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Complex pattern of morphological and genome size variation in <i>Dianthus sylvestris</i> Wulfen <i>s.l.</i> (Caryophyllaceae)

Dianthus sylvestris includes ten subspecies, whose delimitation is challenging and taxonomically inconsistent. Its main diversity centres are the Balkan and the Apennine Peninsulas where the taxa grow in various habitats from the Mediterranean coast to the alpine belt. This study is focused on the Balkan populations where six subspecies occur. In total 162 populations were sampled across the Balkans: 97 were included in detailed morphometric analyses, for 162, including 28 populations from the Alps, relative genome size (RGS) analysed was estimated using flow cytometry, while all Balkan populations were used in the environmental niche analyses. The integrated results of these analyses represent a first step toward the revised taxonomic treatment for D. sylvestris on the Balkan Peninsula. The results reveal that morphological variation gradually changes with environment and geography and does not correspond to described subspecies. The results suggest two morphologically distinct entities, the north-western and the south-eastern groups of populations, distinct by the shape of epicalyx scales, calyx length and petal denticulation. The quantitative assessment of niche overlap, equivalency and similarity of D. sylvestris subspecies indicated, that niche similarity was more common than niche divergence. Longitude was a major geographic predictor associated with morphological variability, where the changes in cauline leaf length and shape of epicalyx scales reflected a gradual transition from the coastal Mediterranean to the alpine environment. RGS analyses revealed that the majority of populations is diploid (2n=2x=30), but also spatially restricted occurrence of tetraploid populations (2n=4x=60) disclosed polyploidization in the NW Balkans. The tetraploid populations are morphologically similar to their diploid counterparts occurring in the same area indicating their autopolyploid origin. The populations at the southern distribution margin in the Balkan Peninsula, as well as those in the central and western parts of the Alps, exhibit higher RGS, likely corresponding to discrete evolutionary lineages.

Balkan Peninsula, morphometrics, environmental niche, flow cytometry

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