Ecological Research


    Vol. 31 (2016)
    Submitted: 469
    Accepted: 98


    Current issue (vol. 32, issue 2)
    Days for acceptance:
    144 (37–293)
    Days for online-first:
    158 (50–308)
    Days for publication:
    209 (90–375)


  • The 20th MIYADI AWARD

  • Individual interaction data are required in community ecology: a conceptual review of the predator-prey mass ratio and more

    Takefumi Nakazawa

    Ecological Research vol 31, issue 3, pp. 289–305

    Keywords: Allometry; Individual interaction; Life-history stage; Ontogenetic niche shift; Size structure

    Abstract nakazawa_2016Community ecology is traditionally species-based and assumes that species comprise identical individuals. However, intraspecific variation is ubiquitous in nature because of ontogenetic growth and critical in food-we dynamics. To understand individual interaction-mediated food webs, researchers have recently focused on body size as the most fundamental biological aspect and assessed a parameter called the predator-prey mass ratio (PPMR). Herein, I review the conceptual development of the PPMR and suggest four major concerns regarding its measurement: (1) PPMR should be measured at the individual level because species-averaged values distort actual feeding relationships, (2) individual-level PPMR data on gape-unconstrained predators (e.g., terrestrial carnivores) are limited because previous studies have targeted gape-limited fish predators, (3) predators' prey size selectivity (preferred PPRM) is conceptually different from dietary prey size (realized PPMR) and should be distinguished by incorporating environmental prey abundance information, and (4) determinants of preferred PPMR, rather than those of realized PPMR, should be identified to describe size-dependent predation. Future studies are encouraged to explore not only predation but also other interaction types (e.g., competition, mutualism, and herbivory) at the individual level. However, this is not likely to occur while ecological communities are still considered to be interspecific interaction networks. To resolve this situation and more comprehensively understand biodiversity and ecosystem functioning, I suggest that community ecology requires a paradigm shift in the unit of interaction from species to individuals, similar to evolutionary biology, which revolutionized the unit of selection, because interactions occur between individuals.

    Takefumi Nakazawa is the recipient of the 20th Denzaburo Miyadi Award!!

  • The 19th MIYADI AWARD

  • Genome-wide population genetic analysis identifies evolutionary forces establishing continuous population divergence

    Yuma Takahashi

    Ecological Research

    Keywords: Balancing selection; Cline Damselfly; Divergent selection; Stochastic factor

    Abstract Elucidating the mechanism shaping the spatial variations of traits has long been a central concern of evolutionary biologists. Geographic clines of allele/morph frequencies along environmental gradients are suggested to be established and maintained by the balancing of two opposing evolutionary forces, namely selection that generates spatial differentiation in morph frequencies, and selection and/or stochastic factors that lead to the coexistence of multiple morphs within a population. Thus, testing for both selection and stochastic factors is necessary for a comprehensive understanding of the mechanism underlying clinal variation in morph/allele frequency in natural populations. Here, I identified the evolutionary forces responsible for clinal variation of color morph frequency in Ischnura senegalensis by comparing the population divergence of putatively neutral loci generated by high-throughput next-generation sequencing (F[STn]) with that of the putative color locus (F[STc]). No strong correlation was observed between F[STn] and F[STc], suggesting that stochastic factors contribute less to color-locus population divergence. F[STc] was less than FSTn between populations exposed to similar environmental conditions, but greater than F[STn] between populations exposed to different environmental conditions, suggesting that both balancing selection and divergent selection act on the color locus. Therefore, two antagonistic selection factors rather than stochastic and historical factors contribute to establishing the clinal variation of morph frequency in I. senegalensis.

    Yuma Takahashi is the recipient of the 19th Denzaburo Miyadi Award!!

  • The 2nd SUZUKI AWARD

  • Semantic communication in birds: evidence from field research over the past two decades

    Toshitaka N. Suzuki

    Ecological Research Vol. 31, Issue 3, pp 307–319

    Keywords: Alarm call; Bird; Communication; Functionally referential; Semantic communication

    Abstract What do animal signals mean? This is a central question in studies on animal communication. Research into the semantics of animal signals began in 1980, with evidence that alarm calls of a non-human primate designated predators as external referents. These studies have challenged the historical assumption that such referential signaling is a unique feature of human language and produced a paradigm shift in animal communication research. Over the past two decades, an increasing number of field studies have revealed similar complexity in anti-predator communication of birds. The acoustic structures of avian alarm calls show a high degree of variation in pitch, duration, shape, and repetition rate. In addition to such distinct and graded variations, several birds combine discrete types of notes or calls into higher complex sequences. These variations in alarm calls are typically associated with the predator' s attributes, such as predator type and distance, and receivers respond to them with appropriate anti-predator behaviors. Although alarm calls of several bird species, as well as those of monkeys, appear to denote predator attributes, almost nothing is known about the cognitive processes that underlie the production and perception of these signals. In this review, I explore the existing evidence for referential signaling in birds and highlight the importance of the cognitive approach to animal communication research. I hope this review will promote further investigations of alarm-calling behavior in birds and will help enhance our understanding of the ecology and evolution of semantic communication.

    Toshitaka N. Suzuki is the recipient of the 2nd Suzuki Award!!


  • Possible ideas on carbon and nitrogen trophic fractionation of food chains: a new aspect of food-chain stable isotope analysis in Lake Biwa, Lake Baikal, and the Mongolian grasslands

    Eitaro Wada, Reiichiro Ishii, Maki Noguchi Aita, Nanako O. Ogawa, Ayato Kohzu, Fujio Hyodo & Yoshihiro Yamada

    Ecological Research vol.28, issue 2, pp.173–181

    Keywords: Δ15N–δ13C relationship; Food chain; Lake Biwa; Lake Baikal;Mongolian grassland

    Abstract Trophic fractionation of carbon and nitrogen isotopes (Δδ13C, Δδ15N) was examined using previously complied databases for food chains in Lake Biwa, Lake Baikal, and Mongolian grassland. The following two features were clarified: (1) For each ecosystem, the ratios of trophic fractionation of carbon and nitrogen isotopes (Δδ15N/Δδ13C) throughout food chain could be obtained as the slope of linear regression line on the δ15N–δ13C plot. (2) Further, analysis of covariance (ANCOVA) revealed the slopes on 15N–δ13C were not significantly different among these various ecosystems and allowed us to have the regression by setting δ15N as the response variable: δ15N = 1.61 δ13C + [ecosystem specific constant] with standard errors of [±0.41] and [±9.7] for the slope and the intercept, respectively. It was suggested that the slope of the regression (or the ratio Δδ15N/Δδ13C) could be applicable to more complicated food webs in case nitrogen and carbon isotope ratios of primary producers can be assumed constant in space and time within the ecosystems. The results from simple linear regression analyses coincided well with the ANCOVA results for these ecosystems, although there was some discrepancy between the results of the two statistical analyses. Possible factors that govern the linear relationship between δ15N and δ13C along a food chain are discussed together with a new scope for the stable isotope food chain analyses.

    Eitaro Wada is the recipient of the 7th Ecological Society of Japan Award!!

  • The 6th OSHIMA AWARD

  • Effects of wind and thermal conditions on timberline formation in central Japan: a lattice model

    Koichi Takahashi

    Ecological Research vol.29, issue 2 pp. 121–131

    Keywords: Climatic change; Global warming; Lattice model; Timberline; Treeline

    Abstract The upper distribution limit of tall tree species Abies mariesii is the timberline in central Japan, and dwarf pine Pinus pumila dominates above the timberline to near the summit. My previous studies suggested that the main cause of the timberline formation is the increase in mortality due to strong wind in winter rather than low growth due to low summer temperature. This study evaluated how wind velocity affects timberline formation and if the altitude of timberline moves upward due to high thermal conditions, by using a lattice model. Increase in wind velocity throughout the altitude lowered the altitudes of upper distribution limits of the two species. On the contrary, prolonged growth period due to high thermal conditions increased the upper distribution limit of P. pumila, and the upper distribution limit of A. mariesii was hardly affected by the change of growth period. However, the upward shift of the upper distribution limit of P. pumila due to the prolonged growth period in the model would not be realistic because P. pumila had already distributed up to near the summit. This study concludes that A. mariesii is a superior competitor to P. pumila at low altitudes with low wind velocity, but dwarf pine P. pumila can dominate at higher altitudes because A. mariesii suffers severe mechanical damage due to strong wind in winter, and that the altitude of the timberline does not move upward even under high thermal conditions due to global warming.

    Koichi Takahashi is the recipient of the 6th Oshima Award!!

  • Costs and constraints in aphid-ant mutualism

    Izumi Yao

    Ecological Research vol. 29, issue 3, pp. 383–391

    Keywords: Aphid-ant mutualisms; Cost of ant attendance; Honeydew; Dispersal; Flight apparatus

    Abstract While many studies have demonstrated that ants provide beneficial services to aphids, Bristow (Ant-plant interactions, Oxford University Press, Oxford, 104–119, 1991) first questioned why so few aphid species are ant-attended. Phylogenetic trees have demonstrated multiple gains and loss of ant-attendance in the course of aphid-ant interactions, implying that mutualisms easily form and dissolve. Several studies have reported the factors that influence the formation and maintenance of aphid-ant interactions. Examples include the physiological costs of ant attendance, competition for mutualistic ants, ant predation on aphids, the influence of host plants, and parasitoid wasps. Recent physiological techniques have also revealed the chemical component of aphid-ant mutualisms. The honeydew of ant-attended aphids contains melezitose (a trisaccharide), which has an important role in aphid-ant interactions. Studies of cuticular hydrocarbons on aphids and ants have clarified the underlying mechanisms of ant predation on aphids. Attending ants also reduce aphid dispersal ability, causing the formation of fragmented aphid populations with low genetic diversity in each population. The reduced aphid dispersal could be partly explained by higher wing loading and reduction of flight apparatus due to ant attendance. Whether ant attendance is associated with the range of host plants of aphids or genetic variation in microorganism in aphids remain to be explored.

    Izumi Yao is the recipient of the 6th Oshima Award!!


  • Biogeochemical nitrogen properties of forest soils in the Japanese archipelago

    Rieko Urakawa, Nobuhito Ohte, Hideaki Shibata, Ryunosuke Tateno, Takuo Hishi, Keitaro Fukushima, Yoshiyuki Inagaki, Keizo Hirai, Tomoki Oda, Nobuhiro Oyanagi, Makoto Nakata, Hiroto Toda, Tanaka Kenta, Karibu Fukuzawa, Tsunehiro Watanabe, Naoko Tokuchi, Tatsuro Nakaji, Nobuko Saigusa, Yukio Yamao, Asami Nakanishi, Tsutomu Enoki, Shin Ugawa, Atsushi Hayakawa, Ayumi Kotani, Megumi Kuroiwa, Kazuo Isobe

    Ecological Research vol.30, No. 1 pp. 1–2

    Keywords: Gross nitrogen transformation rate; Litter layer stock; Net nitrogen transformation rate; Nitrification; Nitrogen cycle; Nitrogen mineralization; The Japanese archipelago; Total carbon and nitrogen concentrations; Water-soluble ions; Water-soluble organic carbon

    Abstract This data paper provides some biogeochemical nitrogen (N) properties and related chemical properties of forest soils from 39 sites throughout the Japanese archipelago. The data set was collected and analyzed under the GRENE (Green Network of Excellence) environmental information project and the ReSIN (Regional and comparative Soil Incubation study on Nitrogen dynamics in forest ecosystems) project. The sites cover 44°20”N to 26°50’N and the climate ranges from cool-temperate zone to subtropical zone. At each site, litter on forest floor and soil samples (three or four layers to 50 cm depth) were collected between August and November in 2010–2013 from five soil profiles. From the litter layer samples, the stocks and concentrations of total carbon (C) and N were measured. From the mineral soil samples, bulk density, pH (H2O), total C and N concentrations, net and gross rates of N mineralization, nitrification and concentrations of water-soluble substances were measured. The measurements are relevant for other biogeochemical N studies in forest ecosystems and the data set provides basic information on the N pool and fluxes with related chemical properties of forest soils across the Japanese archipelago. The average rates of net and gross N transformation at 20 °C across the sites were 0.26 ± 0.47 mgN kg-1 soil d-1 for net N mineralization, 0.25 ± 0.45 mgN kg-1 soil d-1 for net nitrification, 4.06 ± 0.47 mgN kg-1 soil d-1 for gross N mineralization, and 1.03 ± 1.29 mgN kg-1 soil d-1 for gross nitrification (average ± SD).

  • Antifungal activity of a termite queen pheromone against egg-mimicking termite ball fungi

    Kenji Matsuura, Takeshi Matsunaga

    Ecological Research vol.30, No. 1 pp. 93–100

    Keywords: Queen pheromone; Termite ball; Semiochemical parsimony; Insect-fungal interaction; Antimicrobial compounds

    Abstract The sophisticated colony organization of eusocial insects is attributed to their elaborate chemical communication systems. Pheromones mediate most behaviors involved in colony organization including foraging, defense, brood care, and caste regulation. The number of candidate compounds available to regulate multiple systems may be biosynthetically finite and the production of several compounds instead of a single one may be more costly. Therefore, strong selection pressures encourage the use of single natural products for many purposes. Such versatility of signal substances is especially characteristic of queen pheromones in eusocial Hymenoptera. However, little is known about the multifunctionality of the recently identified termite queen pheromone. Here, we demonstrate that volatile compounds in the queen pheromone of a termite, Reticulitermes speratus (Kolbe), have fungistatic properties. Application of the pheromone compounds n-butyl-n-butyrate and 2-methyl-1-butanol significantly reduced the germination rates of the egg-mimicking parasitic termite ball fungus. These pheromone compounds also suppressed mycelial growth of the termite ball fungus and some entomopathogenic fungi. However, the inhibitory activity of each substance differed among fungal strains. Termites likely employ these antimicrobial volatiles to protect eggs and queens, and secondarily as communication agents informing queen fertility. This study supports the notion of evolutionary parsimony, wherein pheromones are originally used as defensive compounds and their communicative function develops secondarily, which is well-documented in social Hymenoptera.

  • Relationships among plant genetics, phytochemistry and herbivory patterns in Quercus castanea across a fragmented landscape

    Yurixhi Maldonado-Lopez, Pablo Cuevas-Reyes, Antonio Gonzalez-Rodriguez , Griselda Perez-Lopez, Carlos Acosta-Gomez, Ken Oyama

    Ecological Research vol.30, No. 1 pp. 133–143

    Keywords: Folivores; Leaf miners; Mexico; Microsatellites; Oak

    Abstract Herbivorous insects respond to the chemical variation of their host plants which, in turn, usually has a genetic component. Therefore, it is expected that individual host plants with similar genotypes will have similar secondary chemistries and herbivore communities. However, natural or anthropogenic environmental variation can also influence secondary chemistry and herbivore abundance and composition. Here, we determined the relationships among plant genetics, phytochemistry, and herbivory levels by leaf chewers and miners in the red oak Quercus castanea, across a fragmented landscape. Ten oak individuals were sampled at each of four sites in the Cuitzeo basin, central Mexico. Two sites were small and fragmented forest patches and two were large and continuous patches. Individuals were genotyped with six nuclear microsatellites, and analyzed chemically to determine foliar concentrations of water, total nonstructural carbohydrates, and secondary compounds. Damage by leaf chewers was higher in the small fragments than in the large fragments. Mantel tests indicated significant correlations of the genetic distance among individuals with their chemical similitude, and also of chemical similitude with damage levels by leaf miners, but not with damage by folivores. There was no direct relationship between genetic distance and herbivory levels by any of the two insect guilds. Our results suggest that variation in concentration of secondary metabolites in Q. castanea has a genetic component and that plant chemistry acts as an intermediate link between plant genes and the community of associated herbivores. However, this effect was only apparent for herbivory by leaf miners, probably because these insects interact more intimately with the host, while free-living leaf chewers may be more responsive to environmental variation.

  • Capitulum and rosette leaf avoidance from grazing by large herbivores in Taraxacum

    Noboru Fujita, Ryosuke Koda

    Ecological Research vol.29, No. 4 pp. 529–534

    Keywords: Scape; Livestock; Pasture; Rural habitat; Urban habitat

    Abstract Plants defense against herbivore damage is achieved through resistance and tolerance, of which resistance is composed of avoidance and antibiosis. Plants have developed various adaptations that facilitate escape from herbivory. We hypothesized that post-anthesis prostrate scapes in Taraxacum is an adaptation for avoidance of capitulum grazing by large herbivores. To test this hypothesis, we divided flowering into the following four stages based on the external appearance of the capitulum: green bud, yellow corolla, brown corolla, and white pappus stages. We conducted an experiment in natural pasture in Mongolia to artificially raise capitula and rosette leaves of T. collinum. We measured the natural height of capitula and rosette leaves of the Mongolian pasture and urban species, T. collinum and T. ceratophorum, respectively, and of the Japanese rural and exotic urban species, T. japonicum and T. officinale, respectively. We investigated natural grazing by livestock in the field of the capitula and rosette leaves of the two Mongolian species. In Mongolia, naturally short capitula at the green bud and brown corolla stages and rosette leaves of T. collinum were not grazed. However, artificially raised capitula and rosette leaves of T. collinum and the naturally high capitula and leaves of T. ceratophorum were grazed. Short capitulum and leaf height was shown to be effective for avoidance of livestock grazing in Mongolia. In Japan, T. japonicum and T. officinale showed similar scape behavior to T. collinum and T. ceratophorum, respectively. We discuss the reasons for the capitulum behavior differences in Japan.

  • Variation in microbial function through soil depth profiles in the Kushiro Wetland, northeastern Hokkaido, Japan

    Yukiko Senga, Mikiya Hiroki, Shigeharu Terui, Seiichi Nohara

    Ecological Research vol.30, No. 4 pp. 563–572

    Keywords: Soil microbial function; Decomposition; Phosphate production; Denitrification; Wetland

    Abstract To provide new insights into microbial functions in the Kushiro Wetland, Japan, we measured vertical profiles of fluorescein diacetate hydrolysis (total microbial activity), β-glucosidase and xylosidase (organic matter decomposition), acid phosphatase (phosphate production) and potential denitrifying (denitrification) activities as microbial enzyme activities in soil to depths of approximately 1.5 m from two sites with different vegetation in November 2008 (winter) and August 2009 (summer). Active organic matter decomposition, phosphate production and denitrification were evident in shallow litter and peat layers, and total microbial activity was high. Almost no differences in decomposition and total microbial activity were observed between seasons, whereas phosphate production and denitrification were higher in summer. All activities were low in mid-depth volcanic-ash and clay layers because of low carbon, nitrogen and phosphorus levels. Surprisingly, the total microbial activity and decomposition in deep clay & peat and peat layers were the same as or higher than in shallow layers. However, denitrification was limited, probably because dissolved organic matter containing humic-like substances was unsuitable as a substrate. Moreover, total soil phosphorus levels, acid phosphatase activity and multiple linear regression analysis revealed that the soil in the Kushiro Wetland is likely P limited.