Dear Members of the Zoological Society of Japan
At the Board of Directors meeting of the Zoological Society of Japan held on Friday, June 12, 2026, starting at 1:00 PM, the Editorial Board of Zoological Science nominated candidate papers for the 2026 Zoological Science Award.
As a result of deliberation, the Editorial Board of the Zoological Society of Japan decided to present the 2026 Zoological Science Award to the following seven papers.
The authors of the paper will be presented with a certificate of merit and a cash prize of 50,000 yen.
Yawning and Its Temperature-Dependent Modulation in Leopard Geckos Koki T. Kotake, Sho T. Yamaguchi, Yasutaka Mukai, Zhiwen Zhou, Hiroaki Norimoto Zoological Science 42 (1): 25-30.
https://bioone.org/journals/zoological-science/volume-42/issue-1/zs230123/Yawning-and-Its-Temperature-Dependent-Modulation-in-Leopard-Geckos/10.2108/zs230123.short
Physiology
In this paper, the previously unknown yawning behavior and its function in ectotherms were investigated through detailed behavioral analysis using leopard geckos. By observing them over three days under different temperature conditions, it was revealed that the frequency and duration of yawning change in a temperature-dependent manner, and that it also has a 24-hour periodicity where the yawning frequency increases during the transition from the light phase to the dark phase. At temperature conditions of 30°C or higher, the activity level after yawning behavior significantly increased. These results share high commonality with research findings in endotherms, suggesting that yawning behavior and its function are conserved across vertebrates. Regarding the physiological function of the phenomenon known as yawning, it is expected to provide important insights from an evolutionary perspective and was highly evaluated.
Loss of Photoperiodic Control of Juvenile-Hormone Signaling Pathway Underlying the Evolution of Obligate Parthenogenesis in the Pea Aphid Asano Ishikawa, Hiroki Gotoh, Kota Ogawa, Takashi Kanbe, Shin-ichi Akimoto, Toru Miura Zoological Science 42 (2): 186-195.
https://bioone.org/journals/zoological-science/volume-42/issue-2/zs240075/Loss-of-Photoperiodic-Control-of-Juvenile-Hormone-Signaling-Pathway-Underlying/10.2108/zs240075.full
Physiology
This paper is a study that elucidates the endocrinological basis of the evolutionary transition from "cyclical parthenogenesis" to "obligate parthenogenesis" in the pea aphid, Acyrthosiphon pisum. By comparing strains that form sexual generations in response to photoperiod with strains that have lost photoperiodic response and become obligate parthenogens, the results showed that while juvenile hormone (JH) synthesis- and degradation-related genes exhibit a clear photoperiodic response in the sexual generation-forming strains, this responsiveness is lost in the obligate parthenogenetic strains. In particular, the loss of response in CYP15A, which is involved in the final step of JH synthesis, and JHEH, which is involved in JH degradation, is thought to be directly linked to the loss of the seasonally dependent reproductive mode transition. This study is significant in that it explains the evolutionary loss of phenotypic plasticity at the molecular level as a change in the environmental sensitivity of hormonal signaling pathways, and it has been highly praised as an outstanding study linking evolutionary developmental biology, physiology, and the evolution of environmental response.
Cross-Modal Object Recognition and Reliability Between Visual and Tactile Senses in Octopus (Callistoctopus aspilosomatis) Sumire Kawashima, Yuzuru Ikeda Zoological Science 42 (3): 260-269.
https://bioone.org/journals/zoological-science/volume-42/issue-3/zs240069/Cross-Modal-Object-Recognition-and-Reliability-Between-Visual-and-Tactile/10.2108/zs240069.short
Field: Behavioral Biology
This paper reports on training octopuses to learn objects through either vision or touch, and demonstrates the existence of cross-modal recognition by investigating how these different sensory information are integrated to recognize objects. The researchers established an experimental system capable of separately presenting visual and tactile information of objects, and showed that tactile information is preferentially used over visual information for recognizing novel objects, and that objects learned solely through touch can be identified using visual information alone. These findings not only provide important insights into the sensory integration abilities of octopuses, but also represent significant and highly praised achievements for understanding animal object recognition and representation, as well as their diversity.
Growth, Feeding, and Age of the Inshore Hagfish, Eptatretus burgeri Yoko Yamaguchi Zoological Science 42 (3): 299-308. https://bioone.org/journals/zoological-science/volume-42/issue-3/zs240097/Growth-Feeding-and-Age-of-the-Inshore-Hagfish-Eptatretus-burgeri/10.2108/zs240097.full
Field: Ecology
Hagfishes are major marine scavengers widely distributed in oceans around the world, but their life history has long remained a mystery because they lack the hard tissues necessary for age determination. In this paper, we conducted long-term rearing monitoring of Japanese species for nearly a year and a half, and successfully estimated the growth curve of this species for the first time in the world from the obtained data. As a result, it was suggested that the growth efficiency of this species is extremely low and its lifespan may exceed 50 years. In addition, we clarified the unique ecology that it takes a median of 9 days from feeding to excretion. The results of this study are significant from the perspective of marine biological resource management and ecosystem conservation, and have been highly evaluated.
Successful Maintenance of Chemosynthetic Symbiotic Bacterial Abundance in Hydrothermal Mussels During Long-Term Rearing Experiments Exceeding 1000 days Tetsuro Ikuta, Makoto Sugimura, Ayu Yuasa, Yuta Amari Zoological Science 42 (6): 521-531.
https://bioone.org/journals/zoological-science/volume-42/issue-6/zs250041/Successful-Maintenance-of-Chemosynthetic-Symbiotic-Bacterial-Abundance-in-Hydrothermal-Mussels/10.2108/zs250041.full
Field: Diversity and Evolution
This paper is an ambitious study that achieved the long-term rearing of the deep-sea hydrothermal vent mussel Bathymodiolus septemdierum for over 1,000 days while maintaining its endosymbionts. In addition to supplying Na2S, the authors constructed a rearing system with controlled dissolved oxygen and CO2 concentrations, demonstrating that endosymbionts can be maintained for a long period under hypoxic and high-CO2 conditions. Establishing a long-term rearing system has been a major technical challenge in the study of deep-sea chemosynthetic symbiosis, and this study provides an important foundation for experimentally analyzing the interactions between deep-sea organisms and chemosynthetic endosymbionts. It is highly evaluated for its expected major contribution to future deep-sea biology and symbiotic evolution research.
Lineage-Specific Gene Expansion and Atypical Expression Pattern of Feminizing Gene transformer in Stag Beetles Itsuki Ohtsu, Hayato Kondo, Yasuhiko Chikami, Hideo Dohra, Hiroki Gotoh Zoological Science 42 (6): 571-580.
https://bioone.org/journals/zoological-science/volume-42/issue-6/zs250011/Lineage-Specific-Gene-Expansion-and-Atypical-Expression-Pattern-of-Feminizing/10.2108/zs250011.short
Field of Molecular Biology
This study revealed that lineage-specific gene duplication of the transformer (*tra*) gene—a feminizing gene that plays a central role in insect sex determination—has occurred in the stag beetle family (Lucanidae). Furthermore, the researchers discovered that *tra*, which was traditionally thought to function exclusively in females, is also functionally expressed in males of certain species, demonstrating a phenomenon that cannot be explained by conventional insect sex determination models. These findings suggest the evolution of an unknown sex determination mechanism in stag beetles, and the study has been highly acclaimed as important work that provides new perspectives on the evolutionary diversity and flexibility of sex determination mechanisms in insects.
Intraspecific Variation in Responsiveness to Juvenile Hormone May Underlie Differences in Diapause Strategy Among Daphnia cf. pulex Clones Natsumi Maruoka, Hitoshi Miyakawa Zoological Science 42 (6): 587-595.
https://bioone.org/journals/zoological-science/volume-42/issue-6/zs250019/Intraspecific-Variation-in-Responsiveness-to-Juvenile-Hormone-May-Underlie-Differences/10.2108/zs250019.full
Physiology
Daphnia contribute to population persistence by producing resting eggs when environmental conditions deteriorate. In this paper, we aimed to clarify the endocrine response mechanisms that generate differences in diapause strategies by comparing the reactivity to juvenile hormone (JH) between two genotypes of Daphnia cf. pulex (JPN1 and JPN2) that coexist in the same lake and differ in the frequency of resting egg production. In JPN2, JH exposure significantly increased resting egg production without producing males for sexual reproduction, whereas in JPN1, resting egg production was minimal and male production was induced. Furthermore, the sensitive period for resting egg production was found to be approximately two instars prior to the egg-carrying period, suggesting it occurs earlier than the sensitive period for male production. These results demonstrate for the first time that the difference in resting frequency between the two genotypes is partially explained by differences in reactivity to endogenous JH, which influences population coexistence and dynamics. This paper successfully linked the diversity of life-history strategies with their molecular basis and was highly evaluated.
That's all.
Public Interest Incorporated Foundation, Zoological Society of Japan
