The functional significance of synchronous protandry in Alstroemeria aurea.

HARDER, L. Y M.A. AIZEN

FUNCTIONAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2004 vol. 18 p. 467 - 474

0269-8463

1.Synchronous dichogamy, the simultaneous change in sex phases of all flowers in aninflorescence or entire plant, has been proposed to reduce self-pollination betweenflowers within a plant (geitonogamy) and so should leave more pollen for export and/or reduce inbreeding. We tested these hypotheses withAlstroemeria aureaGraham, aself-compatible, clonal herb with synchronous protandrous inflorescences.2.We manipulatedA. aureainflorescences to compare pollen export, pollen receiptand pollen-tube attrition in synchronous and asynchronous inflorescences. We constructedasynchronous inflorescences by tying together female- and male-phase rametswhich were collected within 1 m of each other and so had a high probability of beinggenetically related.3.Inflorescences with both male- and female-phase flowers received 27% more pollenthan synchronous inflorescences, which was associated with higher pollen-tube attrition.The selfing suggested by these results would reduce genetic contributions to thenext generation as a result of the strong inbreeding depression found in this species.4.In contrast, we found no evidence that asynchronous inflorescences exported lesspollen to companion female-phase inflorescences than did synchronous inflorescences.5.Our results suggest that synchronous dichogamy evolves primarily as an anti-selfingmechanism, rather than to promote outcross siring success.