Kajita Tadashi




Researcher Number(JSPS Kakenhi)


Homepage URL


Current Affiliation Organization 【 display / non-display

  • Concurrently   University of the Ryukyus   Graduate School of Agriculture   Professor  

  • Concurrently   University of the Ryukyus   The United Graduate School of Agricultural Sciences, Kagoshima University   Professor  

  • Duty   University of the Ryukyus   Tropical Biosphere Research Center   Professor  

University 【 display / non-display


    Tohoku University   Faculty of Science   Graduated

Graduate School 【 display / non-display


    Tohoku University  Graduate School, Division of Natural Science  Doctor's Course (first term)  Completed


    Tohoku University  Graduate School, Division of Natural Science  Doctor's Course (second term)  Completed

External Career 【 display / non-display

  • 2015.05

    University of the Ryukyus, Tropical Biosphere Research Center, Professor  

Research Interests 【 display / non-display

  • 分子系統学

  • 保全生物学

  • マングローブ

  • マメ科

  • Sea-dispersal

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Research Areas 【 display / non-display

  • Life Science / Biodiversity and systematics

Published Papers 【 display / non-display

  • Prospects and challenges of environmental DNA (eDNA) metabarcoding in mangrove restoration in Southeast Asia

    Alison K. S. Wee, Severino G. Salmo Iii, Kannan Sivakumar, Amy Y-H Then, Mohammad Basyuni, Jean Fall, Kazi Ahsan Habib, Yukinobu Isowa, Venus Leopardas, Nasreen Peer, Maria D. Artigas-Ramirez, Kithsiri Ranawana, Itchika Sivaipram, Monica Suleiman, Tadashi Kajita

    FRONTIERS IN MARINE SCIENCE ( FRONTIERS MEDIA SA )  10   2023.02 [ Peer Review Accepted ]

    Type of publication: Research paper (other science council materials etc.)

     View Summary

    Species detection using environmental DNA (eDNA) is a biomonitoring tool that can be widely applied to mangrove restoration and management. Compared to traditional surveys that are taxa-specific and time-consuming, eDNA metabarcoding offers a rapid, non-invasive and cost-efficient method for monitoring mangrove biodiversity and characterising the spatio-temporal distribution of multiple taxa simultaneously. General guidelines for eDNA metabarcoding are well-established for aquatic systems, but habitat-specific guidelines are still lacking. Mangrove habitats, as priority ecosystems for restoration in Southeast Asia, present unique prospects and challenges in these regards. Environmental DNA metabarcoding can be used to (1) track functional recovery in ecological restoration, (2) prioritise conservation areas, (3) provide early warning for threats, (4) monitor threatened taxa, (5) monitor response to climate change, and (6) support community-based restoration. However, these potential applications have yet been realized in Southeast Asia due to (1) technical challenges, (2) lack of standardised methods, (3) spatio-temporal difficulties in defining community, (4) data limitations, and (5) lack of funding, infrastructure and technical capacity. Successful implementation of eDNA metabarcoding in mangrove restoration activities would encourage the development of data-driven coastal management and equitable conservation programs. Eventually, this would promote Southeast Asia's shared regional interests in food security, coastal defence and biodiversity conservation.

  • Spatiotemporal process of long-distance seed dispersal in a pantropically distributed sea hibiscus group.

    Yamazaki Y, Kajita T, Takayama K

    Molecular ecology ( WILEY )  32 ( 7 ) 1726 - 1738   2023.01 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Long-distance dispersal (LDD) of seeds plays an essential role in the migration of plants to a new habitat and maintaining gene flow among geographically isolated populations. Pantropical plants with sea-drifted seeds, which have one of the largest distributions in all flowering plants, have achieved their global distribution by LDD. However, the spatiotemporal processes to achieve the wide distribution and the role of LDD in it have not yet been elucidated. In this study, we conducted phylogenomic analyses on the plastome, genome-wide nuclear SNP, and low-copy gene data of Hibiscus tiliaceus and its relatives. The dated phylogeny suggested that global expansion started approximately 4 million years ago (Ma), and species diversification occurred 1 Ma. Plastome phylogeny confirmed the nonmonophyly of the haplotypes in the two widely distributed coastal species, H. tiliaceus and H. pernambucensis. In contrast, genome-wide nuclear SNP phylogenies demonstrated clear genetic segregation among species and/or geographical regions. Ancestral polymorphisms in chloroplast genomes shared among widely distributed species have remained below the range of rapid expansion and speciation of marginal populations. This study demonstrated that the LDD of sea-drifted seeds contributed to the rapid expansion and pantropical distribution of sea hibiscus in the last few million years, and adaptation to local environment or isolation by regional effect after LDD promoted speciation, suppressing gene flow.

  • The role of oceanic currents in the dispersal and connectivity of the mangrove Rhizophora mangle on the Southwest Atlantic region

    André Guilherme Madeira, Yoshiaki Tsuda, Yukio Nagano, Takaya Iwasaki, Maria Zucchi, Tadashi Kajita, Gustavo Mori

    ( Authorea, Inc. )    2022.12

    Type of publication: Research paper (other science council materials etc.)

     View Summary

    <p id="p1">Dispersal is a crucial mechanism to living beings, allowing them toreach new resources such that populations and species can explore newenvironments. However, directly observing the dispersal mechanisms ofwidespread species can be costly or even impracticable, which is thecase for mangrove trees. The influence of ocean currents on themangroves' propagules' movement has been increasingly evident; however,few studies mechanistically relate the patterns of populationdistribution with the dispersal by oceanic currents under an integratedframework. Here, we evaluate the role of oceanic currents on dispersaland connectivity of Rhizophora mangle along the SouthwestAtlantic. We inferred population genetic structure and migration ratesbased on single nucleotide polymorphisms, simulated the displacement ofpropagules along the region and tested our hypotheses with Mantel testsand redundancy analysis. We observed a two populations structure, northand south, which is corroborated by other studies with Rhizophoraand other coastal plants. The inferred recent migration rates do notindicate gene flow between the sampled sites. Conversely, long-termmigration rates were low across groups and contrasting dispersalpatterns within each one, which is consistent with long-distancedispersal events. Our hypothesis tests suggests that both isolation bydistance and isolation by oceanography (derived from the oceaniccurrents) can explain the neutral genetic variation of R. manglein the region. Our findings expand current knowledge of mangroveconnectivity and highlight how the association of molecular methods withoceanographic simulations improve the interpretation power of thedispersal process, which has ecological and evolutionary implications.</p>

  • Analysis of human clinical and environmental Leptospira to elucidate the eco-epidemiology of leptospirosis in Yaeyama, subtropical Japan.

    Sato Y, Hermawan I, Kakita T, Okano S, Imai H, Nagai H, Kimura R, Yamashiro T, Kajita T, Toma C

    PLoS neglected tropical diseases   16 ( 3 ) e0010234   2022.03 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

  • Correlations between allocation to foliar phosphorus fractions and maintenance of photosynthetic integrity in six mangrove populations as affected by chilling.

    Yan L, Sunoj VSJ, Short AW, Lambers H, Elsheery NI, Kajita T, Wee AKS, Cao KF

    The New phytologist ( WILEY )  232 ( 6 ) 2267 - 2282   2021.12 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Chilling restrains the distribution of mangroves. We tested whether foliar phosphorus (P) fractions and gene expression are associated with cold tolerance in mangrove species. We exposed seedlings of six mangrove populations from different latitudes to favorable, chilling and recovery treatments, and measured their foliar P concentrations and fractions, photochemistry, nighttime respiration, and gene expression. A Kandelia obovata (KO; 26.45 degrees N) population completely and a Bruguiera gymnorhiza (Guangxi) (BGG; 21.50 degrees N) population partially (30%) survived chilling. Avicennia marina (24.29 degrees N), and other B. gymnorhiza (26.66 degrees N, 24.40 degrees N, and 19.62 degrees N) populations died after chilling. Photosystems of KO and photosystem I of BGG were least injured. During chilling, leaf P fractions, except nucleic acid P in three populations, declined and photoinhibition and nighttime respiration increased in all populations, with the greatest impact in B. gymnorhiza. Leaf nucleic acid P was positively correlated with photochemical efficiency during recovery and nighttime respiration across populations for each treatment. Relatively high concentrations of nucleic acid P and metabolite P were associated with stronger chilling tolerance in KO. Bruguiera gymnorhiza exhibited relatively low concentrations of organic P in favorable and chilling conditions, but its partially survived population showed stronger compensation in nucleic acid P and Pi concentrations and gene expression during recovery.

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Other Papers 【 display / non-display

Work 【 display / non-display

  • Field works for the study of patropic sea-current seed dispersal plants


  • Phylogegraphical study of pantropic sea-current seed dispersal plants


  • Molecular systematic study of Desmodieae(Leguminosae)