Investigating reproductive incompatibility barriers in a Mediterranean rockrose (Cistus ladanifer)

Abstract

Cistus ladanifer L. (Cistaceae) is a shrubby species, primarily found as a dominant species of the Mediterranean evergreen scrub. Intervarietal (var. ladanifer and var. maculatus) cross compatibility and self-incompatibility (SI) were studied in six Iberian populations of C. ladanifer. In addition, temporal variation in SI across 2 years and variability in the strength of SI throughout the flowering season were analysed in a subset of two populations. The two coloured floral morphs of C. ladanifer were compatible, and pollination had statistically similar ability to fruit set when crossing individuals of the two varieties (440 flowers). Results from hand self-pollination indicate negative self-compatibility, regardless of individuals being sampled from different populations, varieties and years (160 flowers in 2003 and 1620 flowers in 2006). In addition, SI strength did not vary along the flowering season. All these results lead us to argue that, in contrast to the results of its sister species (Cistus salviifolius), the highly polymorphic C. ladanifer possesses an extremely stable SI system but a weak reproductive barrier between varieties.

Keywords::

• Breeding systems
• Cistaceae
• flowering phenology
• multipopulation approach
• spatial and temporal variation

Acknowledgements

The authors thank Emilio Cano for field assistance and three anonymous reviewers for helpful discussion on the manuscript. This research was supported by the Spanish Dirección General de Investigación y Técnica (DGICYT) through the project CGL2005-06017-C02 and by the Comunidad de Madrid through the project GR/AMB/0759/2004 and a PhD scholarship to B.G.