Differential effects of reproductive interference by an alien congener on native Taraxacum species |
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Authors: | Sachiko Nishida Koh-Ichi Takakura Takayoshi Nishida Takashi Matsumoto Masahiro M Kanaoka |
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Institution: | (1) The Nagoya University Museum, Furo-cho, Nagoya 464-8601, Japan;(2) Osaka City Institute of Public Health and Environmental Science, 8-34 Tojo-cho, Tennoji-ku, Osaka 543-0026, Japan;(3) Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan;(4) Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Yoshidanihonmatsu-cho, Kyoto 606-8501, Japan;(5) Graduate School of Science, Nagoya University, Furo-cho, Nagoya 464-8601, Japan |
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Abstract: | Reproductive interference (RI) has been suggested to play a critical role in native plant displacement by alien congeners.
However, although co-existence of native and alien congeners may provide an opportunity to refute the RI hypothesis, few studies
have examined such a case. Using a native Japanese dandelion, Taraxacum longeappendiculatum, and a co-existing alien congener, Taraxacum officinale, we tested the hypothesis that differences in RI by the alien between native recipient congeners explain whether a native
will co-exist with or be displaced by an alien. We conducted a field survey to investigate the effects of alien relative abundance
on T. longeappendiculatum seed set, and a hand-pollination experiment to identify the extent of pollen interference by the alien on T. longeappendiculatum. We compared these results with those obtained previously for another Japanese native species, Taraxacum japonicum, which was displaced by the alien. In our field survey, alien relative abundance had little effect on seed set in nearby
T. longeappendiculatum, and hand-pollination with mixed pollen grains produced no substantial decrease in seed set of the native species. Model
selection supported these tendencies; the effect of RI by the alien differed between the two native species. Other potential
factors, such as resource competition or habitat changes, could not explain the co-existence of T. longeappendiculatum with and exclusion of T. japonicum by the alien in the same explanatory framework. Considering the consistent explanatory power, the findings suggest that RI
is a critical mechanism that can determine both co-existence with and displacement of native dandelions by an alien congener. |
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