Variation Patterns in Populations of Eastern European Globularia (Plantaginaceae, Magnoliopsida) Species Due to Habitat Conditions

The paper presents the results of studying the morphological and genetic variation in populations of two species from genus Globularia, G. bisnagarica L. and G. trichosantha Fisch. & C.A. Mey. Both species are relicts and have disjunctive ranges. The analysis involved 25 populations of G. bisnagarica and 4 populations of G. trichosantha growing far apart from the main parts of their ranges. Sequencing of some regions of cpDNA (trnL–trnF, rbcL, and rpS16) and nuclear rDNA (ITS barcoding) revealed an extremely low level of genetic variability in the populations of both studied species. At the same time, G. bisnagarica demonstrates genetic uniformity within the entire disjunctive range. A study of the leaf blade shape variation with the geometric morphometrics approach revealed no clear interpopulation differences for both species; in most cases, the shape varied widely at the intrapopulation level. However, in the case of G. bisnagarica, a subtle trend was found: in populations from habitats with southern location, the leaves had a narrow, oblong shape, while the populations located to the north, were characterized by wider, spatulate shape of the leaf blade. The assessment of variation in size parameters of plant organs using classical linear morphometrics revealed a more noticeable separation of populations for both G. bisnagarica and G. trichosantha. Modeling with environmental factors, designed to explain the observed patterns of variation, showed that the linear sizes of plant organs were more affected by climatic and topographic factors than the leaf blade shape. The main drivers of morphological variation in morphometric parameters of G. bisnagarica populations were the elevation, mean diurnal range of temperature, and annual precipitation. Variation in morphometric parameters of G. trichosantha populations mostly were driven by the annual mean temperature. Morphological variation observed in populations of G. bisnagarica within the studied fragments of the disjunctive range has exclusively modification nature and caused by natural climatic factors and local conditions of population growth.