Biology subjects

Fukasawa, K.

Publications and source records attributed to Fukasawa, K..

9 recordsLinked to original sources

bioRxiv2026

From introduction to eradication: reconstructing population size and removal history of an invasive species

O_LIUnderstanding the processes underlying successful eradication of invasive species is essential for achieving global island conservation goals. Despite the widespread availability of capture records from eradication programs, modeling frameworks that utilize these datasets to elucidate spatio-temporal population dynamics remain underdeveloped. C_LIO_LIIn this study, we reconstructed the spatio-temporal population dynamics of the small Indian mongoose on Amami-Oshima Island (712 km{superscript 2}), Japan, where the species was introduced in 1979 and officially declared eradicated in 2024 after more than 30 years of systematic removal. We integrated introduction records, capture data, and monitoring data using a hierarchical harvest-based model (HBM). To evaluate the models capacity to support management decisions and assess eradication success, we conducted retrospective analyses and compared estimated eradication probabilities with those obtained from a rapid eradication assessment (REA; Samaniego-Herrera et al., 2013). C_LIO_LIThe estimated population size (before reproduction) peaked at 5,449 individuals (95% CI: 4,703, 6,175) in 2000 and subsequently declined almost monotonically. The maximum invaded area was 547.78 km{superscript 2} (posterior median, 95% CI: 496.47, 566.04) in 2009, indicating that the removal program successfully prevented island-wide expansion. Retrospective analyses showed that population estimates remained within the 95% credible intervals of the full dataset estimates, demonstrating temporal consistency. Eradication probabilities estimated by the HBM were substantially higher than those from the REA, highlighting the sensitivity of estimates to fine-scale heterogeneity in detection processes. C_LIO_LISynthesis and applications: Hierarchical HBMs provide a powerful framework for reconstructing, predicting, and evaluating invasive species eradication dynamics. Being aware of the limitations for application to eradication evaluations, HBMs can support adaptive management in long-term eradication programs and improve our understanding of the mechanisms underlying successful eradication. C_LI

ecology↗

bioRxiv2026

A chorionic gonadotropin assay enables non-invasive detection of ovulation and early pregnancy in a New World primate model

Early detection of ovulation and pregnancy in the common marmoset is crucial for reproductive studies, yet hCG kits lack cross-reactivity with marmoset CG, and current methods remain labor-intensive. Here, we developed monoclonal antibodies against marmoset CG and CG{beta}, and established a non-invasive immunochromatographic CG assay. By eliminating invasive blood sampling, this assay supports 3Rs principles and enables practical endocrine monitoring. The assay detected urinary CG surges preceding ovulation, enabling efficient embryo recovery through artificial insemination (75%). Early pregnancy was detected at approximately 17 days post-ovulation. In addition, pregnancy detection in squirrel monkeys suggests conservation of CG features among certain New World primates. Overall, this simple, non-invasive assay provides a practical tool for marmoset research and establishes a foundation for future conservation-oriented reproductive monitoring following appropriate species-specific validation.

physiology↗

bioRxiv2023

Scalable phylogenetic Gaussian process models improve the detectability of environmental signals on extinction risks for many Red List species

1. Conservation biologists have a daunting task of understanding the causes of species decline associated with anthropogenic factors and predicting the extinction risk of a growing number of endangered species. By stabilising estimates with information on closely related species, phylogenetic information among species can bridge gaps in information on species with small sample sizes when modelling large numbers of endangered species. However, modelling many species with the Gaussian process (GP), which underlies the evolutionary process of phylogenetic random effects, remains a challenge owing to the computational burden in estimating the large variance-covariance matrix. 2. Here, we applied a phylogenetic generalised mixed model with random slopes and random intercepts to 1,010 endangered vascular plant taxa in Japan following phylogenetic GPs implemented by nearest neighbour GP (NNGP) approximation. NNGP enables flexibility in changing the proximity on the phylogenetic tree of species from which information is borrowed to stabilise parameter estimates with a realistic computational burden. We evaluated the effectiveness of phylogenetic models by comparing the predictive performance and descriptive power of phylogenetic and non-phylogenetic models and identified the anthropogenic factors contributing to the decline of each of the studied endangered species. 3. We found that the model with phylogenetic information had better prediction performance than the model without phylogenetic information. The results showed that across all explanatory variables, the phylogenetic model could detect interspecific differences in response to environmental factors in a number of species more clearly. Combined with the phylogenetic signal results, we could also detect a phylogenetic bias in the species that could benefit from the positive effects of protected areas but reduce the extinction risk of 95% of all studied taxa. 4. In conclusion, our model, considering phylogenetic information with NNGP, allows the elucidation of factors causing the decline of many endangered species. In future analyses, the estimation of extinction probability linked to environmental change using such modelling might be applied to future climate-land use scenarios, advancing the comprehensive assessment of biodiversity degradation and threats to species at multiple scales.

ecology↗

bioRxiv2023

Distance sampling with vehicle-mounted cameras for the estimation of farmland bird abundance over a wide area.

Farmland bird populations are declining due to farmland abandonment and agricultural intensification. Effective conservation strategies require appropriate monitoring approaches, including efficient and scalable survey methods. In this study, we developed a large-scale monitoring method for herons and egrets (Ardeidae) using vehicle-mounted video cameras and distance sampling models that incorporate location uncertainty. The survey was conducted in and around the evacuation zone of the Fukushima Daiichi nuclear power plant accident. A total of 7,031 km of roadside video footage was recorded, covering 24.41 km{superscript 2} of farmland. Ardeidae were observed only outside the evacuation zone and were entirely absent within it. Predicted abundance differed greatly between areas inside (0.0279 {+/-} 0.0307/km{superscript 2}) and outside (4.57 {+/-} 5.36/km{superscript 2}) the evacuation zone. Incorporating location uncertainty into the distance sampling model had little effect on the estimates (4.57 {+/-} 5.36 vs. 4.51 {+/-} 5.29/km{superscript 2} with and without integrating location uncertainty, respectively). This suggests that our video-based roadside survey method is robust to location uncertainty in structured landscapes such as Japanese rice paddies. The accuracy may be attributed to the study system, where levees and roads divide paddy fields, limiting potential error in observer-target distances Our method can be applied to other open habitats, such as natural grasslands and wetlands, especially in areas lacking artificial markers, by incorporating measurement uncertainty into the model. This combination of roadside surveys with vehicle-mounted cameras and distance sampling provides a practical and transferable approach for monitoring large-bodied species in open landscapes, enhancing both the efficiency and spatial coverage of biodiversity assessments. HighlightsBroad-scale farmland abandonment following the Fukushima Daiichi nuclear power plant accident led to sharp declines in large farmland bird abundance. Efficient large-scale roadside surveys were conducted using vehicle-mounted video cameras. Ardeidae abundance was estimated using distance sampling models that incorporated location uncertainty. The survey method is robust and applicable to open habitats such as farmlands, grasslands, and wetlands.

ecology↗

bioRxiv2023

Mechanistic home range capture-recapture models for the estimation of population density and landscape connectivity

Spatial capture-recapture models (SCRs) provide an integrative statistical tool for analyzing animal movement and population patterns. Although incorporating home range formation with a theoretical basis of animal movement into SCRs can improve the prediction of animal space use in a heterogeneous landscape, this approach is challenging owing to the sparseness of recapture events. In this study, we developed an advection-diffusion capture-recapture model (ADCR), which is an extension of SCRs incorporating home range formation with advection-diffusion formalism, providing a new framework to estimate population density and landscape permeability. we tested the unbiasedness of the estimator using simulated capture-recapture data generated by a step selection function. We also compared accuracy of population density estimates and home range shapes with those from SCR incorporating the least-cost path and basic SCR. In addition, ADCR was applied to real dataset of Asiatic black bear (Ursus thibetanus) in Japan to demonstrate the capacity of the ADCR to detect geographical barriers that constrain animal movements. Population density and permeability of ADCR were substantially unbiased for simulated datasets. ADCR could detect envitonmental signals on connectivity more sensitively and could estimate population density, home range shapes and size variations better than the existing models. For the application to the bear dataset, ADCR could detect the effect of water body as a barrier of movement which is consistent with previous studies, whereas estimates by SCR with the least-cost path was difficult to interplet. ADCR provides unique opportunities to elucidate both individual- and population-level ecological processes from capture-recapture data. By offering a formal link with step selection functions to estimate animal movement, it is suitable for simultaneously modeling with capture-recapture data and animal movement data. This study provides a basis for studies of the interplay between animal movement processes and population patterns.

ecology↗

bioRxiv2022

Higher-order dissimilarity in biodiversity: Identifying dissimilarities of spatial or temporal dissimilarity structures

O_LIElucidating biodiversity patterns and their background processes is critical in biodiversity science. Dissimilarity, which is calculated based on multivariate biological quantities, is a major component of biodiversity. As spatial and temporal biodiversity information availability increases, the scope of dissimilarity studies has been expanded to cover various levels and types of spatio-temporal biodiversity facets (e.g., gene, community, and ecosystem function), and diverse pairwise dissimilarity indices have been developed. However, further development of the dissimilarity concept is required in comparative studies on spatio-temporal structures of biodiversity compositional patterns, such as those exploring commonalities of biogeographical boundaries among taxa, compared to the conventional ones to consider higher dimensions of dissimilarity: dissimilarity of dissimilarity structures. C_LIO_LIThis study proposes a novel and general concept, high-order dissimilarity (HOD), for quantitatively evaluating the dissimilarities of spatial or temporal dissimilarity structures among different datasets, proposes specific implementations of HOD as operational indices, and illustrates the potential resolution of scientific and practical questions through HOD. C_LIO_LIWe further demonstrate the advantages of the HOD concept by applying it to actual patterns, such as long-term and/or large-spatial hypothetical monitoring datasets. C_LIO_LIOur conceptual framework on HOD extends the existing framework of biodiversity science and is versatile, with many potential applications in acquiring more valuable information from ever-increasing biodiversity data. C_LI

ecology↗

bioRxiv2021

Hierarchical trait-based model reveals positive and negative effects of land abandonment on butterfly communities across climatic regions in Japan

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 utilize 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 geographic 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.

ecology↗

bioRxiv2021

SMURF2 phosphorylation at Thr249 modifies the stemness and tumorigenicity of glioma stem cells by regulating TGF-β receptor stability

Glioma stem cells (GSCs) contribute to the pathogenesis of glioblastoma, the most malignant form of glioma. The implication and underlying mechanisms of SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) on the GSC phenotypes remain unknown. We previously demonstrated that SMURF2 phosphorylation at Thr249 (SMURF2Thr249) activates its E3 ubiquitin ligase activity. Here, we demonstrate that SMURF2Thr249 phosphorylation plays an essential role in maintaining GSC stemness and tumorigenicity. SMURF2 silencing augmented the self-renewal potential and tumorgenicity of patient-derived GSCs. The SMURF2Thr249 phosphorylation level was low in human glioblastoma pathology specimens. Introduction of the SMURF2T249A mutant resulted in increased stemness and tumorgenicity of GSCs, recapitulating the SMURF2 silencing. Moreover, the inactivation of SMURF2Thr249 phosphorylation increases TGF-{beta} receptor (TGFBR) protein stability. Indeed, TGFBR1 knockdown markedly counteracted the GSC phenotypes by SMURF2T249A mutant. These findings highlight the importance of SMURF2Thr249 phosphorylation in maintaining GSC phenotypes, thereby demonstrating a potential target for GSC-directed therapy.

cancer biology↗

bioRxiv2018

Characterization of oral microbiota in marmosets: feasibility of using the marmoset as a human oral disease model

As the worlds population is aging, there is an increasing demand for research regarding aging and aging-related disorders, to achieve better understanding of aging. Ideally, such research would be performed with human subjects. However, due to ethical considerations, animals such as rodents and monkeys are used as alternatives. Among these alternative models, non-human primates are preferred because they share common traits with humans. The small South American common marmoset (Callithrix jacchus) may offer a number of advantages over other non-human primates in terms of its relatively small size, short life span, and identical dental anatomy, compared with humans. The purpose of this study was to clarify the viability of using the marmoset as a human oral disease model.\n\nWe collected saliva samples from eight common marmosets and eight human subjects. Prokaryotic DNA was extracted from the saliva samples, and 16S bacterial rRNA gene sequencing was performed on each of the samples. Our results indicated that the types of oral microbiomes detected among human and marmoset samples were nearly identical. In contrast, the oral microbiomes of our human and marmoset subjects were distinctly different from those of rat and dogs, which are popular animal models. The oral microbiomes of marmosets showed greater diversity than those of humans. With respect to individual variation, marmosets exhibited less variation in their oral flora, compared with humans. This difference in variation might be attributed to the fact that marmoset subjects were kept in a controlled environment with identical lifestyles.\n\nThe characteristics of its oral microbiota, combined with other technical advantages, suggest that the marmoset may provide the best animal model thus far for the study of oral health. This study characterized the oral microbes of the marmoset, thereby providing information to support future application of the marmoset as a model for age-related oral disease.

microbiology↗