High genetic divergence and low genetic variability in disjunct populations of the endemic Vellozia compacta (Velloziaceae) occurring in two edaphic environments of Brazilian campos rupestres

Abstract

Vellozia compacta Mart. ex Schult. is a morphologically polymorphic species distributed in disjunct populations in two edaphic environments of Brazilian campos rupestres vegetation (rupestrian fields), quartzite outcrops and ferruginous outcrops (canga). These environments have extreme conditions that may lead to local adaptation, especially in canga, due to soils that have large amounts of compounds that are toxic to many plant species. We studied the genetic diversity of ten populations of V. compacta to test the hypothesis its genetic variability is highly structured due to the disjunction of campos rupestres where this species occurs, and the genetic structure is associated with the rock type of the outcrop. Populations from ferruginous outcrops presented about half the genetic diversity (average H e = 0.07) of those of quartzite populations (average H e = 0.13). The populations are divided into six genetic groups and genetic divergence among populations was very high (ΦST = 0.559). The high genetic divergence found can be explained by the disjunct distribution of the populations and the different edaphic conditions. The morphological polymorphism and high divergence among populations indicate that V. compacta might be a complex of incipient or cryptic species and its conservation is of special concern.