Evolutionary Ecology

, Volume 24, Issue 6, pp 1399–1415 | Cite as

Fine-scale spatial structure of genets and sexes in the dioecious plant Dioscorea japonica, which disperses by both bulbils and seeds

  • Inoue Mizuki
  • Kiyoshi Ishida
  • Naoki Tani
  • Yoshihiko Tsumura
Original Paper


To understand the evolution of clonal reproduction and the diversity of clonal plants, it is necessary to clarify the characteristics of each clonal habit. There has been little research on whether bulbils alter spatial genetic structure (SGS) because of the lack of connection to maternal ramets. We used simple-sequence-repeat (SSR) markers to determine the fine-scale SGS of the dioecious plant Dioscorea japonica, which disperses both as bulbils and as seeds. We also evaluated the contributions of sexual and clonal reproduction and tested for spatial sex segregation (SSS). We discovered 111 genets from 394 ramets in a 2.8-ha plot. Genotypic richness (R = 0.28) and clonal diversity (Simpson’s D = 0.94, Fager’s E = 0.90) were high. We did not find SSS, suggesting that the population does not suffer from a shortage of mating pairs due to clonal reproduction. The Sp values revealed moderate SGS at the genet level (Sp = 0.013–0.014), and the genets intermingled at a local scale. Significant SGS at the ramet level showed that ramets within the same genet tended to aggregate. We also found a skewed clonal spatial distribution. The spatial extent of genets was positively correlated with the number of ramets within a genet. The contribution of bulbil production to the variance of parent–offspring gene dispersal was about one–fifth the contribution from sexual reproduction. These results suggest that the dispersal via bulbils affects the SGS in D. japonica, although its contribution to gene dispersal is small compared to the contribution of sexual reproduction.


Clonal Dioscoreaceae Spatial genetic structure Spatial sex segregation SSR Genet 



Financial support was provided by a JSPS Fellowship (No. 16000940) from the Japanese Society for the Promotion of Science. Yong scientist financial supports of Dep of Biol Environ, Akita pref University supported to attend the Clonal plant workshop 2009. The authors thank K. Kikuzawa, S. Nanami, D. Fujiki, M. Ikeuchi, N. Tsujimura, A. Kimura, and the staff of Hiruzen Experimental forest station, Tottori University Forest for their support of this study. We are grateful to Oliver Honnay and Hans Jacquemyn for organizing the Clonal plant workshop 2009 and this special issues.


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Inoue Mizuki
    • 1
  • Kiyoshi Ishida
    • 2
  • Naoki Tani
    • 3
  • Yoshihiko Tsumura
    • 4
  1. 1.Laboratory of Forest Science, Department of Biological EnvironmentAkita Prefectural UniversityAkitaJapan
  2. 2.Department of Biology, Faculty of Agriculture and Life ScienceHirosaki UniversityHirosakiJapan
  3. 3.Forestry DivisionJapan International Research Center for Agricultural Sciences (JIRCAS)TsukubaJapan
  4. 4.Department of Forest GeneticsForestry and Forest Products Research InstituteTsukubaJapan

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