Data from: Sexually antagonistic evolution caused by male-male competition in the pistil

While sexual selection and sexual conflict are important evolutionary
forces in animals, their significance in plants is uncertain. In
hermaphroditic organisms, such as many plants, sexual conflict may occur
both between mating partners (inter-locus conflict) and between male and
female sex roles within an individual (intra-locus conflict). We performed
experimental evolution, involving lines that were crossed with either one
or two pollen donors (monogamous or polyandrous lines), in the
hermaphroditic plant (Collinsia heterophylla) where early fertilizations
are associated with female fitness costs (reduced seed set). Artificial
polyandry for four generations resulted in enhanced pollen performance and
increased female fitness costs compared to the monogamous and source
(starting material) lines. Female fitness was also reduced in the
monogamous line, indicating a possible trade-off between sex roles,
resulting from early pollination. We performed a second experiment to
investigate a potential harming effect of pollen performance on seed set.
We found that high siring success of early-arriving pollen competing with
later-arriving pollen was associated with high female fitness costs,
consistent with an inter-locus sexual conflict. Our study provides
evidence for the importance of sexual selection in shaping evolution of
plant reproductive strategies, but also pinpoints the complexity of sexual
conflict in hermaphroditic species.