Morphological and genetic variation in natural populations of Quercus vulcanica and Q. frainetto

Abstract

Quercus vulcanica, an endemic species with scattered distribution, and Q. frainetto are naturally distributed in Turkey. Although they have been reported as closely related species, Q. vulcanica differs from Q. frainetto in the longer petioles and the leaves evenly distributed along the shoots. Knowledge of the amount and distribution of genetic variation in the species and potential hybridization with related species is crucial for the conservation of the species. Therefore, the aims of the study were to analyze leaf morphological and stomatal variation, and to assess patterns of genetic variation at 3 gSSR and 17 expressed sequence tag (EST)-SSR markers within and between four Q. vulcanica and two Q. frainetto populations sampled from Turkey. Based on canonical discriminant and principal component analyses, petiole length, petiole ratio and number of lobes mainly accounted for the discrimination between Q. vulcanica and Q. frainetto. The means of stomatal densities for Q. vulcanica and Q. frainetto were 810 and 862 stomata per mm2, respectively. The mean genetic differentiation between Q. frainetto and Q. vulcanica at 20 microsatellite loci was very low (FST = 0.047). Two loci, 2P24 (FST = 0.119, P = 0.003) and PIE102 (FST = 0.127, P < 0.000), showed comparatively high interspecific differentiation and were identified as outlier loci. Genetic assignment analyses and discriminant analyses based on phenotypic traits assigned most individuals to the one or the other species. Further studies including more populations and genome-wide markers are necessary to assess the level of adaptive genetic variation and potential introgression between Q. vulcanica and other related species.