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Evolutionary Ecology

, 21:173 | Cite as

Outcrossing increases infection success in the holoparasitic mistletoe Tristerix aphyllus (Loranthaceae)

  • Wilfredo L. Gonzáles
  • Lorena H. Suárez
  • Rodrigo Medel
Original paper

Abstract

Most studies on the fitness advantage of outbreeding in host–parasite systems have been assessed from the host rather than the parasite perspective. Here, we performed experimental pollination treatments to evaluate the consequences of outbreeding on fitness-related traits in the holoparasitic mistletoe Tristerix aphyllus in a 2-year field study. Results indicate that self-pollinated plants had a lower fruit production than outcrossed plants (20.4% and 29.5% reduction in 2002 and 2003, respectively), and resulting inbred fruits were smaller than outcrossed fruits in both years. No effect was detected for seed mass. The percentage of germination of inbred seeds was 15.1% and 6.0% lower than outcrossed seeds in 2002 and 2003, respectively. Inbred seedlings had shorter radicles, which translated to a 71.6% and 60.0% reduction in infection success compared with outcrossed plants in 2002 and 2003, respectively. Overall, our results revealed significant inbreeding depression on almost every trait that was examined. Although the mean value of traits varied from a year to another, the magnitude of inbreeding depression did not change significantly between years. Our findings constitute the first evidence that outcrossing increases infection success and probably virulence in parasitic plant populations.

Keywords

Host–parasite interactions Inbreeding depression Radicle Selfing Outcrossing Chile Cacti 

Notes

Acknowledgments

We thank N. Peña, C. Neely, P. Caballero, and C. Ossa for their assistance during the fieldwork and E. Gianoli and three anonymous reviewers for helpful comments on a previous version of this manuscript. Special thanks to CONAF for allowing us to work at Las Chinchillas National Reserve and for logistic support provided during this research. WLG was supported by a CONICYT doctoral fellowship. This work was partially funded by FONDECYT 1010660, and the Center for Advanced Studies in Ecology and Research in Biodiversity supported by the Millennium Science Initiative (P99-103F ICM).

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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Wilfredo L. Gonzáles
    • 1
  • Lorena H. Suárez
    • 1
  • Rodrigo Medel
    • 2
  1. 1.Departamento de BotánicaUniversidad de ConcepciónConcepciónChile
  2. 2.Departamento de Ciencias Ecológicas, Facultad de CienciasUniversidad de ChileSantiagoChile

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