Two lineages of Trifolium alpinum (Fabaceae) in the Pyrenees: Evidence from random amplified polymorphic DNA (RAPD) markers
Résumé
Trifolium alpinum L. is an important component of the high-elevated grazing ecosystem in the French Pyrenees. To assess population relationships and levels of geographical differentiation of it In this region, we analysed forty populations sampled in ten river catchments by RAPD. Our results indicated intermediate level of genetic diversity in most populations, most of it being attributed to intrapopulation variation after AMOVA. Population differentiation evaluated through FST and exact tests showed that an important genetic differentiation exists among populations. This differentiation is to some extent explained by the occurrence of two divergent groups along the massif that distinguish an eastern and a western pool of T. alpinum populations. Paleoclimatic episodes of the Quaternary, involving altitudinal species migration from glacial refugia, could explain the pattern of neutral diversity observed. Additional factors such as adaptative divergence or species life traits are proposed to explain the maintenance of this pattern through time.