Biology subjects

Nojiri, K.

Publications and source records attributed to Nojiri, K..

5 recordsLinked to original sources

bioRxiv2026

A theoretical framework for aerodynamic braking and landing in gliding mammals

Gliding enables mammals to forage and escape from predators by moving between discontinuous forests. Its benefits depend not only on glide distance but also on the ability to decelerate and land safely. This study developed a theoretical framework linking glide distance, gliding velocity, aerodynamic braking, body mass, and braking distance. Twenty-two representative distance-velocity observations from eight studies and five species were compiled. Among distance-velocity models, log-distance and saturated with V0 models received nearly equivalent support. Both models predicted increasing velocity with glide distance, with the rate of increase declining at longer distances. For a 1 kg animal undergoing a 60% reduction in velocity, predicted kinetic energy remaining immediately before contact increased from 4.80-5.14J at 20 m to 8.13-8.90 J at 80 m. This velocity reduction corresponded to a dissipation of 84% of approach kinetic energy before contact. Over a braking distance of 1 m, the required mean deceleration increased from 2.57-2.75 g at 20 m to 4.35-4.77 g at 80 m. At 80 m, shortening the braking distance from 4 to 0.5 m increased the required deceleration from 1.09-1.19 to 8.70-9.53 g. These results indicate that the absolute energetic and deceleration requirements of landing increase with glide distance, even when velocity is close to an asymptote. These results provide a quantitative basis for considering aerodynamic braking and landing requirements alongside conventional measures of glide performance. Summary statementModels quantify how glide distance, aerodynamic braking, and braking distance affect pre-contact kinetic energy and deceleration requirements in gliding mammals.

evolutionary biology↗

bioRxiv2026

Convergent gliding, divergent ecology: Environmental drivers of gliding vertebrates in Southeast Asia

Gliding has evolved repeatedly across vertebrates and is often regarded as a classic example of convergent evolution associated with arboreal habitats. However, it remains unclear whether convergent locomotion corresponds to shared ecological responses across taxa. In this study, we investigated the distribution patterns and environmental drivers of gliding vertebrates in Southeast Asia using occurrence records and environmental variables representing climate and forest structure. We analyzed five major groups, including flying lemurs, flying squirrels, gliding lizards, gliding snakes, and gliding frogs, using presence-background logistic regression models. Across taxa, temperature seasonality showed consistently negative effects, while canopy height showed positive effects, indicating a shared association with climatically stable environments and well-developed vertical forest structure. In contrast, other environmental variables exhibited substantial taxon-specific variation. For example, elevation showed a strong negative effect only in gliding snakes, suggesting a tendency toward lowland habitats, whereas precipitation variables had limited explanatory power for gliding frogs. These results demonstrate that, despite the convergent evolution of gliding locomotion, ecological responses to environmental factors are not uniform across vertebrate taxa. Instead, species distributions are shaped by a combination of shared functional constraints and lineage-specific ecological traits. Our findings highlight the importance of vertical forest structure and suggest that habitat alteration affecting canopy structure may disproportionately impact certain taxa.

ecology↗

bioRxiv2026

Comparative genomics reveals signatures of distinct metabolic strategies and gene loss associated with Hydra immortality

Hydra is a freshwater cnidarian genus that provides a unique comparative model for aging research, contrasting the immortal H. vulgaris with the aging-inducible H. oligactis. Here, we report a high-quality, chromosome-level genome assembly of H. vulgaris strain AEP.JNIG. Our assembly is comparable in quality to existing resources, facilitating the analysis of genomic diversity across laboratory strains. Epigenomic profiling revealed that gene-body hypermethylation correlates with transcriptional stability and the suppression of spurious transcription in evolutionary conserved genes, suggesting an epigenetic mechanism for genomic integrity. Furthermore, comparative genomics demonstrated that while Hydra conserves fundamental Hallmarks of Aging pathways, the immortal H. vulgaris paradoxically lacks canonical anti-aging genes (e.g., Klotho, NAMPT) found in the aging-inducible H. oligactis. Instead, H. vulgaris exhibits a distinct metabolic signature related to mitochondrial energy production and NTP synthesis. Collectively, our comparative genomics results suggest multiple potential mechanisms associated with the H. vulgaris immortality and the aging traits of H. oligactis, providing novel targets for future functional studies. Significance statementWhy do some organisms age while others appear not to? The freshwater animal Hydra provides a unique opportunity to investigate this question, as closely related species display contrasting aging phenotypes. We generated a high-quality genome assembly for a new strain of a non-aging species and conducted comparative analyses with related strains and an aging species. Even closely related strains can accumulate substantial genetic divergence over time, and stable DNA modification patterns were associated with consistent gene activity, suggesting a mechanism that may help maintain cellular balance. Surprisingly, several well-known longevity genes are present in the aging species but absent in the non-aging one. This suggests that extended lifespan may not simply depend on possessing more "anti-aging" genes, but instead may reflect differences in how core biological processes are organized. Our study provides new insights into the genetic basis of aging and highlights Hydra as a powerful model for understanding longevity.

genomics↗

bioRxiv2026

Unravelling historical, taxonomic, and cultural influences on the etymology of scientific names across Animalia

Animal naming is fundamental to scientific communication, yet it also reflects the historical and cultural contexts in which names are bestowed. Scientific names function as taxonomic labels and enduring records of human engagement with nature. Owing to this dual role, species names have recently attracted increasing attention from historical and humanities perspectives, both for their informative value and for the biases they may encode. To objectively assess these patterns at a large scale, we investigated etymological trends across Animalia using a comprehensive dataset of species names. Our analyses reveal that naming practices are shaped by a combination of historical events, taxonomic traditions, and cultural influences. Major global disturbances coincided with marked declines in species descriptions, whereas advances in biological techniques were associated with shifts in naming practices. Furthermore, etymological trends differed among phyla, indicating that taxonomic communities vary in their naming conventions. These differences suggest that taxonomists preferences, shared aesthetics, available knowledge, and cultural biases are differentially preserved in scientific names. Together, our results demonstrate that zoological nomenclature constitutes a valuable archive for understanding the historical and cultural dimensions of taxonomy.

zoology↗

bioRxiv2025

Automated Labeling of Scientific Names and Etymological Trend Analysis in Phytophagous Arthropods Using Large Language Model

Scientific names, especially epithets, are derived from various factors, not only species characteristics but also cultural backgrounds, such as the names of people. They reflect how species were perceived at the time. However, several ethical issues have been raised, such as naming species after criminals and gender imbalance in eponyms (epithets named after people). Previous research has been conducted through thorough literature reviews with random sampling, which requires significant time and effort. In this study, the accuracy of the automated labeling using a Large Language Model (LLM) was assessed, and the temporal etymological trends of 2,705 species of phytophagous arthropods were investigated. LLM-based classification achieved F1 scores above 75% and accuracy above 90% in the Morphology, Host, Geography, and People. However, the Ecology & Behavior and Other exhibited accuracy issues. Analyses using the Generalized Additive Model (GAM) revealed shifting naming trends, with a decrease in Morphology and an increase in Geography and People, consistent with previous research on spiders. This study demonstrates the effectiveness of LLM-based classification for epithets and provides a new perspective on the social and scientific debates surrounding scientific names based on etymological trends.

bioinformatics↗