Evidence of genetic differentiation and karyotype evolution of the sedges Cyperus ligularis L. and C. odoratus L. (Cyperaceae)

Abstract

Th e taxonomy of Cyperaceae is complex, with genera like Cyperus harboring species complexes. We analyzed the genetic similarity between Cyperus ligularis L. and C. odoratus L. based on DNA fi ngerprinting and cytogenetics. Signifi cative genetic diff erentiation (G ST = 0.363) and low gene fl ow (N m = 0.877) indicated a clear genetic distinction between the two species. Moreover, the clustering analysis showed two distinct genetic groups, suggesting a lack of evidence for hybridization. Th e phenogram revealed two diff erent lineages, and although all individuals of C. odoratus were collected from plots close to each other, they possessed greater genetic diversity than that observed among individuals of C. ligularis, which were sampled over a wider geographic range. Variation in chromosome number within the two species exhibited the opposite pattern, indicating greater karyotype stability in C. odoratus with 2n = 72 and 2n = 76, while the diploid number for C. ligularis varied from 2n = 66 to 88. Th e lower genetic variation in C. ligularis may be a result of the founder eff ect associated with seed dispersion and clonal reproduction. Field observations and analysis of reproductive biology should enrich the understanding of the genetic structure of the investigated populations and their role in successional processes.