Genetic and morphological diversity in Cousinia calocephala Jaub. & Spach (Asteraceae; section Cynaroideae bunge) populations

Abstract

The genus Cousinia Cass. of the tribe Cardueae with about 700 species is one of the most diverse genera in Central and SW Asia following Senecio and Vernonia. The section Cynaroideae with 89 species is the largest section of the genus. Cousinia calocephala is the only endemic species of the section distributed in 14 provinces of Iran from Alborz to Zagros mountains. In present study 65 plant specimens of 13 geographical populations of C. calocephala were investigated based on the morphological and genetic (ISSR) data. ANOVA test revealed a significant morphological difference among the studied populations. Similarly, AMOVA test yielded a significant genetic difference between the studied populations, suggesting that the studied populations are morphologically and genetically differentiated. AMOVA test revealed that 94% of the total genetic difference was due to inter-populations genetic differences, while 6% was due to within-species genetic variability. The discriminating power of ISSR loci as determined by Gst against Nm analysis, revealed that almost all ISSR loci have an excellent discriminating power. Thus, ISSR markers are efficient in differentiating of the studied C. calocephala populations. The mantel test, revealed a significant positive correlation between genetic and morphological distance and geographical distance of the studied populations. Genetic analysis results revealed that along with genetic drift, low level of gene flow and migration, adaptive loci also helped populations diverge and adapt these populations to their local condition. Thus, we have three different groups which can be considered as three ecotypes for C. calocephala based on the morphological and genetic data.