Globularia bisnagarica L. (Plantaginaceae) shows genetic uniformity throughout its disjunctive range

The paper presents the results of studying the morphological and genetic variation in populations of two species from genus Globularia, Globularia bisnagarica L. and Globularia trichosantha Fisch. and May. 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 populatio..., Morphometric analysis
The material was collected in 2021–2022 from twenty-five G. bisnagarica and four G. trichosantha populations (Table 1, Fig. 1). Previously, the spatial structure of some of these populations was studied (Kondratieva et al., 2021).
The studied populations were separated into several groups depending on the type and geographical location of the topographic features, to which their habitats are confined. Six groups were identified for G. bisnagarica: Volga Upland (VU), Sokskiye Yary (SYA), Bugulma-Belebey Upland (BBU), Obshchy Syrt (OS), Zilair Plateau (ZP), and Stavropol Upland (SU). G. trichosantha populations were divided into 2 groups: Greater Caucasus (GC) and Crimean Mountains (CM).
For the linear morphometrics approach, the sixteen quantitative morphometric parameters of vegetative and generative organs were measured for 17–30 individuals in each population. These parameters included: number of rosettes, diameter of rosettes, number of leaves per rosette, lengt...,