Genetic structure and mating systems of metallicolous and nonmetallicolous populations of Thlaspi caerulescens
Article first published online: 3 MAR 2003
Volume 157, Issue 3, pages 633–641, March 2003
How to Cite
Dubois, S., Cheptou, P.-O., Petit, C., Meerts, P., Poncelet, M., Vekemans, X., Lefèbvre, C. and Escarré, J. (2003), Genetic structure and mating systems of metallicolous and nonmetallicolous populations of Thlaspi caerulescens. New Phytologist, 157: 633–641. doi: 10.1046/j.1469-8137.2003.00684.x
- Issue published online: 3 MAR 2003
- Article first published online: 3 MAR 2003
- Received: 27 August 2002 Accepted: 16 November 2002
- reproductive system;
- genetic differentiation;
- pollen : ovule ratios;
- gene flow;
- heavy metals
- • Genetic variation structure and breeding system were investigated in metallicolous (MET) and nonmetallicolous (NONMET) populations of the heavy-metal hyperaccumulator Thlaspi caerulescens from Belgium, Luxembourg and the French Mediterranean region.
- • Allozyme variation showed a clear differentiation between the two ecotypes in Belgium and Luxembourg but not in southern France, in line with the lower degree of geographical isolation between the two ecotypes in this region.
- • In both regions inbreeding coefficient (FIS) of NONMET populations was significantly higher compared to MET populations. Pollen/Ovule ratios were significantly higher in MET compared with NONMET populations.
- • These results suggest that NONMET populations of T. caerulescens are more self-fertile than their MET counterparts. This contrasts with earlier studies on other metal-tolerant species in which selfing rates were higher in MET populations. This pattern may be explained by the fact that both ecotypes are not in sympatry in the populations studied, and therefore reproductive isolation has not been selected to maintain the adaptations to metal-contaminated soils. In addition, higher selfing rates in NONMET populations may have evolved as a mechanism of reproductive assurance, because these populations generally are at low densities.