Late-acting inbreeding depression in both male and female function of Echium vulgare (Boraginaceae)

We present data on late-acting inbreeding depression in pollen performance, siring success and seed production in Echium vulgare. Pollen viability and rate of pollen-tube growth were both lower for pollen from plants derived from selfing than for pollen from plants derived from outcrossing. Pollen t ube numbers within the styles did not differ for pollen from plants derived from selfing or outcrossing. A pollination experiment with two mixtures of pollen from plants derived from selfing or outcrossing, revealed a signifi cant decline of 55% in siring success for pollen from plants derived from s elfing. A second experiment with a complete diallel design revealed inbreed ing depression for both siring success of the offspring (32.8%) and a decli ne in seed production of the offspring (34.8%-40.6%). In addition, results indicated a heritable component for seed number per flower. Offspring fitne ss, measured as seed production and siring ability, can be severely affecte d by late-acting inbreeding depression. Inbreeding depression values for ma le and female functions were not correlated. Both functions must therefore be considered when calculating inbreeding depression.