BIODIVERSITAS ISSN: 1412-033X Volume 16, Number 2, October 2015 E-ISSN: 2085-4722 Pages: 179-187 DOI: 10.13057/biodiv/d160213 Bayesian and Multivariate Analyses of combined molecular and morphological data in Linum austriacum (Linaceae) populations: Evidence for infraspecific taxonomic groups FATIMA AFSHAR 1 , MASOUD SHEIDAI 2 , SEYED-MEHDI TALEBI 3,♥ , MARYAM KESHAVARZI 1 1 Department of Biology, Alzahra University, Tehran, Iran. 2 Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran. 3 Department of Biology, Faculty of Sciences, Arak University, Arak, 38156-8-8349 Iran. Tel. +98-863-4173317. ♥ e-mail: seyedmehdi_talebi@yahoo.com. Manuscript received: 10 May 2015. Revision accepted: 31 July 2015. Abstract. Afshar F, Sheidai M, Talebi SM, Keshavarzi M. 2015. Bayesian and Multivariate Analyses of combined molecular and morphological data in Linum austriacum (Linaceae) populations: Evidence for infraspecific taxonomic groups. Biodiversitas 16: 179- 187. Plant specimens of Linum austriacum (Linaceae) were collected from 16 geographical populations of nine provinces in Iran and used for morphological and molecular (ISSR) analyses. Different multivariate and Bayesian methods were used to study interpopulations differences. Analysis of variance test and Principal coordinate analysis plots indicated morphological difference of the populations. Mantel test revealed positive significant correlation between morphological and geographical distance of these populations. Pearson , coefficient of correlation showed significant correlations between basal leaf length, width and length/width ratio with latitude and altitude of the studied populations. Bayesian analysis of combined molecular and morphological features revealed divergence of the studied populations and consensus tree showed separation of 6 populations in different clusters. Canonical Variate Analysis plot of these populations showed that Sang Sefid and Salmas populations differed greatly from the other populations. New ecotypes are suggested for these populations. Keywords: Infraspecific variation, morphology, Iran, ISSR, population. INTRODUCTION The presence of intraspecific variation in organisms is a source of natural variation and is a way of response of organisms to their environment. Intraspecefic variation brings about biodiversity and is thought as the main origin and storage of speciation (Christine and Monica 1999; Hufford and Mazer 2003). Many plant species have wide geographical distribution and face a wide range of climatic and edaphic conditions. Individuals of these species are able to give appropriate response to a tremendous variety of different conditions. These responses or adaptations change the descents of these individuals of a species, genotypically, phenotypically and physiologically and led to infraspecific diversity. Therefore, descents of these individuals tend to appear as new ecotypes, ecophenes, chemotypes, cytotypes and even subspecies (Christine and Monica 1999). Habitat heterogeneity, combined with natural selection, often results in multiple, genetically distinct ecotypes within a single species. In addition, the populations of a given species facing different environmental conditions may undergo genetic changes to adapt to their local conditions (Linhart and Grant 1996; Hufford and Mazer 2003). Infraspecific variation, difference between individuals or populations of a given species, is responsible for a relation of functionally relevant niche space occupation in biological communities (Albert et al. 2010; Fridley and Grime 2010; Violle et al. 2010). It is confirmed that plants occupy different space to forbear competitive interactions by means of variations in morphological and physiological characteristics. In addition, same plant species elude competition with each other and variegate their biological strategies by means of feature variation. Linum L. genus (Linaceae) contains about 180 species that are source of fiber (Smeder and Liljedahl 1996), seed oils (Diederichsen and Raney 2006), and fodder (Bhathena et al. 2002). Some species are of medicinal value and contain Omega-3 fatty acids and potential anti-cancer compounds (Rogers 1982) as well as Lignans (Schmidt et al. 2010). Linum species grow in temperate and subtropical regions of the world (Rogers 1982; Muir and Westcott 2003). Linum austriacum L. is an herbaceous medicinal plant containing important lignans such as arylnaphthalene lignan and justicidin (Mohagheghzadeh et al. 2002), with antifungal, antiprotozoal, cytotoxic and piscicidal properties (Gertsch et al. 2003). Although extensive biosystematics and phylogenetic studies have been carried out in the genus Linum (see for example, Velasco and Goffman 2000; Everaert et al. 2001; Sharifnia and Albouyeh 2002; Hemmati 2007; Rogers 2008; Schmidt et al. 2010; Soto-Cerda et al. 2011, Talebi et al. 2012a,b), little is known about the infraspecific diversity and taxonomic forms of wild Linum species (Sheidai et al. 2014b).