Limitations to reproductive success in the dioecious tree Rhamnus davurica

PLoS One. 2013 Dec 6;8(12):e81140. doi: 10.1371/journal.pone.0081140. eCollection 2013.

Abstract

The reproductive success of a female plant in a dioecious species may be affected by pollen limitation and resource limitation. This study presents evidence that the reproductive success of the dioecious understorey tree species, Rhamnus davurica, is affected by the distance to the nearest male. The sex ratios were female-biased, although showing fluctuations in the three years of conducting the study. The mortality rate of females was higher than that of males indicating a trade-off between reproduction and survival. Altogether 49 females, designated as "focal females", were randomly selected for monitoring their reproductive status between April and October in 2010. But successful reproduction (meaning that the flowering female trees had fruit in the fruiting season) was observed only in 28 females in 2011 and 16 females in 2012. The method of path analysis was applied to determine the effect of topography, local competition and proximity to the nearest male on the fruit set of the females. In the three years of the study, elevation, competition and female size had no significant effect on the fruit set. The distance to the nearest male, however, had a significant effect on fruit set. Number of fruits and fruit set were decreased with increasing distance to the nearest male. It was possible to estimate maximum fruit set, based on the comparatively large dataset. The number of fruits and the fruit set are exponentially related to the distance to the nearest male and the relationships are described by an exponential model. The results of this study support the importance of pollen limitation on the reproductive success in Rhamnus davurica.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Flowers / physiology*
  • Fruit / growth & development
  • Genetic Fitness / physiology*
  • Pollen / physiology*
  • Reproduction
  • Rhamnus / physiology*
  • Seasons
  • Sex Ratio
  • Trees

Grants and funding

This research is supported by the National Science Foundation of China (31200315), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0781), the 12th five-year National Science and Technology plan of China (2012BAC01B03), and the Program of the Co-Construction with Beijing Municipal Government of China (2012).