Longer durability of host–parasite interaction increases host density
Patch Thongthaisong, Minoru Kasada, Hans-Peter Grossart, Sabine Wollrab
Oikos, Wiley, 2025年04月
研究論文（学術雑誌）, Comparing cases of parasitism and predation that lead to victim death, parasites need more time to complete victim exploitation. This longer ‘interaction durability' delays energy transfer from host to parasite. During exploitation, parasite virulence differentiates the infected from the susceptible host dynamics. However, how this parasite characteristic influences the dynamics of their host and nonhost (insusceptible) species in the same community is largely unknown. Here, we use mathematical modelling to investigate the influence, exemplifying an experimental plankton community. In this community, nonhost zooplankton feeds on edible nonhost phytoplankton (resource competitor of the host) and parasite propagules released from infected inedible phytoplankton (‘mycoloop' pathway). To assess the effects of parasite–host durability, we contrast parasite–host implementations as Lotka–Volterra predator–prey interaction (immediate energy transfer) with susceptible‐infected (SI) host–parasite interactions. For the latter, parasite energy intake depends on infected host density but not susceptible hosts directly (delayed transfer). We further consider the difference between susceptible and infected host dynamics modulated by parasite virulence via its effect on host nutrient uptake. To assess the within‐community effects, subcommunities are also investigated, excluding/including the parasite without/with the mycoloop. Our results show that, besides host elimination, longer interaction durability of the host–parasite interaction delays parasite attacks on susceptible hosts, allowing them to increase further (a hydra effect), independent of parasite virulence level. This effect observed in the isolated host–parasite systems is preserved in larger communities with negative consequences for the nonhost species, independent of the mycoloop. These theoretical results are supported by empirical observations within and beyond plankton realms. Our study reveals distinctive influences of parasites on community shot‐term dynamics, which stem from the longer interaction durability.

Flexibility in Aquatic Food Web Interactions: Linking Scales and Approaches
Ellen van Velzen, Sabine Wollrab, Onur Kerimoglu, Ursula Gaedke, Hans-Peter Grossart, Minoru Kasada, Helena C. L. Klip, Stefanie Moorthi, Tom Shatwell, Patch Thongthaisong, A. E. Friederike Prowe
Ecosystems, 28, 2, Springer Science and Business Media LLC, 2025年03月24日
研究論文（学術雑誌）, Abstract

Trophic interactions determine food web structure and influence biodiversity, community structure, ecosystem functioning, and food web responses to global change. These interactions are highly flexible, changing on temporal scales from diurnal to evolutionary times due to phenotypic plasticity, rapid evolution and species sorting. Small-scale experimental and theoretical studies of plankton interactions have demonstrated a high relevance of this flexibility for community dynamics and ecosystem processes in small, simplified communities. However, the extent to which this flexibility affects larger-scale systems, for example, global ocean dynamics and their responses to global change, is still poorly understood. Differences in methodology, focus and terminology between research disciplines limit our ability to project established effects of flexible trophic interactions onto larger spatial and temporal scales. We propose to bridge this gap with a general framework for upscaling knowledge from small-scale research to large-scale models. Building on examples from plankton communities, we use this framework to show how mechanisms demonstrated in small-scale studies can be linked to ecosystem functions relevant at large scales. We argue for incorporating flexibility in large-scale process-based models to improve their realism and predictive power, and discuss challenges and ways forward for achieving this. Finally, we suggest several concrete ways for upscaling small-scale studies to make their findings more relevant for large-scale research, to close existing knowledge gaps and to improve our understanding of how flexible trophic interactions affect dynamics and processes across scales.

Rescue or murder? The effect of prey adaptation to the predator subjected to fisheries
Yangke Shang, Minoru Kasada, Michio Kondoh
Ecology and Evolution, 14, 12, Wiley, 2024年12月04日
研究論文（学術雑誌）, Abstract

The concept of “indirect evolutionary rescue” refers to the evolutionary adaptation of an interacting species that can save a focal species from extinction in an unfavorable environment. Although theories suggest that indirect evolutionary rescue may have essential impacts on catchments in the context of fisheries where artificial selection pressure from fishing can drive evolution, its generality and conditions remain uncertain. In this study, by investigating how prey adaptation affects the persistence of a predator subjected to selective harvest with an eco‐evolutionary predator–prey model, we find that prey adaptation tends to deteriorate (facilitate) predator persistence when predator's evolvability is high (low). In the system where the predator possesses high evolvability, selection by fisheries inhibits a predator's adaptation to prey, allowing the prey to escape predation by adaptation. Prey adaptation will affect predator persistence negatively, leading to evolutionary murder. Conversely, in the system where the predator's evolvability is low, the removal of predator individuals by fisheries relaxes predation pressure on prey, making the prey less defensive. Vulnerable prey affects predator persistence positively, resulting in indirect evolutionary rescue. The context‐dependent response of natural resources to fisheries identified in this study suggests that the eco‐evolutionary interplay should be considered for better natural resource management.

Community Science Initiatives Utilizing Environmental DNA
Michio Kondoh, Minoru Kasada, Takuzo Abe, Akihide Kasai, Akihiro Dazai, Reiji Masuda, Satoquo Seino, Shota Suzuki, Yukari Suzuki-Ohno, Akifumi S. Tanabe
Ecological Research Monographs, 83, 99, Springer Nature Singapore, 2024年06月25日
論文集(書籍)内論文

Monitoring of toxic cyanobacterial blooms in Lalla Takerkoust reservoir by satellite imagery and microcystin transfer to surrounding farms
Richard Mugani, Fatima El Khalloufi, Minoru Kasada, El Mahdi Redouane, Mohammed Haida, Roseline Prisca Aba, Yasser Essadki, Soukaina El Amrani Zerrifi, Sven-Oliver Herter, Abdessamad Hejjaj, Faissal Aziz, Naaila Ouazzani, Joana Azevedo, Alexandre Campos, Anke Putschew, Hans-Peter Grossart, Laila Mandi, Vitor Vasconcelos, Brahim Oudra
Harmful Algae, 135, 102631, 102631, Elsevier BV, 2024年05月
研究論文（学術雑誌）

Critical role of parasite‐mediated energy pathway on community response to nutrient enrichment
Patch Thongthaisong, Minoru Kasada, Hans‐Peter Grossart, Sabine Wollrab
Ecology and Evolution, 12, 12, Wiley, 2022年12月13日
研究論文（学術雑誌）, Abstract

Parasites form an integral part of food webs, however, they are often ignored in classic food web theory or limited to the investigation of trophic transmission pathways. Specifically, direct consumption of parasites by nonhost predators is rarely considered, while it can contribute substantially to energy flow in food webs. In aquatic systems, chytrids constitute a major group of fungal parasites whose free‐living infective stages (zoospores) form a highly nutritional food source to zooplankton. Thereby, the consumption of zoospores can create an energy pathway from otherwise inedible phytoplankton to zooplankton (“mycoloop”). This parasite‐mediated energy pathway might be of special importance during phytoplankton blooms dominated by inedible or toxic primary producers like cyanobacteria, which are on the rise with eutrophication and global warming. We theoretically investigated community dynamics and energy transfer in a food web consisting of an edible nonhost and an inedible host phytoplankton species, a parasitic fungus, and a zooplankton species grazing on edible phytoplankton and fungi. Food web dynamics were investigated along a nutrient gradient contrasting nonadaptive zooplankton species representative for filter feeders like cladocerans and zooplankton with the ability to actively adapt their feeding preferences like many copepod species. Overall, the importance of the mycoloop for zooplankton increases with nutrient availability. This increase is smooth for nonadaptive consumers. For adaptive consumers, we observe an abrupt shift from an almost exclusive preference for edible phytoplankton at low nutrient levels to a strong preference for parasitic fungi at high nutrient levels. The model predicts that parasitic fungi could contribute up to 50% of the zooplankton diet in nutrient‐rich environments, which agrees with empirical observations on zooplankton gut content from eutrophic systems during blooms of inedible diatoms or cyanobacteria. Our findings highlight the role of parasite‐mediated energy pathways for predictions of energy flow and community composition under current and future environmental change.

Evolution of competitive traits changes species diversity in a natural field
Yuya Fukano, Yuuya Tachiki, Minoru Kasada, Kei Uchida
Proceedings of the Royal Society B: Biological Sciences, 289, 1983, The Royal Society, 2022年09月28日
研究論文（学術雑誌）, Studying the interaction between evolutionary and ecological processes (i.e. eco-evolutionary dynamics) has great potential to improve our understanding of biological processes such as species interactions, community assembly and ecosystem functions. However, most experimental studies have been conducted under controlled laboratory or mesocosm conditions, and the importance of these interactions in natural field communities has not been evaluated. In this study, we focused on the contemporary divergence of a competitive trait (the height–width ratio) of an annual grass Eleusine indica between urban and farmland populations and investigated how trait evolution affects ecological processes by transplanting E. indica individuals from lineages with different trait values into semi-natural grassland. The competitive trait of the transplanted individuals not only affected their own growth and fitness, but also affected the vegetative growth of the competing species and the species diversity. These results indicate that the evolution of competitive traits, even in a single species, can influence the community species diversity through changes in interspecific interactions. Eco-evolutionary interactions therefore play a crucial role in natural field environments. Our results suggest that understanding intraspecific variation in competitive traits driven by rapid evolution is essential for understanding interspecific competitive interactions, community assembly and species diversity.

Ecosystem-based disaster risk reduction can benefit biodiversity conservation in a Japanese agricultural landscape
Minoru Kasada, Kei Uchida, Naoto Shinohara, Takehito Yoshida
Frontiers in Ecology and Evolution, 10, Frontiers Media SA, 2022年09月07日, ［筆頭著者］
研究論文（学術雑誌）, Ecosystem-based disaster risk reduction (Eco-DRR) has attracted increased attention as a sustainable way to achieve both disaster risk reduction and biodiversity conservation, although there have been few quantitative evaluations of the potential impacts of Eco-DRR on biodiversity. Here, we examined the influences of flood hazard and land-use patterns on biodiversity by focusing on the species richness of plants, butterflies and odonates, and the abundance of two frog species in a rural landscape of Wakasa town, Fukui Prefecture, Japan. The direct effect of exposure to flood hazard on the studied taxa was not significant, whereas landscape factors associated with flood hazard significantly influenced either of the taxa in different magnitudes. We then exercised a scenario analysis by replacing urban land-use by non-urban, agricultural land-use (paddy fields in this case) to reduce exposure to flood hazard and projected the impacts on biodiversity. Our results demonstrated that the land-use replacement potentially reduces the risk of flooding by up to 5.19 billion yen (ca. 46 million US$) and, at the same time, positively influences the species richness and abundance, although the ecological impacts are different depending on taxon and spatial location. The land-use replacement was expected to result in the increase of plant richness and abundance of Daruma pond frog at a location by up to 16 and 25%, respectively. On the other hand, butterfly richness at a location was presumed to decrease by until −68%, probably due to their dependence on domestic gardens. The abundance of Japanese wrinkled frog did not show such a clear spatial variation. This study highlights the significance of land-use replacement as an Eco-DRR measure to reduce the disaster risk and conserve biodiversity in the agricultural landscape.

Differing Escape Responses of the Marine Bacterium Marinobacter adhaerens in the Presence of Planktonic vs. Surface-Associated Protist Grazers
Luis Alberto Villalba, Minoru Kasada, Luca Zoccarato, Sabine Wollrab, Hans Peter Grossart
International Journal of Molecular Sciences, 23, 17, 10082, 10082, MDPI AG, 2022年09月03日
研究論文（学術雑誌）, Protist grazing pressure plays a major role in controlling aquatic bacterial populations, affecting energy flow through the microbial loop and biogeochemical cycles. Predator-escape mechanisms might play a crucial role in energy flow through the microbial loop, but are yet understudied. For example, some bacteria can use planktonic as well as surface-associated habitats, providing a potential escape mechanism to habitat-specific grazers. We investigated the escape response of the marine bacterium Marinobacter adhaerens in the presence of either planktonic (nanoflagellate: Cafeteria roenbergensis) or surface-associated (amoeba: Vannella anglica) protist predators, following population dynamics over time. In the presence of V. anglica, M. adhaerens cell density increased in the water, but decreased on solid surfaces, indicating an escape response towards the planktonic habitat. In contrast, the planktonic predator C. roenbergensis induced bacterial escape to the surface habitat. While C. roenbergensis cell numbers dropped substantially after a sharp initial increase, V. anglica exhibited a slow, but constant growth throughout the entire experiment. In the presence of C. roenbergensis, M. adhaerens rapidly formed cell clumps in the water habitat, which likely prevented consumption of the planktonic M. adhaerens by the flagellate, resulting in a strong decline in the predator population. Our results indicate an active escape of M. adhaerens via phenotypic plasticity (i.e., behavioral and morphological changes) against predator ingestion. This study highlights the potentially important role of behavioral escape mechanisms for community composition and energy flow in pelagic environments, especially with globally rising particle loads in aquatic systems through human activities and extreme weather events.

State‐space model combining local camera data and regional administration data reveals population dynamics of wild boar
Minoru Kasada, Yoshihiro Nakashima, Keita Fukasawa, Gota Yajima, Hiroyuki Yokomizo, Tadashi Miyashita
Population Ecology, 65, 1, 80, 92, 2022年08月31日, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

Bacterioplankton Associated with Toxic Cyanobacteria Promote Pisum sativum (Pea) Growth and Nutritional Value through Positive Interactions
Richard Mugani, Fatima El Khalloufi, El Mahdi Redouane, Mohammed Haida, Soukaina El Amrani Zerrifi, Alexandre Campos, Minoru Kasada, Jason Woodhouse, Hans-Peter Grossart, Vitor Vasconcelos, Brahim Oudra
Microorganisms, 10, 8, 1511, 1511, MDPI AG, 2022年07月26日
研究論文（学術雑誌）, Research on Plant Growth-Promoting Bacteria (PGPB) has focused much more on rhizospheric bacteria. However, PGPB associated with toxic cyanobacterial bloom (TCB) could enter the rhizosphere through irrigation water, helping plants such as Pisum sativum L. (pea) overcome oxidative stress induced by microcystin (MC) and improve plant growth and nutritional value. This study aimed to isolate bacteria associated with toxic cyanobacteria, test PGPB properties, and inoculate them as a consortium to pea seedlings irrigated with MC to investigate their role in plant protection as well as in improving growth and nutritional value. Two bacterioplankton isolates and one rhizosphere isolate were isolated and purified on a mineral salt medium supplemented with 1000 μg/L MC and identified via their 16S rRNA gene. The mixed strains were inoculated to pea seedlings in pots irrigated with 0, 50, and 100 μg/L MC. We measured the morphological and physiological parameters of pea plants at maturity and evaluated the efficiency of the plant’s enzymatic and non-enzymatic antioxidant responses to assess the role and contribution of PGPB. Both bacterioplankton isolates were identified as Starkeya sp., and the rhizobacterium was identified as Brevundimonas aurantiaca. MC addition significantly (p < 0.05) reduced all the growth parameters of the pea, i.e., total chlorophyll content, leaf quantum yield, stomatal conductance, carotenoids, and polyphenol contents, in an MC concentration-dependent manner, while bacterial presence positively affected all the measured parameters. In the MC treatment, the levels of the pea’s antioxidant traits, including SOD, CAT, POD, PPO, GST, and ascorbic acid, were increased in the sterile pots. In contrast, these levels were reduced with double and triple PGPB addition. Additionally, nutritional values such as sugars, proteins, and minerals (Ca and K) in pea fruits were reduced under MC exposure but increased with PGPB addition. Overall, in the presence of MC, PGPB seem to positively interact with pea plants and thus may constitute a natural alternative for soil fertilization when irrigated with cyanotoxin-contaminated water, increasing the yield and nutritional value of crops.

From microbes to mammals: Pond biodiversity homogenization across different land‐use types in an agricultural landscape
D. Ionescu, M. Bizic, R. Karnatak, C. L. Musseau, G. Onandia, M. Kasada, S. A. Berger, J. C. Nejstgaard, M. Ryo, G. Lischeid, M. O. Gessner, S. Wollrab, H.‐P. Grossart
Ecological Monographs, 92, 3, Wiley, 2022年05月31日
研究論文（学術雑誌）

Positive and negative effects of land abandonment on butterfly communities revealed by a hierarchical sampling design across climatic regions
Naoki Sugimoto, Keita Fukasawa, Akio Asahara, Minoru Kasada, Misako Matsuba, Tadashi Miyashita
Proceedings of the Royal Society B: Biological Sciences, 289, 1971, The Royal Society, 2022年03月23日
研究論文（学術雑誌）, Land abandonment may decrease biodiversity but also provides an opportunity for rewilding. It is therefore necessary to identify areas that may benefit from traditional land management practices and those that may benefit from a lack of human intervention. In this study, we conducted comparative field surveys of butterfly occurrence in abandoned and inhabited settlements in 18 regions of diverse climatic zones in Japan to test the hypotheses that species-specific responses to land abandonment correlate with climatic niches and habitat preferences. Hierarchical models that unified species occurrence and habitat preferences revealed that negative responses to land abandonment were associated with species that have cold climatic niches and use open habitats, suggesting that species negatively impacted by land abandonment will decline more due to future climate warming. Maps representing species gains and losses due to land abandonment, which were created from the model estimates, showed similar geographical patterns, but some areas exhibited high species losses relative to gains. Our hierarchical modelling approach was useful for scaling up local-scale effects of land abandonment to a macro-scale assessment, which is crucial to developing spatial conservation strategies in the era of depopulation.

Idea paper: Controlling trait adaptation to decrease population densities for conservation and management
Minoru Kasada, Masato Yamamichi
Ecological Research, 37, 4, 475, 480, Wiley, 2022年02月27日, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

Effectiveness of signs of activity as relative abundance indices for wild boar
Daishi Higashide, Takeo Kuriyama, Shun Takagi, Yoshihiro Nakashima, Keita Fukasawa, Gota Yajima, Minoru Kasada, Mayumi Yokoyama
Wildlife Biology, 2021, 4, Wiley, 2021年10月15日
研究論文（学術雑誌）

The timescale of environmental fluctuations determines the competitive advantages of phenotypic plasticity and rapid evolution
Minoru Kasada, Takehito Yoshida
Population Ecology, 62, 4, 385, 394, Wiley, 2020年07月21日, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

Human interest meets biodiversity hotspots: A new systematic approach for urban ecosystem conservation
Minoru Kasada, Misako Matsuba, Tadashi Miyashita
PLOS ONE, 12, 2, e0172670, e0172670, Public Library of Science (PLoS), 2017年02月24日, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

Experimental evidence that high humidity is an essential cue for web building in Pasilobus spiders
Tadashi Miyashita, Minoru Kasada, Akio Tanikawa
Behaviour, 154, 7-8, 709, 718, Brill, 2017年
研究論文（学術雑誌）, Spiders in the subfamily Cyrtarachninae, including bolas spiders, are moth specialists, and it has been suggested that these spiders initiate web-weaving under high humidity. Here we used Pasilobus hupingensis to experimentally test whether Cyrtarachninae spiders build webs exclusively under high humidity. The results showed that humidity, as well as temperature and prey feeding history, affected web-building probability, but humidity had a much stronger effect. Moreover, spiders never constructed webs at under <70% humidity. We suggest that a mechanical property in sticky materials derived from moth specialization; namely, unusually high, yet rapidly degrading stickiness, is likely to have promoted the evolution of plastic foraging behaviour that varies with humidity.

Form of an evolutionary tradeoff affects eco-evolutionary dynamics in a predator–prey system
Minoru Kasada, Masato Yamamichi, Takehito Yoshida
Proceedings of the National Academy of Sciences, 111, 45, 16035, 16040, 2014年10月21日, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

階層性のあるゲーム理論の研究
笠田 実, 阿部 真人, 池上 高志
シミュレーション＆ゲーミング, 2011年06月25日, ［筆頭著者, 責任著者］
日本語, 研究論文（学術雑誌）

Rで基礎から学ぶ統計学
Schmuller, Joseph(笠田, 実)
東京化学同人, 2023年02月, 9784807920310, xvii, 329p, 日本語, ［単訳］