Genetic diversity in the Carex jamesii complex (Cyperaceae: sect. Phyllostachyae) with insights into the evolution and origin of the newly described species Carex timida

摘要

The Carex jamesii complex is composed of three species: C. jamesii, C. juniperorum, and C. timida. Despite the morphological similarity of C.jamesii and C. timida, these two taxa are not closely linked in a cluster analysis using genetic identity values. Rather, C. timida is grouped with C. juniperorum. The close genetic similarity between these two species confirms the findings of a previous phylogenetic study that showed that C. juniperorum and C. timida are sister species. Carex timida populations from the Ouachita Mountains of Arkansas are genetically unique and blur the distinctiveness between the latter species and C. juniperorum. Such a finding could be a sampling artifact. Alternatively, the plants found in the Ouachita Mountains may be closest to the ancestor that gave rise to C. juniperorum and C. timida. A comparison of genetic, phylogenetic, and phenetic relationships provides insights into the delineation of infraspecific taxa and justification for the recognition of C. timida at thespecies level.