Biodiv Sci ›› 2012, Vol. 20 ›› Issue (3): 386-390.DOI: 10.3724/SP.J.1003.2012.05041

Special Issue: 传粉生物学:理论探讨与初步实践

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Male biased sex allocation with plant size in gynomonoecious Aster ageratoides

Xingyue Ge, Biru Zhu*(), Wanjin Liao   

  1. Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Beijing Normal University, Beijing 100875
  • Received:2012-02-02 Accepted:2012-03-20 Online:2012-05-20 Published:2012-05-09
  • Contact: Biru Zhu

Abstract:

Classic size-dependent sex allocation models for animal-pollinated plants predict that female allocation increases with plant size. However, some studies have shown a male biased size-dependent sex allocation at flowering stage. We investigated the size-dependent sex allocation strategies within flower and inflorescence in gynomonoecious Aster ageratoides within two naturally-occurring populations in which hermaphroditic and female flowers occur in the same individual. At the flowering stage, male biased size-dependent sex allocation has been observed at both flower and inflorescence level. The pollen/ovule ratio ranged from 750 to 5,250, with a mean of 2,757.14± 206.635, and increased significantly with plant height in one of the populations. At the inflorescence level, the male allocation, which was measured by the proportion of hermaphroditic flowers, increased with plant height in both populations. These results are consistent with the expectation of male biased size-dependent sex allocation at flowering stage, through which A. ageratoides may maximize fitness by enhancing pollen dispersal.

Key words: Aster ageratoides, gynomonoecy, pollen/ovule ratio, single-ovule flower, size-dependent sex allocation