Genetic and morphological variability in Cattleya elongata Barb. Rodr. (Orchidaceae), endemic to the campo rupestre vegetation in northeastern Brazil

Abstract

Cattleya elongata is a rupicolous orchid species spread throughout and endemic to outcrop islands in campo rupestre vegetation of the Chapada Diamantina, northeastern Brazil. We scored nine natural populations of C. elongata for morphological and genetic variability, covering the whole distribution area of the species, using allozymes and ISSR markers and morphometric multivariate analyses. Genetic variability in allozimes was relatively high (H e = 0.12–0.25), and unexpectedly higher than the values based on ISSR (H e = 0.16–0.19). The populations present moderate structuring (allozymes, ΦPT = 0.14; ISSR, ΦPT = 0.18) and low inbreeding (allozymes, F IS = 0.06). Genetic similarity among the populations was high in both markers, in spite of the discontinuity of the outcrops of the Chapada Diamantina. We found no particular biogeographical pattern to the distribution of the genetic and morphologic similarity among the populations of C. elongata. We found high morphological variability with moderate differentiation among the populations. We did not find any correlation among genetic, morphological, and geographical distances, and among the variability found in the morphological and genetic markers. The differences observed between the two genetic markers and the various morphological markers examined here indicated that the isolated use of any single parameter of these different populations for conservation planning or management would not consider all of the variability to be found in the species, as found in other Brazilian campos rupestres plants.