Morphological and genetic distinctiveness of metallicolous and non-metallicolous populations of Armeria maritima s.l. (Plumbaginaceae) in Poland

Patterns of morphological, genetic and epigenetic variation (DNA methylation pattern) were investigated in metallicolous (M) and non-metallicolous (NM) populations of Armeria maritima. A morphological study was carried out using plants from six natural populations grown in a greenhouse. Morphological variation was assessed using seven traits. On the basis of this study, three representative populations were selected for molecular analyses using metAFLP to study sequence- and methylation-based DNA variation. Only one morphological trait (length of outer involucral bracts) was common to both metallicolous populations studied; however, the level of variation was sufficient to differentiate between M and NM populations. Molecular analyses showed the existence of naturally occurring epigenetic variation in A. maritima populations, as well as structuring into distinct between and within population components. We show that patterns of population genetic structure differed depending on the information used in the study. Analysis of sequence-based information data demonstrates the presence of three well-defined and genetically differentiated populations. Methylation-based data show that two major groups of individuals are present, corresponding to the division into M and NM populations. These results were confirmed using different analytical approaches, which suggest that the DNA methylation pattern is similar in both M populations. We hypothesise that epigenetic processes may be involved in microevolution leading to development of M populations in A. maritima.