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Inter- and intrapopulational morphological variability of Elymus repens, a cool-season peren-nial grass and a tenacious weed that spreads both by seeds and rhizomes forming a thick and stout net, was examined. Multivariate statistical analysis of 48 initial morphological characters obtained from 44 population samples (1180 specimens) collected in different habitats revealed the conspicuous variation within E. repens. Principal Component Analysis revealed three extremes of the morphological gradient that were referred to as three varieties of E. repens: var. repens, var. aristatus and var. subulatus, not correlated with the habitat type or geographi-cal location. Canonical Discriminant Analysis proved the taxonomic usefulness of characters such as awned or awnless glumes and lemmas as well as the shape of glumes for variety di-stinction. Results of morphological analysis, in relation to the low level of genetic variation showed in the previous studies, suggest that the extensive morphological variation of E. re-pens can be caused by its plasticity where different morphological patterns are realized on the same genome basis. Additionally, the open-pollinated system of mating results in new combi-nations of morphological characters of plants that further reproduce vegetatively by rhizomes. The nomenclature, taxonomic descriptions and a key to the three varieties are provided.
Fragmented distribution, the breeding system and effects of genetic drift in small-size populations occurring at edge of the species range play an important role in shaping genetic diversity of such a species. Melica transsilvanica is a plant rare in the flora of Poland, where it reaches the northern limit of its continuous range. Amplified Fragment Length Polymorphism (AFLP) DNA profiling method was applied to measure genetic diversity among and within populations of M. transsilvanica. Additionally, genetic relationships between M. transsilvanica and Melica ciliata, two closely related species, were explored. A total of 68 plants from 7 populations of M. transsilvanica and 24 plants from 2 populations of M. ciliata, collected in Poland and outside it, were analyzed. Using 294 AFLP fragments from 3 primer combinations, accessions were grouped into two major clusters associating with M. ciliata and M. transsilvanica, respectively. Further, two subclusters, corresponding to the samples collected from the Pieniny Mts and from the Kraków - Częstochowa Upland were clearly distinguished within the M. transsilvanica group. The hierarchical AMOVA exhibited significant genetic distinction between these geographic regions (60.89%, p < 0.001). The obtained results showed that the most genetic diversity resided between the populations of M. transsilvanica (86.03%) while considerably lower genetic variation was found within the populations (13.97%), which is consistent with the results reported for self-plants. The low level of AFLP genetic variation of M. transsilvanica can be caused by the geographic isolation of populations, which preserves the dominant self-mating breeding system of the species. Individual populations of M. transsilvanica are characterized by isolated gene pools differing by a small number of loci.
A good knowledge of species delimitation is crucial for the biodiversity protection and the conservation of wild species. We studied the efficiency of AFLP markers and morphological characters to assist species determination for Melica ciliata L. and M. transsilvanica Schur within European range of distribution, including isolated and range-limit populations of "M. ciliata" (i.e. M. cf. ciliata) from the Polish Sudetes, where it is regarded as critically endangered. AFLP markers were found to be more effective then morphological characters (more or less continuous) in distinguishing the both studied species. AMOVA revealed very low genetic diversity within populations and high differentiation among populations of M. ciliata and M. transsilvanica (FST = 0.89 and 0.95, respectively). The species-diagnostic AFLP markers of M. transsilvanica shared with "M. ciliata" from the Sudetes were detected. On the other hand, no species-diagnostic genetic markers of M. ciliata or hybrid-diagnostic markers of M. × thuringiaca were found within "M. ciliata". PCoA and NJ showed an overlapping genetic diversity of "M. ciliata" and M. transsilvanica. Hierar­chical AMOVA supported the absence of a significant genotypic distinction between "M. ciliata" and M. transsilvanica. ANOVA showed that the length ratio of lower to upper glumes was the best morphological character to discriminate between M. ciliata and M. transsilvanica. Combined morphological and genetic data show that M. ciliata is not currently present in Poland as its putative Polish populations represent M. transsilvanica. A significant decrease in genetic varia­bility that could influence viability was not observed the in Sudetian populations of M. transsilvanica. However, the population size changes significantly as a result of plant succession. Correction of the northern limit of the continuous distribution of M. ciliata L. in Central Europe is presented.
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