Evol Ecol Res 4: 687-700 (2002)     Full PDF if your library subscribes.

Pollen competitive ability: the effect of proportion in two-donor crosses

Åsa Lankinen* and Io Skogsmyr

Department of Theoretical Ecology, Ecology Building, Lund University, S-223 62 Lund, Sweden

Author to whom all correspondence should be addressed.
e-mail: asa.lankinen@teorekol.lu.se

ABSTRACT

Pollen competitive ability depends on the innate capacity of a pollen donor to produce pollen that reaches the ovules fast, but could also be a consequence of the ability to interfere with pollen from other donors. In a greenhouse study on Viola tricolor, we examined the relative importance of both of these effects by performing crosses where we varied the pollen load composition of two donors. We found that when a pollen donor had higher in vitro pollen tube growth rate than a competitor, this donor sired proportionally more seeds in most cases. At very low proportions, however, there was no benefit of producing fast growing pollen. We further investigated the potential for pollen interactions by comparing in vitro performance in single- and mixed-donor batches of the same density. Pollen tube growth rate differed between treatments in some donor combinations, indicating that pollen from different donors interact. Only donors with the faster growing pollen tubes in the single samples showed signs of interference in the mixtures. Donors with slower pollen tube growth had an increased growth rate when mixed. Although our results suggest interactions between pollen grains from different donors that might affect siring ability, the intrinsic pollen tube growth rate was more important for siring ability in this species.

Keywords: pollen competition, pollen interactions, pollen tube growth rate, sexual selection in plants, Viola tricolor.

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        © 2002 Åsa Lankinen. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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