu Islands, suggesting restricted migration between them due to isolated habitats on mountains even in the mainland. The three regions have different changes in effective population size, especially, genetic diversity and population size of the Izu Islands are small compared to the others. Further, habitats of populations in the Izu Islands are warmer than those in Honshu, suggesting that they have undergone adaptive evolution. Our study provides evidences of montane rather than insular isolation on genetic divergence, survival of populations and significance of adaptive evolution for island populations with small population size and low genetic diversity, despite close proximity to mainland populations.

DOI： 10.1038/s41437-021-00417-w

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We investigated the clonal structure, self-incompatibility, and number of seeds per fruit in <italic>Camellia rusticana</italic>, a Japanese endemic species, in comparison to the closely related <italic>C. japonica</italic>. Clonal propagation was more vigorous in <italic>C. rusticana</italic> than in <italic>C. japonica</italic> and the clonal structure of <italic>C. rusticana</italic> varied among populations. <italic>C. rusticana</italic> can maintain genets for extended periods, even in harsh environments such as high-altitude areas with considerable snow accumulation, because even a single surviving genet can propagate clonally. However, sexual reproduction (<italic>i.e.</italic>, reproduction by seed) is advantageous for dispersal to distant suitable habitats. An artificial crossing test revealed high self-incompatibility in <italic>C. rusticana</italic>, as observed in <italic>C. japonica</italic>. In addition, the number of seeds per fruit was lower in <italic>C. rusticana</italic> than in <italic>C. japonica</italic>. Self-incompatibility in <italic>C. rusticana</italic> may play a role in production of high-quality seed, despite low seed production.

DOI： 10.2478/sg-2021-0011

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To manage biological invasions effectively, the impacts of alien species on the demography and traits of native species must be known, but determining those impacts can be challenging. We used a comparative approach to gain insight into the impacts that an alien toad (Bufo japonicus formosus) might have on native Japanese predatory amphibians. We compared the susceptibility of native predator species to alien toad toxins in the alien-invaded range and the susceptibility of closely related native predator species to the toxins in the alien toad's native range to investigate the impacts of an alien on a native species. Bufo japonicus formosus is native to Honshu, but was recently introduced to Hokkaido and Sado. In laboratory experiments, we compared individual mortality of predators exposed to a toad hatchling between novel predators on the toad-invaded islands and ecologically similar congeneric or conspecific species on Honshu, where the toad is native. We also compared (1) the percentage of individuals that consumed a toad hatchling and (2) toxin resistance (i.e. survival and growth of individuals after toad consumption) between these two groups of predators, as mechanistic components behind the susceptibility of the predators to the toxic prey. The mortality of Rana pirica from all populations after consumption of a toad hatchling was almost 100%, and that of Hynobius retardatus ranged from 14 to 90%, depending on the population. In contrast, the mortality of Rana ornativentris and Hynobius nigrescens was near 0% regardless of population. These differences between congeneric predators were mostly due to differences in their toxin resistance. These results suggest that the alien toad is a potential threat to the novel amphibian predators on Hokkaido, although they also imply that the novel predators on Hokkaido have the potential to develop toxin resistance through adaptive evolution. However, this counteradaptation may have a higher chance of evolving in H. retardatus than in R. pirica because of differences in their genetic backgrounds.

DOI： 10.1111/fwb.13417

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Three new taxa, Rhododendron sohayakiense Y.Watan. & T.Yukawa (Ericaceae), and its two varieties, var. kiusianum Y.Watan., T.Yukawa & T.Minamitani and var. koreanum Y.Watan. & T.Yukawa are described and illustrated from Japan and South Korea. They can be distinguished from each other and from the other members of the R. tschonoskii alliance, i.e. R. tschonoskii, R. tetramerum, R. trinerve and R. tsusiophyllum, through their combination of leaf size, leaf morphologies including lateral nerves on abaxial leaf surface, corolla morphologies including number of corolla lobes, style length and anther form. Phylogenetic inferences based on chloroplast DNA and genome-wide sequences revealed that each of the three new taxa is monophyletic and they further form a clade. Distributions of the three taxa are also clearly separated from each other and also from the other members of the R. tschonoskii alliance.

DOI： 10.3897/phytokeys.134.38216

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How phenotypic or genetic diversity is maintained in a natural habitat is a fundamental question in evolutionary biology. Flower color polymorphism in plants is a common polymorphism. Hepatica nobilis var. japonica on the Sea of Japan (SJ) side of the Japanese mainland exhibits within population flower color polymorphism (e.g., white, pink, and purple), while only white flowers are observed on the Pacific Ocean (PO) side. To determine the relationships between flower color polymorphism, within and among populations, and the genetic structure of H. nobilis var. japonica, we estimated the genetic variation using simple sequence repeat (SSR) markers. First, we examined whether cryptic lineages corresponding to distinct flower colors contribute to the flower color polymorphisms in H. nobilis var. japonica. In our field observations, no bias in color frequency was observed among populations on Sado Island, a region with high variation in flower color. Simple sequence repeat (SSR) analyses revealed that 18% of the genetic variance was explained by differences among populations, whereas no genetic variation was explained by flower color hue or intensity (0% for both components). These results indicate that the flower color polymorphism is likely not explained by cryptic lineages that have different flower colors. In contrast, populations in the SJ and PO regions were genetically distinguishable. As with the other plant species in these regions, refugial isolation and subsequent migration history may have caused the genetic structure as well as the spatially heterogeneous patterns of flower color polymorphisms in H. nobilis var. japonica.

DOI： 10.1007/s10265-016-0893-1

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To determine the effect of disturbance on clonal structures of natural forest of <i>Cryptomeria japonica</i>, we have investigated spatial distribution and size structure of this species in two forests. We have set up two plots, the first one is disturbed by typhoon while another one is not affected by typhoon disturbance, and investigated the clonal structure using SSR markers. We found three types of clonal structure: (a) gathered and middle size ramets, (b) apart and different size ramets, and (c) many small ramets in line. The (a) and (b) are thought to be layering clones from withdrawn juvenile or bud by heavy snow pressure. The (c) were buds from an uprooted individual by typhoon disturbance. The result suggests that typhoon disturbance and snow pressure are one of the factors to form different clonal structures.

DOI： 10.4005/jjfs.97.19

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Ecological observation of surviving organisms and their interactions during and after volcanic activity provides an indispensable opportunity to study how organisms respond to environmental devastation. Eurya japonica satisfies the criteria as a facilitator plant species in recovering forest on the volcanic Miyake Island, which erupted in 2000, because this species is more resistant to volcanic gases than other tree species on the island. We examined the effects of volcanic disturbance on reproductive success of E. japonica and compared the visitation frequencies of pollinator insects and frugivorous birds at nine sites showing different degrees of disturbance. The leaf health was strongly decreased by frequent volcanic gas exposure, whereas flower bud formation was not suppressed. The fruit abortion rate did not differ among sites, whereas the fruit set rate significantly decreased with increasing volcanic damage. The frequencies of pollinator and frugivorous bird visits were higher in heavily damaged areas. These results indicate that the pollination and seed-dispersal system of E. japonica was potentially maintained under volcanic disturbance, though the final reproductive success decreased.

DOI： 10.1007/s11258-014-0393-0

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Observations of interspecies interactions during volcanic activity provide important opportunities to study how organisms respond to environmental devastation. Japanese camellia (Camellia japonica L.) and its main avian pollinator, the Japanese White-eye (Zosterops japonica), offer an excellent example of such an interaction as key members of the biotic community on Miyake-jima, which erupted in 2000 and continues to emit volcanic gases. Both species exhibit higher resistance to volcanic damage than other species. We examined the effects of volcanic activity on this plant-pollinator system by estimating pollen flow and the genetic diversity of the next generation. The results showed that despite a decrease in Camellia flowers, the partitioning of allelic richness among mother-tree pollen pools and seeds decreased while the migration rate of pollen from outside the study plot and the pollen donor diversity within a fruit increased as the index of volcanic damage increased. In areas with low food (flower) density due to volcanic damage, Z. japonica ranged over larger areas to satisfy its energy needs rather than moving to areas with higher food density. Consequently, the genetic diversity of the seeds (the next plant generation) increased with the index of volcanic damage. The results were consistent with previously published data on the movement of Z. japonica based on radio tracking and the genetic diversity of Camellia pollen adhering to pollinators. Overall, our results indicated that compensation mechanisms ensured better pollination after volcanic disturbance.

DOI： 10.1371/journal.pone.0062696

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Premise of the study: Nuclear microsatellite primers were developed to analyze the clonal diversity and population genetic structure of the endemic polyploid herb Callianthemum miyabeanum.Methods and Results: Using a protocol for constructing microsatellite-enriched libraries, 15 primer sets were developed for use in C. miyabeanum. The number of alleles found ranged from five to 22. The estimated range of expected heterozygosities was 0.574 to 0.907, and the Shannon-Weiner diversity index ranged from 1.061 to 2.733. Cross-amplification of all loci was also successful in the closely related endemic species C. kirigishiense and C. hondoense.Conclusions: The development of these microsatellite loci will facilitate a deeper understanding of the genetic diversity, mode of reproduction, and population structure of not only C. miyabeanum, but also the other Callianthemum species endemic to Japan.

DOI： 10.3732/ajb.1200202

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Menziesia goyozanensis, a Japanese kind of fool's huckleberry, is a shrub species endemic only to Mt. Goyo in northern Japan. This species is listed as 'critically endangered' in the Red Data Book of wild plants in Japan, and only a single population has yet been discovered. We isolated and characterized 16 microsatellite loci for this species. The number of alleles ranged from 2 to 25. The range of expected heterozygosities was 0.292-0.917. Five of the 16 microsatellites were not conformed to Hardy-Weinberg equilibrium, probably due to the restricted population size, genetic drifting and the presence of null alleles. These 16 microsatellite loci gave a combined non-exclusion probability of < 1.65E-15 in the sampled population. In Menziesia pentandra, which is closely related species to M. goyozanensis, the number of alleles detected and the expected heterozygosities of twelve loci ranged from 3 to 19 and 0.536 to 0.966, respectively. These informative microsatellite markers will be useful in studies of population genetic structure for these species.

DOI： 10.1007/s12686-011-9406-7

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In nature, spatiotemporally dynamic coevolutionary processes play major roles in the foundation and maintenance of biodiversity. Here, we examined the arms race coevolution involving a seed-eating weevil with a long snout and its camellia plant host with a thick fruit coat (pericarp) throughout the marked climatic gradient observed across the Japanese islands. Results demonstrated that female weevils, which bored holes through camellia pericarps to lay eggs into seeds, had evolved much longer snouts than males, especially in areas in which Japanese camellia pericarps were very thick. The thickness of the plant pericarp was heritable, and the camellia plant evolved a significantly thicker pericarp on islands with the weevil than on islands without it. Across populations with weevils, resource allocation to plant defense increased with increasing annual mean temperature or annual precipitation, thereby geographically differentiating the evolutionary and ecological interactions between the two species. Given that the coevolutionary relationship exhibited appreciable variation across a relatively small range of annual mean temperatures, ongoing global climatic change can dramatically alter the coevolutionary process, thereby changing the ecological interaction between these species.

DOI： 10.1086/659624

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：The Ecological Society of Japan  

DOI： 10.18960/seitai.61.2_185

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG TOKYO  

DOI： 10.1007/978-4-431-53901-8_5

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Volcanic activity provides an indispensable opportunity to study the ecological responses of organisms to environmental devastation. We examined the reproductive success of Camellia trees to identify how volcanic activity affects the processes of leaf survival, flowering activity, fruit and seed production, pollinator abundance, pollinator visitation frequency, pollination rate, and fruit and seed maturation at different damage sites on Miyake-jima, which experienced an eruption in the summer of 2000. Volcanic gases negatively affect leaf survival and reduce flowering activity in heavily damaged areas. Pollen transfer was sufficient to ensure that higher pollination rates (83%) occurred in heavily damaged areas than in less damaged areas (26-45%), but pollinator densities were lower in response to reduced flower resources. Fruit abortion rates were greater in heavily damaged sites (78%) than in less-damaged sites (53-63%). Consequently, fruit-set rates (16-29%) did not differ significantly among sites. Seed set rates tended to increase with increasing volcanic damage. The negative correlation between seed-set rates and seed mass suggests that the decreased seed mass in severely damaged sites was attributable to the better pollination rates observed there. These results indicate that compensation mechanisms ensure better reproductive success at sites that are more strongly affected by volcanic activity.

DOI： 10.1007/s11284-007-0345-4

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Seed dispersal determines a plant's reproductive success, range expansion, and population genetic structures. Camellia japonica, a common evergreen tree in Japan, has been the subject of recent genetic studies of population structure, but its mode of seed dispersal has been assumed, without detailed study, to be barochory. The morphological and physiological features of C. japonica seeds, which are large and nutritious, suggest zoochorous dispersal, however. We compared actual distances between mother trees and seedlings with distances attributable to gravity dispersion only, to test the zoochory hypothesis of C. japonica. The animals that transport the seeds for caching were identified experimentally. We also examined the extent to which seed dispersal is affected by the behavior of animal vectors. Seed dispersal by Apodemus speciosus was confirmed by taking photographs of animals that were consuming seeds experimentally deposited on the ground. Camellia seeds hoarded by the rodents under the litter or soil were protected from drying. On the basis of microsatellite analysis of maternal tissue from the seed coat, the mother trees of 28 seedlings were identified. Maternity analysis revealed the average seed-dispersal distance from mother trees was 5.8 m +/- 6.0 SD, a distance greater than initial dispersal by gravity alone. These results indicate that C. japonica is a zoochorous species dispersed by A. speciosus. Fifty percent of the seed dispersal occurred from mature evergreen forests to dwarf bamboo thickets. This directional seed dispersal would contribute to range expansion of C. japonica. Home range sizes of A. speciosus were 0.85 ha at most and covered with different types of vegetation, from evergreen forests to grassland. This low specificity of their microhabitat use might enhance seed dispersal to different types of vegetation.

DOI： 10.1007/s11284-006-0179-5

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DOI： 10.11519/jfsc.131.0_384

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DOI： 10.11519/jfsc.130.0_281

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DOI： 10.11519/jfsc.130.0_424

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DOI： 10.11519/jfsc.129.0_50

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DOI： 10.11519/jfsc.128.0_710

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DOI： 10.11519/jfsc.127.0_671

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本研究では伊豆諸島におけるヤブツバキの繁殖システムについて統合的な理解を図るために、花粉媒介における生物間相互作用について、花粉の遺伝的多様性に注目した検証を行った。&lt;br&gt;&lt;br&gt; 調査地である三宅島は、2000年から続く火山活動により、森林は破壊的な影響を受けている。しかし、森林を構成する樹種は火山ガスに対する耐性が異なっており、主要な構成種であるヤブツバキは、火山ガスに対する耐性が高く、展葉や開花活動が行われている。一方ヤブツバキの受粉に関与する鳥類（主にメジロ）は、ヤブツバキとは異なる影響を被っていると考えられる。そのため、花粉媒介における生物間相互作用系のモデルとして、三宅島内の火山活動の質が異なる複数地点において、ヤブツバキ（生存率、着葉率、葉の食害率、開花率、樹木あたりの開花数、結果率）と花粉媒介者の生息密度調査を行ってきた。&lt;br&gt;&lt;br&gt; この結果、火山活動の質が異なる複数地点では樹木あたりの開花数が異なっており、それに正比例して花粉媒介者の生息密度が高くなることが明らかになった。そのため、開花数の少ないところでは、花粉媒介者の密度が低下しているために結果率が下がると考えられたが、結果率の調査の結果では、開花数の少ないところで逆に結果率が高くなっていた。しかしながら、たとえ噴火による開花率と花粉媒介者の密度の低下が、種子の受粉率を低下させないとしても、花粉の遺伝的多様性には何らかの影響を与えている可能性が考えられる。&lt;br&gt;&lt;br&gt; そこで、まずは個体群間における開花密度の違いが花粉媒介者の生息密度とヤブツバキの繁殖成功に与える影響を検証するために、隣島である新島において、開花密度の異なる個体群間で結実率と花粉の遺伝的多様性の比較を行った。さらに噴火による被害程度の異なるヤブツバキ個体群間においても、花粉の遺伝的多様性について検証をおこなった。&lt;br&gt;

DOI： 10.14848/esj.ESJ51.0.688.0

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Publisher：ECOLOGICAL SOCIETY OF JAPAN  

ヤブツバキの有力な花粉媒介者であるメジロ（Kunitake et al., in press）は、冬期の餌資源としてヤブツバキの花蜜に大きく依存している（国武・長谷川、未発表）。そこで、両者の相互依存性がどの程度の強さなのかを明らかにするために、メジロの個体群密度に対するヤブツバキの花資源量の影響評価を試みた。&lt;br&gt;&lt;br&gt; 1995年以来、我々は伊豆諸島の新島において、厳冬期におけるメジロの個体数とヤブツバキの開花数、及び繁殖期におけるメジロのさえずり個体数をモニタリングしてきた。2000年から2003年には、島の一部でトビモンオオエダシャクの大発生が続き、局地的にヤブツバキの開花がみられない地域が生じた。さらに、三宅島においては、2001年以後、噴火の影響程度が異なる地点でメジロとヤブツバキの生息・生育状況についてセンサスを行った。これらのデータセットを用いて、ヤブツバキの開花数がメジロの冬期個体数密度に及ぼす影響とメジロの冬期個体数密度と繁殖期におけるさえずり個体数の関係について解析を行い、以下の結果を得た。&lt;br&gt;&lt;br&gt;１） 新島では、エダシャクの大発生が起きる前までは、島内に設置した3ヶ所においてメジロの冬期個体数は同調して年変化を示したが、発生後は、エダシャクの発生地域でのみメジロの個体数が減少した。&lt;br&gt;&lt;br&gt;２） エダシャクによる食害程度が異なる10ヶ所において、ヤブツバキの開花個体密度とメジロの個体数は有意な正の相関を示した。&lt;br&gt;&lt;br&gt;３） 三宅島において、メジロの冬期生息密度とヤブツバキの個体当たりの開花数は正の相関を示し、ヤブツバキの花が多い場所ほどメジロの生息密度が高かった。&lt;br&gt;&lt;br&gt;４） 新島において、メジロのさえずり個体数密度は、冬期個体数密度によって左右されたが、冬期個体数密度には影響を与えていなかった。&lt;br&gt;&lt;br&gt; 以上の結果から、メジロの個体数密度は、ヤブツバキの花資源量に大きく規定されていることが明らかにされた。&lt;br&gt;

DOI： 10.14848/esj.ESJ51.0.687.0

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Publisher：The Japanese Forestry Society  

The role of <I>Apodemus speciosus</I> in the seed dispersal of <I>Camellia japonica</I> was investigated in an abandoned vegetable field adjacent to an evergreen broad-leaved forest. Seed dispersal by <I>A.speciosus</I> was confirmed by taking photographs of animals that were bringing seeds experimentally deposited on the forest floor. <I>Camellia</I> seeds hoarded by the soil were protected from drying. Mother trees of 28 seedlings were identified by examining multilocus genotypes of microsatellite DNA loci. Distance of seedlings from the nearest mature tree was significantly positively correlated with the actual dispersal distance of seeds from mature trees as revealed by DNA analysis. Seeds were dispersed from 0m to 29m with an average 5.79m(5.96SD). Moreover, 54% of seeds were dispersed from mother trees in the nearby evergreen broad-leaved forest to the area of successional stage rather than around the mother trees in the forest. These results suggest that seed dispersal by <I>A.speciosus</I> contribute to expand distribution of <I>Camellia japonica</I>.

DOI： 10.11519/jfs.115.0.P5060.0

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J-GLOBAL

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