Ecological succession within lakes generally proceeds as eutrophication and shallowing occur and the aquatic biota of the lakes is altered. The eutrophication rate depends on the lake size and the area and fertility of the watershed. If the watershed fertility of several different lakes is equivalent and the lakes' formation time and initial environment are similar, the trophic status of each lake is expected to increase over time depending on the ratio of the watershed area to lake size. To test this supposition, we surveyed the topography and water quality of 10 lakes of varying sizes in Akan Caldera, Japan, which were formed thousands of years ago by fragmentation due to volcanic eruptions within the caldera. The ratio of the accumulated watershed area to lake size was positively correlated with total phosphorus concentration, an indicator of trophic status, and lake types were classified as oligotrophic, mesotrophic, eutrophic, and dystrophic. In addition, 21 species of macrophytes were found in the lakes, and the species composition of each lake was divided into five types corresponding to combinations of the lake types. The discovery of such diversity in a group of lakes with a similar origin paves the way for new comparative studies.

In clonal plant populations, a number of genetically identical ramets form a genet. While coexisting ramets potentially perform independently, their behaviours not only depend on ages and sizes but are also constrained by genetic background. In this study, genet dynamics and its variability among neighbouring genets were investigated based on the ramet demography of each genet in Convallaria keiskei . Genet dynamics were first formulated as a matrix model with the two components of clonal growth (clonal reproduction) and survival‐transitions between ramet size classes. Then, a statistical estimation of the matrix elements was established using three datasets: aboveground demographic censuses, belowground directional rhizome connections and genetic identification of ramets. Finally, genet growth rates reflecting both the changes of clonal growth and ramet size growth were estimated and compared for fundamental demographic elements among genets. Over three years of aboveground annual censuses of a 28 × 2 m plot, 2021 ramets were identified as belonging to 28 genotypes. Belowground excavation detected 515 clonal fragments. Genet growth rate of three dominant genets varied with medians of 1.13, 1.02 and 1.05; 95% credible intervals of the posterior distributions did not overlap between the genet with the largest median and the others. The variation was caused primarily by differences in clonal growth rather than survival‐transitions between size classes. Clonal growth by branching was rarer than at the tips but contributed to the maintenance of the genet. Therefore, both clonal growth frequencies and connecting patterns of ramets caused the variation of genet dynamics and established genets persist for a long time through the positive growth rates, which would contribute to maintain a population. We also conclude that fundamental demographic elements relating to clonal growth traits (the features of individual genets) strongly impact genet dynamics.

Plant Species BiologyVolume 37, Issue 6 p. 338-338 EDITORIAL Thank you and good-bye Masashi Ohara, Masashi Ohara orcid.org/0000-0003-3277-5743 Hokkaido University, Graduate School of Environmental Earth Science, Sapporo, JapanSearch for more papers by this author Masashi Ohara, Masashi Ohara orcid.org/0000-0003-3277-5743 Hokkaido University, Graduate School of Environmental Earth Science, Sapporo, JapanSearch for more papers by this author First published: 09 November 2022 https://doi.org/10.1111/1442-1984.12392Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume37, Issue6November 2022Pages 338-338 RelatedInformation

Akan Caldera lakes_1: Dataset of topography, water quality, and the number of species of macrophytes in the Akan Caldera lakes. Akan Caldera lakes_2: Diagram illustrating the classification of the watershed variables. Akan Caldera lakes_3: Correlation matrix of topography, water quality, and the number of species of macrophytes in the Akan Caldera lakes.

Many wild populations are suffering from the loss of genetic diversity caused by habitat fragmentation, while the degree of diversity loss differs among species and populations based on their life history characteristics. Trillium camschatcense, an understory perennial plant, has undergone intensive habitat fragmentation in the Tokachi region, Hokkaido, Japan. Although demographic deteriorations, such as reduced seed production, were already reported, genetic consequences of fragmentation have not been studied with reference to its life history. Here, we examined how life history events (e.g., growth and reproduction) and the stochasticity therein influence genetic diversity in two (each large and small) fragmented T. camschatcense populations. Genetic diversity was evaluated using genome-wide 2,008 single nucleotide polymorphisms (SNPs). In the small population, genetic diversity of newly germinated seedlings was significantly lower than that of matured life history stages, and effective number of breeders (N-b) was smaller than that of the large population. Simulations using a matrix population model showed that the diversity loss at seedlings is caused by genetic drift during reproduction, which was intensified by smaller N-b. Besides, simulations using randomly perturbed transition matrices suggested that stasis at juvenile stages, which is a common characteristics of T. camschatcense, maintains genetic diversity by buffering stochastic decrease, possibly contributing to population viability. While previous studies showed the importance to facilitate reproduction and recruitment for demographic recovery, this study highlighted the crucial roles of juvenile survival in terms of genetic diversity for the conservation of fragmented T. camschatcense populations in the Tokachi region.

Laportea bulbifera (Ulticaceae) is a monoecious plant that has a unique sexual expression: female flowers form on the upper part and male flowers on the lower part on an individual shoot. Therefore, for the seed reproduction, pollen needs to be transferred from the lower (male) to the upper (female) flowers. Our observations of male flowers confirmed that pollen was dispersed upward by "explosive wind pollination." A male flower has five stamens, and when the petals are open, the stamens are caught in a pistillode. With the growth of the stamens, they are released from the pistillode and then straightened with a spring-like movement of the filament. At the same time, the anthers dehisce, and the pollen is dispersed. The explosive release of pollen from the anthers and light wind in the habitat (forest edge or gap) contributes to wind pollination in L. bulbifera.

Predicting temporal dynamics of genetic diversity is important for assessing long-term population persistence. In stage-structured populations, especially in perennial plant species, genetic diversity is often compared among life history stages, such as seedlings, juveniles, and flowerings, using neutral genetic markers. The comparison among stages is sometimes referred to as demographic genetic structure, which has been regarded as a proxy of potential genetic changes because individuals in mature stages will die and be replaced by those in more immature stages over the course of time. However, due to the lack of theoretical examination, the basic property of the stage-wise genetic diversity remained unclear. We developed a matrix model which was made up of difference equations of the probability of non-identical-by-descent of each life history stage at a neutral locus to describe the dynamics and the inter-stage differences of genetic diversity in stage-structured plant populations. Based on the model, we formulated demographic genetic structure as well as the annual change rate of the probability of non-identical-by-descent (denoted as η). We checked if theoretical expectations on demographic genetic structure and η obtained from our model agreed with computational results of stochastic simulation using randomly generated 3,000 life histories. We then examined the relationships of demographic genetic structure with effective population size Ne, which is the determinants of diversity loss per generation time. Theoretical expectations on η and demographic genetic structure fitted well to the results of stochastic simulation, supporting the validity of our model. Demographic genetic structure varied independently of Ne and η, while having a strong correlation with stable stage distribution: genetic diversity was lower in stages with fewer individuals. Our results indicate that demographic genetic structure strongly reflects stable stage distribution, rather than temporal genetic dynamics, and that inferring future genetic diversity solely from demographic genetic structure would be misleading. Instead of demographic genetic structure, we propose η as an useful tool to predict genetic diversity at the same time scale as population dynamics (i.e., per year), facilitating evaluation on population viability from a genetic point of view.

Phenological overlap with pollinators is crucial for reproductive success in insect-pollinated plants. In this study, we examined whether pollinator visitation successfully occurred during an entire flowering season in two populations of the insect-pollinated spring ephemeral Trillium camschatcense in the Tokachi region of Hokkaido, northern Japan. We bagged flowers and excluded pollinator visitation during either the first or the last half of the entire flowering season to compare pollination success between the two periods. The two populations have experienced differing levels of climate warming in the last 60 years, which impacted pollinator visitation. In the population experiencing temperature rise more rapidly, fertilization rate and seed set decreased sharply when bagged during the first half period, indicating that pollinator visitation is skewed to the early part of the flowering season. The temporal skewness of pollination success would be an early warning signal of the impacts of climate warming on the reproductive success of T. camschatcense.

Trillium apetalon (4×) and T. tschonoskii (4×) hybridize commonly where both species grow sympatrically, leading to the formation of tetraploid T. miyabeanum in Hokkaido, Japan. The present study aimed to determine which isolation factor is responsible for the frequency and asymmetry of hybrid T. miyabeanum formation in a sympatric population of T. apetalon and T. tschonoskii. We examined the contributions and strengths of four reproductive isolation barriers of T. miyabeanum formation: flowering phenology, breeding system, genetic isolation, and hybrid inviability. In addition, we also investigated the effect of flowering phenology on reproductive success (i.e., seed production and outcrossing rates) and outputs (i.e., ovule production) for T. apetalon and T. tschonoskii. We calculated the absolute contribution of each isolation barrier to the total reproductive isolation and found that flowering phenology and differences in breeding systems between the two parental species were more effective when T. apetalon was the maternal parent. Furthermore, hybrids with T. apetalon as the maternal parent had lower viability than those of the reciprocal cross and did not reach the flowering stage. Particularly, absolute contribution of premating isolation, especially by flowering phenology and breeding system, was higher than that of other isolation factors for both crossing directions. For the formation of T. miyabeanum, we concluded that asymmetry of hybridization between T. apetalon and T. tschonoskii would be caused by strong premating isolations. The asymmetry of the isolating barriers may promote T. tschonoskii as the maternal parent of T. miyabeanum.

Classifying a variety of plant life histories is an important step to understand ecological and evolutionary background of life history diversification in plants. Principal component analysis (PCA) of life history traits, as well as elasticity analysis using a ternary diagram, successfully categorized the diverse life histories and clarified their link to various ecological characteristics, such as population dynamics, functional traits, and conservation status. However, the relationships with population genetic properties, including genetic diversity, have not been explored very much. In this study, we overlaid annual change rate of expected heterozygosity η on life history spectrum obtained by PCA and elasticity analysis to examine which life history strategy can maintain high genetic diversity over time. We found that η gradually changed along the fast-slow continuum and that slow-paced life histories maintained high genetic diversity, probably due to generation overlap. Elasticity analysis showed that life histories that highly depend on stasis also maintained genetic diversity. As genetic diversity reflects adaptive potential to environmental changes, our study provides a new genetic perspective on adaptative evolution and population viability to life history study.

Aegagropila linnaei is a unique freshwater green alga that develops into spherical aggregations known as “lake balls”, “Cladophora balls” or “Marimo”. Loss of this species is progressing globally, and there is concern over threats and its conservation. As part of the study which aims to conserve this endangered species, zoosporogenesis of A. linnaei in Lake Akan, designated as a Special Natural Monument of Japan, was investigated. Materials encompassing three growth forms of A. linnaei: "aggregative", "free-floating", and "epilithic", were collected at five sites around the lake at regular intervals from spring to autumn of 2017 and 2018. Quadriflagellate zoospores were observed at three sites (one aggregative and two epilithic) in mid-August and early September with a reproducibility, but not at two sites (one aggregative and one free-floating). Percentages of zoospore-producing filaments were extremely low (maximum 1.3 %), and the result of statistical analysis by generalized linear model showed no significant difference among the study sites and periods in both years. These results indicated that the zoosporogenesis of A. linnaei, which has been thought to be an extremely rare event in the past, occurs regularly even though being low percentage. Such rare zoosporogenesis appears to provide a few initials for the ensuing generations and to contribute to maintaining the aggregative form through the continuation of vegetative growth.

It is not feasible to continuously observe ecological succession in lakes because of the long time-scales generally involved. Thus, the process has been inductively deduced by comparing many lakes with different succession states, or indirectly simulated by tracking studies of smaller water bodies, experiments using microcosms or mesocosms, and reconstruction of lake history by sediment analysis. However, the reality of succession processes in large lakes with slow succession is not well understood, and new approaches are needed. Theoretically, in a group of large and small lakes of similar ages and with similar initial and watershed environments, the rate of nutrient accumulation in each lake depends on the ratio of watershed area to lake size, and the lakes are predicted to evolve to different trophic levels over time. Here, we tested this hypothesis on the 10 lakes of varying sizes in Akan Caldera, Japan, which were formed thousands of years ago by fragmentation due to volcanic eruptions within the caldera. Topographic and water quality studies showed that the ratio of accumulated watershed area to lake size (area and volume), expressed logarithmically, had a positive linear regression with the total phosphorus concentration, an indicator of trophic level. The trophic levels of the lakes were diverse, including oligotrophic, mesotrophic, and eutrophic types in the traditional “lake type” classification based on total phosphorus and chlorophyll-a concentrations. Furthermore, 21 species of aquatic macrophytes were observed by a diving survey, and the plant species composition was classified into five groups corresponding to the trophic status of the lakes, indicating a conventional “hydrarch succession”. The diversity of water quality and aquatic vegetation in a group of lakes with similar origins paves the way for new comparative studies of lakes, including large lakes.

Plant Species BiologyVolume 35, Issue 1 p. 4-5 EDITORIAL Plant Species Biology – Editorial Masashi Ohara, Masashi Ohara Editor-in-Chief Hokkaido University, JapanSearch for more papers by this author Masashi Ohara, Masashi Ohara Editor-in-Chief Hokkaido University, JapanSearch for more papers by this author First published: 09 January 2020 https://doi.org/10.1111/1442-1984.12263Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume35, Issue1January 2020Pages 4-5 RelatedInformation

The seed germination characteristics of Maianthemum dilatatum were investigated in a laboratory experiment and the results compared with those of other species in the subfamily Asparagoideae, LILIACEAE (Engler's system). M. dilatatum seeds mature in late September to October in montane to subalpine areas across Japan. Germination percentages and rates were low for fresh seeds at 10 to 30 degrees C. Seeds cold stratified for 4 months or longer showed increased germination percentages and rates. The seeds lost germinability with decreasing moisture content. The seeds germinated well in dark conditions. The process of germination from the cotyledonary sheath/petiole breaking through the seed coat to the appearance of the first and second leaves was examined. After emergence of the cotyledonary sheath/petiole, a root emerged from it, and additional roots appeared after 1-2 months. The plumule emerged from the cotyledonary sheath/petiole after the seedling had three roots. Seeds dispersed in autumn, and germinate slowly in the next spring after exposure to low temperature even though dark condition as buried seed. We compared the seed germination characteristics among species in the Asparagoideae or with other recent taxonomy, and found that seedlings of Paris verticillate and Trillium apetalon, which belong to Melanthiaceae, and Streptopus streptopoides Var. japonica and Clintonia udensis, which belong to Liliaceae (linear cotyledon), were different from Asparagaceae, showing a globose cotyledon in the APG II.

Dear colleagues First of all, I am happy and excited to announce that our journal Plant Species Biology has started a joint publication with two international journals, namely Ecological Research and Population Ecology, from January 2019. These three journals are representative international journals of ecology in Japan. Ecological Research, published by the Ecological Society of Japan since 1986, is the only journal from Asia that covers all the fields of ecology. Population Ecology, published by The Society of Population Ecology, has a longer history than Ecological Research, which was established in 1952 with the former name Researches on Population Ecology. The three major journals cover the research fields and objects of ecology in a complementary way, and the countries of authors also vary substantially (Figure 1). By conducting joint publication, we hope that readers of the world can gain more information on ecological studies delivered from Asia. On the new platform of Wiley, the three journals share a common portal page, as in the journal groups by the ESA (Ecological Society of America) and those by the BES (British Ecological Society). From the portal page, readers can choose journals they want to read, and manuscript authors can select the most suitable journals for submission by comparing the journal scope, objectives and recent papers. Furthermore, the editors of the three journals can recommend authors to transfer their manuscripts among three journals if a submitted manuscript matches better with the scopes and targets. The editorial offices of the three journals have also been incorporated into one system, which will lead to more efficient editorial procedures and to shorter waiting times for making decisions and publication. In 2018, we received manuscript submissions from 19 counties and successfully published 33 manuscripts. In addition, it is our honor to inform you that impact factor (IF) for our journal increased to 1.673. The rankings of ISI Journal Citation Reports 2017© were 91/222 (Plant Science) and 97/158 (Ecology). So, Plant Species Biology certainly keeps up to the standard level of international scientific journals. We will continue high-quality services for every paper in Plant Species Biology in 2019. Online Only: From 2015 (Issue 30), we published Plant Species Biology four times (January, April, July and October) per year by online only (without printed issues). Early View articles are complete full-text articles published online in advance of their publication in a printed issue. Articles are therefore available as soon as they are ready, rather than having to wait for the next scheduled print issue. Although Early View is available, we could publish the manuscripts more timely after acceptance (within 3 months after acceptance). Fast decision: Authors can submit manuscripts to Plant Species Biology online, through SCHOLARONE MANUSCRIPTS™. Safe, secure and easy to use, this system will help to reduce the time it takes to make an initial decision on your paper. For your information, average days from submission to first decision were 41 days in 2018. Our editorial teams, along with authors and reviewers, try to make possible the publication of a timely, attractive and informative journal. We also publish the articles of the awardees of the “Kataoka Prize”. The Kataoka Prize is established in the memory of Dr Masayuki Kataoka, a promising young ecologist who passed away in an unfortunate traffic accident in 1991. His premature death is a great loss to the field of plant sciences. The Kataoka Prize is run by a special fund donated by the family of the late Dr Kataoka. Now, we use the fund to promote and encourage young plant biologists in our society. In 2018 (Volume 33), we have published one paper contributed by Dr Yasuhiro Sato, entitled “Associational effects and the maintenance of polymorphism in plant defense against herbivores: review and evidence” (Sato, 2018). I am sure you will be impressed by this excellent contribution. The Society for the Study of Species Biology decided to give the Best Paper Award to excellent papers published in Plant Species Biology, judged to be the best in scientific importance, commencing in 2018. Two papers were selected as the Best Paper Award 2018, by the Editorial Committee of Plant Species Biology. One paper is “Pollination and reproduction of Psychotria homalosperma, an endangered distylous tree endemic to the oceanic Bonin (Ogasawara) Islands, Japan” contributed by Watanabe, Kato, Kuraya and Sugawara (2018, pp. 16–27). The other paper is “Flexible pollination system in an unpalatable shrub Daphne miyabeana (Thymelaeaceae)” contributed by Sakata and Nakahama (2018, pp. 239–247). Finally, I would like to introduce the editorial team of Plant Species Biology for 2019. The editorial committee members in 2019 are Drs Keiko Kitamura, Makoto Kato, Tsuyoshi Kobayashi, Teruyoshi Nagamitsu, Michiko Masuda, Atsushi Ushimaru, Takashi Miyake and Tamao Saito, and Ms Yuko Aoshima and Ms Terumi Kuhara also help us as editorial assistants. In addition, the eight editorial committee members, three staff members of Wiley, Ms Yukari Arao (Publishing Coordinator), Ms Eden P. Batol (Production Editor) and Ms Miyuki Hattori (ScholorOne Manuscripts Coordinator), help publish Plant Species Biology. Ms Emelita P. Rubano who supported our journal as Production Editor left the team due to resignation. We all would like to thank her for her kind and devoted support for Plant Species Biology, and we also welcome Ms. Eden P. Batol to our team as a new team member. We still do our best to maintain and enhance the quality, novelty and importance of papers published in Plant Species Biology, to maximize the usage, impact and value of our distinguished journal.

Cardiocrinum cordatum var. glehnii (Liliaceae) is a monocarpic perennial herb living in temperate broad-leaved deciduous forests. In the present study we examined the sizes (basal diameter of the stem and flower numbers) of flowering individuals and genetic diversity using microsatellite loci of 23 populations of C. cordatum var. glehnii in Hokkaido, Japan, over 2 years (2009 and 2010). As a result, we found both the basal stem diameter and the number of flowers varied widely among the populations. However, although the sizes of flowering individuals differed among the populations, these were very stable in each population and in each year. In addition, for genetic diversity, the same trends (i.e. wide variation among the populations but non-annual variation) were detected.

Because monocarpic perennial plants have only one reproductive opportunity in their entire life, they need to ensure offspring production. Some plants reproduce both sexually and vegetatively, and vegetative reproduction could possibly compensate for seed production. Therefore, the role and significance of these reproductive modes is likely to differ between monocarps and polycarps, which can reproduce many times. Cardiocrinum cordatum var. glehnii is a monocarpic perennial that reproduces both sexually and vegetatively (bulblet formation). Here, we investigated the characteristics and contribution to population maintenance of sexual and vegetative reproduction to reveal the significance of these two reproductive modes in this species. First, we found that bulblet formation occurred in plants after the three-leaved rosette stage. Second, resource allocation experiments revealed that although resources were mainly invested in fruit maturation after the flowering season, resource allocation was switched from sexual reproduction to vegetative reproduction if seed production was insufficient. Third, the outcrossing rate in this species varied greatly according to the environment surrounding the population. However, reproductive assurance by selfing kept seed production stable even if flowers did not receive sufficient pollen for full seed set via outcross pollination, and moreover, there was no intensive inbreeding depression. Finally, genotypic identification of ramets suggested that daughter ramets derived from vegetative reproduction received the space that the mother flowering ramet had occupied until the previous year.

Reproductive systems are recognized as having a profound influence on the extent and structure of genetic variation in plant populations. To investigate the spatiotemporal variation in the reproductive modes (sexual and vegetative reproduction) and population genetic structures of a monocarpic perennial herb, Cardiocrinum cordatum (liliaceae), we selected a variety of habitats (e.g. large forested area including primeval forest, small fragmented secondary forest, and so on) around Sapporo City, Japan. We conducted breeding experiments, monitored the fate and growth of marked individuals for 3years, and also analyzed the spatiotemporal genetic variation of flowering plants within the populations using allozyme variation. Plants emasculated prior to anthesis produced mature fruits in all populations examined. However, seed production was significantly lower in the small fragmented populations, possibly because of the low availability of pollinators and subsequent pollen limitation. In these fragmented populations, the mature flowering plants tended to be more dependent on vegetative reproduction for their recruitment, because they can only produce flowers once in their lifetime. Genetic diversity using samples from mature flowering plants in each population was lower in the small fragmented populations than in the large populations. In addition, although genotypic compositions in the fragmented populations were more or less similar during the 3years of the study, the dominant genotypes changed temporally and spatially every year in the large populations. The present study demonstrated that the reproductive features of C. cordatum can be altered in various environmental conditions, such as habitat fragmentation, and these changes considerably affected the population genetic structures and vice versa.

Plants that are consumed by herbivores incur a reduction in fitness. Therefore, plants need to prepare to defend against and/or avoid herbivory using resistance' and/or tolerance' systems. Phengaris teleius is a specialist herbivore of Sanguisorba tenuifolia. Phengaris teleius lays eggs in the flower buds of S. tenuifolia and the larvae of P. teleius feed on the ovaries and ovules of S. tenuifolia. In order to clarify the extent of herbivory damage by P. teleius and effect on reproduction in S. tenuifolia, we conducted field observations and artificial cutting experiments carried out in the natural habitat where both P. teleius and S. tenuifolia live sympatrically. Phengaris teleius often lays one egg per spike, and about half of the total eggs were laid on the spike that developed at the shoot apex and was largest in size. The fruits were damaged most heavily in the spike in which an egg was laid. However, the number of fruits was almost the same between individuals with no damage and individuals with a feeding damage rate of 40% or less. This showed that compensation would be achieved by increasing the number of fruits in other spikes without damage. On the other hand, because no compensation was detected in the cutting experiments, it was considered that compensation may be induced by biological stimuli produced by P. teleius. These responses may be one of the mechanisms for continuing the interspecific relationship between S. tenuifolia (host plant) and P. teleius (herbivore insect).