Abstract

In order to study the cytological variation between Iranian native Thymus, karyotypes of two taxa (16 populations) from different geographic origins were presented. The ploidy level was different in populations belonging to T. kotschyanus (2x and 4x), but the same level was found (2x) in T. daenensis populations. According to intrachromosomal asymmetry, T. daenensis (10534) had the most asymmetrical and evolutionary karyotype and T. kotschyanus (10513) had the most symmetrical karyotype in all of the populations. While based on interchromosomal asymmetry, among diploid populations, T. daenensis (10535) and among tetraploid populations, only T. kotschyanus (10515) had the most asymmetrical karyotype. In terms of the Stebbins’ system, the karyotype were of populations seizes 1A classes. The results of analysis of variance revealed significant differences between the populations based on all karyotypic characteristics (P<%1). The results of cluster analysis showed that populations of each species T. daenensis and T. kotschyanus have been grouped in separate cluster. The results seemed to provide enough genetic evidence to identify the species and useful data to clarify the interspecific relationships. Detailed karyotype analysis allows us to group the different populations and to specify their relationships.

Key words: Chromosome, karyotype, ploidy, principal components analysis, Thyme.