Shigeto Dobata

Shigeto Dobata
The University of Tokyo | Todai · Department of General Systems Studies

PhD

About

70
Publications
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536
Citations

Publications

Publications (70)
Article
Full-text available
Cooperation is subject to cheating strategies that exploit the benefits of cooperation without paying the fair costs, and it has been a major goal of evolutionary biology to explain the origin and maintenance of cooperation against such cheaters. Here, we report that cheater genotypes indeed coexist in field colonies of a social insect, the parthen...
Article
Full-text available
Cooperation in biological, social, and economic groups is underpinned by public goods that are generated by group members at some personal cost. Theory predicts that public goods will be exploited by cheaters who benefit from the goods by not paying for them, thereby leading to the collapse of cooperation. This situation, described as the "public g...
Article
Full-text available
All organisms with sexual reproduction undergo a process of mating, which essentially involves the encounter of two individuals belonging to different sexes. During mate search, both sexes should mutually optimize their encounters, thus raising a question of how they achieve this. Here, we show that a population with sexually dimorphic movement pat...
Preprint
Full-text available
The evolution of complexity is one of the prime features of life on Earth. Although well accepted as the product of adaptation, the dynamics underlying the evolutionary build-up of complex adaptive systems remains poorly resolved. Using simulated robot swarms that exhibit ant-like group foraging with trail pheromones, we show that their swarm intel...
Article
The ant genus Monomorium is one of the most species-rich but taxonomically problematic groups in the hyperdiverse subfamily Myrmicinae. An East Asian species, M. triviale Wheeler, produces both reproductive queens and sterile workers via obligate thelytokous parthenogenesis. Here, we describe the immature forms of M. triviale based on light and sca...
Article
Reproductive division of labour is a hallmark of eusocial insects. However, its stability can often be hampered by the potential for reproduction by otherwise sterile nest-mates. Dominance hierarchy has a crucial role in some species in regulating which individuals reproduce. Compared with those in vertebrates, the dominance hierarchies in eusocial...
Preprint
The ant genus Monomorium is one of the most species-rich but taxonomically problematic groups in the hyperdiverse subfamily Myrmicinae. An East Asian species, M. triviale Wheeler, W. M., produces both reproductive queens and sterile workers via obligate thelytokous parthenogenesis. Here, we describe the immature forms of M. triviale based on light...
Article
Full-text available
Monomorium is one of the most species-rich yet taxonomically problematic ant genus. An East Asian species, M. triviale Wheeler, W.M., 1906, is reproduced by obligate thelytokous parthenogenesis and performs strict reproductive division of labor. We sequenced the M. triviale mitogenome using next-generation sequencing methods. The circular mitogenom...
Article
Full-text available
We report comprehensive evidence for obligatory thelytokous parthenogenesis in an ant Monomorium triviale . This species is characterized by distinct queen–worker dimorphism with strict reproductive division of labor: queens produce both workers and new queens without mating, whereas workers are completely sterile. We collected 333 nests of this sp...
Preprint
Full-text available
Monomorium is one of the most species-rich yet taxonomically problematic ant genera. An East Asian species, M. triviale Wheeler, W.M., 1906, reproduces by obligate thelytokous parthenogenesis and performs strict reproductive division of labor. We sequenced the M. triviale mitogenome using next-generation sequencing methods. The circular mitogenome...
Preprint
Full-text available
We report comprehensive evidence for obligatory thelytokous parthenogenesis in an ant Monomorium triviale . This species is characterized by distinct queen–worker dimorphism with strict reproductive division of labor: queens produce both workers and new queens without mating, whereas workers are completely sterile. We collected 333 nests of this sp...
Article
Evolutionary ecological theory suggests that selection arising from interactions with conspecifics, such as sexual and kin selection, may result in evolution of intraspecific conflicts and evolutionary ‘tragedy of the commons’. Here, we propose that such an evolution of conspecific conflicts may affect population dynamics in a way that enhances spe...
Article
Self-organizing biological systems, such as colonies of social insects, are characterized by their decentralized control and flexible responses to changing environments, often likened to swarm intelligence. Although decentralized control is well known to be a product of local interactions among agents, without the need for a bird's-eye view, indire...
Article
Eusocial insects are characterized by a well‐developed division of labour among castes. Although the successful division of labour should stem from behavioural differentiation depending on caste identity, caste‐specific intrinsic behavioural characteristics might be masked by social interactions within colonies. The present study explores caste‐spe...
Article
Full-text available
How should females and males move to search for partners whose exact location is unknown? Theory predicts that the answer depends on what they know about where targets can be found, raising the question of how actual animals update their mate search patterns to increase encounter probability when conditions change. Here, we show that termites adapt...
Article
Full-text available
The evolution of complexity is one of the prime features of life on Earth. Although well accepted as the product of adaptation, the dynamics underlying the evolutionary build-up of complex adaptive systems remains poorly resolved. Using simulated robot swarms that exhibit ant-like group foraging with trail pheromones, we show that their self-organi...
Article
Full-text available
The use of conspecific cues as social information in decision making is widespread among animals; but, because this social information is indirect, it is error-prone. During resource acquisition, conspecific cues also indicate the presence of competitors; therefore, decision makers are expected to utilize direct information from resources and modif...
Article
We investigated colony-level foraging activities of Diacamma sp., a queenless ponerine ant, in the field. Our aim was to elucidate the presence of any pattern in foraging activity in field colonies in relation to: (1) circadian rhythm, (2) physical environmental conditions such as extreme temperatures, (3) seasonality, and (4) short-term foraging e...
Preprint
Full-text available
When searching for targets whose location is not known, animals should benefit by adopting movement patterns that promote random encounters. During mate search, theory predicts that the optimal search pattern depends on the expected distance to potential partners. A key question is whether actual males and females update their mate search patterns...
Article
Full-text available
Animals have evolved various sex-specific characteristics to improve the efficiency of mating encounters. One is the sex-specific attracting signal. Signal receivers perform a combination of random search and navigation before and after signal detections. On the other hand, signal senders can also modify their movement patterns to optimize their en...
Preprint
Full-text available
The caste system of termites is an example of phenotypic plasticity. The castes differ not only in morphology and physiology, but also in behavior. As most of their behaviors within colonies involve nestmates, it is difficult to extract innate differences among castes. In this study, we focused on movement patterns of isolated individuals of Hodote...
Article
Full-text available
Invasions are ecologically destructive and can threaten biodiversity. Trophic flexibility has been proposed as a mechanism facilitating invasion, with more flexible species better able to invade. The termite hunting needle ant Brachyponera chinensis was introduced from East Asia to the United States where it disrupts native ecosystems. We show that...
Article
Full-text available
The study of collective decision-making spans various fields such as brain and behavioural sciences, economics, management sciences, and artificial intelligence. Despite these interdisciplinary applications, little is known regarding how a group of simple 'yes/no' units, such as neurons in the brain, can select the best option among multiple option...
Article
Full-text available
Tracking animal movements such as walking is an essential task for understanding how and why animals move in an environment and respond to external stimuli. Different methods that implemented image analysis and a data logger such as GPS have been used in laboratory experiments and in field studies, respectively. Recently, animal movement patterns w...
Article
Full-text available
Tracking animal movements such as walking is an essential task for understanding how and why animals move in an environment and respond to external stimuli. Different methods that implemented image analysis and a data logger such as GPS have been used in laboratory experiments and in field studies, respectively. Recently, animal movement patterns w...
Data
The histograms of the data of mean speed, mean angle and max speed. (PDF)
Data
The distribution of step lengths for all individuals. Combinations of a letter and a number indicates the analyzed axis and the individuals. Black dots are observations, red and blue dashed lines are truncated Pareto and competing exponential distributions, respectively, fitted to the data. (PDF)
Data
Maximum likelihood estimation analysis results for the individuals whose trajectories are determined as TP for either x or y axis. TP is truncated Pareto, Exp is exponential; OOM is order of magnitude. (PDF)
Data
Maximum likelihood estimation analysis results for the individuals whose trajectories are determined as unclassified. TP is truncated Pareto, Exp is exponential; OOM is order of magnitude. (PDF)
Data
The data and trajectories obtained in our experiments. (ZIP)
Data
Maximum likelihood estimation analysis results for the individuals whose trajectories are determined as TP for both x and y axis. TP is truncated Pareto, Exp is exponential; OOM is order of magnitude. (PDF)
Article
The colony structures of social insects vary greatly among species. In ant societies, the number of queens within a colony is variable during colony maturation. We investigated the social structure of a polygynous ant Crematogaster osakensis in a series of field and laboratory experiments. First, the initial colonies headed by multiple queens were...
Article
Full-text available
Field robots are widely used to accomplish a variety of tasks in many different fields. However, setting of the locomotive ability of these robots at the design phase may prevent the traversal of unknown rough terrain. To address this shortcoming of existing robots, we designed a robot that is able to modify its environment by using polyurethane fo...
Article
Full-text available
In swarm robotics, communication among the robots is essential. Inspired by biological swarms using pheromones, we propose the use of chemical compounds to realize group foraging behavior in robot swarms. We designed a fully autonomous robot, and then created a swarm using ethanol as the trail pheromone allowing the robots to communicate with one a...
Conference Paper
Red harvester ants allocate themselves to some tasks. In this paper, we propose the ODE model which represents their macro behaviors. In this model, colony size fluctuates due to workers' birth and death. Using the simulator based on this model, we investigate the relationship between survivability of colony and rate of state transition from search...
Conference Paper
This paper describes an implementation of Lévy walk (or Lévy flight) to pheromone communicating swarm robots. Lévy flight is a special class of random walk in which the step length distribution is given by power law distribution. Lévy flight is known to maximize the efficiency of resource searches in uncertain environments. Using computer simulatio...
Article
Policing against selfishness is now regarded as the main force maintaining cooperation, by reducing costly conflict in complex social systems. Although policing has been studied extensively in social insect colonies, its coevolution against selfishness has not been fully captured by previous theories. In this study, I developed a two-trait quantita...
Conference Paper
Full-text available
The recruiting system in foraging ant colonies is a typical example of swarm intelligence. The system is underpinned by the use of volatile pheromones which form a trail connecting from nest to food. We have incorporated this property into the behavior of the swarm of real robots. Because the trail is narrow, avoiding overcrowding on the trail, as...
Article
Full-text available
Colonies of eusocial Hymenoptera, such as ants, bees and wasps, have long been recognized as candidates for the study of genomic imprinting on the grounds of evolutionary conflicts that arise from close interactions among colony members and relatedness asymmetry owing to haplodiploidy. Although a general kinship theory of genomic imprinting predict...
Article
Full-text available
Sex mosaicism, also called gynandromorphism, refers to an accidental phenomenon in dioecious organisms (mainly animals) in which an individual phenotype includes both female and male characteristics. Despite the rarity of this phenomenon, elucidating the mechanisms of naturally occurring sex mosaicism should deepen our understanding of diverse sex...
Article
We report the presence and effects of parasitoid larvae (Hymenoptera) in the carabid beetle Poecilus versicolor (Sturm). Dissection of one female and one male live host found 33 and 25 hymenopteran larvae, respectively. Although eggs were absent in the female host, likely because of consumption by parasitoids, distinct corpora lutea (present in par...
Article
Full-text available
We review some aspects of the biology of the ant Pristomyrmex punctatus, in which the winged queen caste is absent and wingless females reproduce by thelytokous parthenogenesis. The majority of females have two ovarioles, whereas up to 50% of colonies contain large-bodied females which have four ovarioles. We call the former workers and the latter...
Article
How cooperation can arise and persist, given the threat of cheating phenotypes, is a central problem in evolutionary biology, but the actual significance of cheating in natural populations is still poorly understood. Theories of social evolution predict that cheater lineages are evolutionarily short-lived. However, an exception comes from obligate...
Conference Paper
Full-text available
Social organisms form a swarm and forage preys, collectively and effectively [1]. The swarm has to inhibit a variance of foraging frequency for survival, which ensures stable and predictable income. In the previous study, we focused on ”trail pheromone” system which enables robots to communicate one another [2]. In the present study, we analysed st...
Article
This article documents the addition of 283 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Agalinis acuta; Ambrosia artemisiifolia; Berula erecta; Casuarius casuarius; Cercospora zeae-maydis; Chorthippus parallelus; Conyza canadensis; Cotesia sesamiae; Epinephelus acanthistius;...
Article
Full-text available
Biological cooperation is vulnerable to cheaters that exploit the benefits of cooperation without contributing to these benefits, thus the control of cheating is important to maintain cooperative systems. Recently, we reported a cheater lineage in a field population of the Japanese ant Pristomyrmex punctatus. This species is characterized by its as...
Conference Paper
Full-text available
In this paper, we discuss the concentration dependency of pheromone communication in swarm robotics. Instead of a pheromone trail and the insect antenna, we used ethanol and an alcohol sensor. This experimental system has a trade-off problem; high concentrations of the pheromone yield high signal strength but the signal duration is short, while low...
Article
Full-text available
Mnais costalis and M. pruinosa are damselflies (Odonata: Calopterygidae) with low dispersal abilities, both during their aquatic stream-living immature stage and their flying adult stage. A previous nuclear DNA (nDNA) sequencing and morphology study showed that these two species are very closely related, and cohabit widely in western Japan. The two...
Article
Much variation occurs in morphology and colouration among individuals of Japanese Mnais spp. It has been noted that 2 groups of Mnais often cohabit a stream in western Japan. There is, however, no clear morphological difference in ♂ appendages and penis between the 2 groups, and this makes it difficult to determine their taxonomic status. In this s...

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