PARENT SESSION
Poster Session 36: Genetics / Population Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Clonal diversity and flowering sex ratio of a dioecious clonal plant, Dioscorea japonica (Dioscoreaceae).

Mizuki, Inoue^*,1, Ishida, Kiyoshi², Tani, Naoki³, Tsumura, Yoshihiko⁴, Kikuzawa, Kihachiro⁵, ¹ Kyoto university, Kyoto, Kyoto, Japan² Forestry and Forest Products Research Institute, Kyoto, Kyoto, Japan³ Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan⁴ Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan⁵ Kyoto university, Kyoto, Kyoto, Japan

ABSTRACT- We predict that (1) the patches of clonal plants which produce bulbils would exhibit higher genotypic diversity than those of clonal plants which produce stolons or rhizomes, because individual bulbils are completely independent of other ramets, (2) if clonal plants regenerate not only by bulbils but also by seeds, the probability (P_m) that the most neighboring ramets for individual ramets are the same genet depends on the relative success of the bulbil reproduction. We studied 60 flowering ramets of dioecious clonal plants, Dioscorea japonica, in 2003, and 96 flowering and 330 non-flowering ramets in 2004 at Hiruzen, Japan, using microsatellite markers. The clonal diversity within patches was high (Simpson's D = 0.89, Fager's E= 0.88 for flowering ramets on 2003), supporting the prediction (1). The probability P_m increased with the genet size. There were three small patches which had a few genets, and a large patch which included many genets of both sexes. These results indicate large contribution of bulbil reproduction compare to sexual reproduction. We also measured the relatedness between genets within patches (high relatedness indicates success of sexual reproduction) and analyzed the sex ratio and spatial pattern of flowering sex, which would affect efficiency of sexual reproduction in clonal dioecious plants. The average relatedness within patches was low, nearly zero. The genet-level sex ratio was not biased, but the ramet-level sex ratio was significantly biased to females. Potential of sexual reproduction would not be low because a large patch had both sexes, although the population did not exhibit high relatedness within patches.

Key words: clonal, dioecious, microsatellite, Dioscoreaceae