抄録
Differences in style length among closely related flowering plant species are recognized as a unilateral postmating-prezygotic barrier; species with longer styles prevent pollen fertilization by short-styled congeners. However, little is known about how style length variation within a species affects plant reproduction when exposed to heterospecific pollen. We investigated the relationship between style length in native Oxalis corniculata and hybrid seed formation resulting from interspecific pollination by alien O. dillenii using two O. corniculata populations with large style length variation. We found that the native O. corniculata individuals with longer styles produced hybrid seeds at a lower frequency. In contrast, the effect of style length on seed production following intraspecific pollination conducted as a control treatment was not statistically significant. These results suggest that longer styles of native species can hinder interspecific pollen fertilization owing to physical limitations and mitigate reproductive interference from the alien congener by reducing the cost of ovule loss.
