Biology subjects

Kubo, H.

Publications and source records attributed to Kubo, H..

4 recordsLinked to original sources

bioRxiv2026

Observational satiety: watching yourself eat induces more fullness than watching another

Appetite is shaped not only by physiological need but by the sensory experience of eating and its social context. Can watching food being eaten itself induce satiety, and does it matter who is seen eating? In a functional MRI study (N = 41), participants watched videos of a wanted snack being eaten from their own perspective (self) or, using identical footage shown vertically inverted, as another's (other), holding food identity and visual content constant so that only the attributed agent varied. Observed eating reduced wanting, but not liking, for the eaten foods, whether one's own or another's; crucially, reported fullness increased only when the eating was seen as one's own. In the brain, food-value regions responded to watching eating in both conditions, a shared signal that strengthened over time. Yet only self-attributed eating engaged a self-specific, value-related response in the ventral striatum and medial prefrontal cortex, and orbitofrontal activity during self-eating scaled with each person's reported satiety, whereas watching another eat instead engaged the temporoparietal mentalizing network without a comparable rise in fullness. A large online survey (N = 1,000; ages 15-97) reproduced the behavioral effect across the adult lifespan, and a real-eating experiment reproduced its sensory-specific pattern. Watching eating, and whose eating it is, can thus recalibrate appetite through separate food-value and social-cognitive routes. This "observational satiety" offers a non-invasive route to study food wanting, of potential relevance to social eating and to today's food-media environments.

neuroscience↗

bioRxiv2026

Evolutionary branching of male emergence timing: Trade-offs and variance asymmetry as drivers of dimorphism.

Classical models of protandry predict unimodal male emergence timing, yet empirical observations in butterflies and bees reveal dimorphism: early-emerging small males coexist with late-emerging large males. The evolutionary mechanisms underlying such discrete alternative reproductive strategies in emergence timing remain poorly understood. In this study, we developed a mathematical model using an adaptive dynamics framework to investigate the conditions under which dimorphic male emergence timing evolves. We explored two potential mechanisms: (1) a trade-off between emergence timing and male competitiveness, and (2) differences in the variance of emergence timing between the sexes. Our analysis demonstrates that both mechanisms produce evolutionary branching, and that extreme variance asymmetry between sexes can generate multiple branching events, yielding three or more distinct male clusters. These findings provide a theoretical foundation for understanding the evolution of alternative reproductive strategies in emergence timing, with implications for other systems where reproductive success depends on temporal overlap between the sexes. We provide testable predictions that a positive correlation between emergence timing and male body size or competitiveness should be observed under the trade-off mechanism, and that the variance in emergence timing within each male morph should be smaller than that of females under the variance asymmetry mechanism.

evolutionary biology↗

bioRxiv2024

Male Dimorphism and Emergence Strategies: A Mathematical Model of Protandry in Fabriciana nerippe Felder, 1862

In many butterfly species, males emerge earlier than females as part of a strategy to maximize male reproductive success. Although behavioral ecological studies using mathematical models have been conducted to explain this phenomenon, certain emergence patterns remain unexplained. In the butterfly species Fabriciana nerippe, some males emerge at the same time as females, in addition to males that emerge earlier than the females. However, it is unclear what emergence patterns occur in populations with male dimorphism, as observed in this species. In this study, we showed the existence of male body size dimorphism in Fabriciana nerippe by conducting a comparative analysis of forewing lengths between males and females. In addition, we developed a comprehensive mathematical model to investigate emergence patterns in the presence of dimorphic males. By introducing a trade-off between large size and early emergence, the model considered a scenario where small early-emerging and large late-emerging males could coexist. Numerical analysis demonstrated the emergence patterns of these two male types with a switch in emergence time. Furthermore, the higher the death rate before emergence, the earlier the emergence switch. These findings suggested that the timing of the switch depends on the death rate and is influenced by environmental factors. This work contributes to ecological and theoretical studies on timing dimorphism in life-history strategies across a broader range of species. HighlightsO_LIWe confirmed the existence of male body-size dimorphism corresponding to emergence timing in Fabriciana nerippe. C_LIO_LIWe developed a comprehensive model of male emergence patterns incorporateing male dimorphism. C_LIO_LIWe assumed a trade-off between early emergence and large body size. C_LIO_LIThe timing of male emergence switching is influenced by death rate and reproductive advantage of large males. C_LI

ecology↗

bioRxiv2019

An evolutionarily conserved mechanism for production of secondary meristems in land plants

A variety of plants in diverse taxa can reproduce asexually via vegetative propagation, in which clonal propagules with new meristem(s) are generated directly from vegetative organs. A basal land plant, Marchantia polymorpha, develops clonal propagules, gemmae, in a specialized receptacle, gemma cup. Here we report an R2R3-MYB transcription factor, designated GEMMA CUP-ASSOCIATED MYB 1 (GCAM1), which is an essential regulator of gemma cup development in M. polymorpha. Although gemma cups are a characteristic gametophyte organ for vegetative reproduction in a taxonomically restricted group of liverwort species, phylogenetic and interspecific complementation analyses supported the orthologous relationship of GCAM1 to regulatory factors for axillary meristem formation, e.g. Arabidopsis RAXs and tomato Blind, in angiosperm sporophytes. The present findings in M. polymorpha suggest an ancient acquisition of a regulatory mechanism for production of secondary meristems, and the use of the mechanism for diverse developmental programs during land plant evolution.

plant biology↗