Sequential variation in the components of reproductive success in the distylous Jasminum fruticans (Oleaceae)
1993
Thompson, J.D. (Centre National de la Recherche Scientifique, Montpellier (France). Centre d'Ecologie Fonctionelle et Evolutive) | Dommee, B.
A 2-year study of three natural populations of the distylous Jasminum fruticans showed that mean fruit and seed production were significantly greater in short-styled plants (thrums) than in long-styled plants (pins). ln this study, we investigated the role of four sequential factors which may differentially influence fruit and seed set in the two floral morphs: (1) differences in flowering phenology, (2) a limitation of pollen transfer towards pins, (3) a differential capacity of the two morphs to act through female and male function and (4) differential fruit abortion in the two morphs. Fruit set was significantly influenced by differences in flowering phenology although there were no differences in flowering time between the two morphs. Supplementary pollinations in a natural population significantly increased fruit set and reduced the difference in fruit set between the two morphs in relation to controls, indicating a limitation on pollen transfer which was most severe towards pin stigmas. In reciprocal crosses, seed set was significantly dependent on the paternal and maternal identity of the pin parent. There was no significant variation among thrums for their performance as male or female parent. Furthermore, individual pin plants with relatively high percentage seed set as female parents gave poor seed set as male parents and vice-versa. Whereas fruit removal had no effect on seed number in thrum plants, a greater proportion of viable seeds were produced on pin plants which were left to naturally mature their fruits than on pins which had fruits artificially removed, suggesting the occurrence of selective fruit abortion in pins but not in thrums.
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