Morphological variability in Chondrilla taxon populations in European Russia and adjacent territories

The morphological variability in populations of Chondrilla taxa is poorly studied, and features of its distribution, both spatially and between taxa, are not obvious. The article presents the results of our comparative analysis of the nature of this variability on the example of 28 populations of eight taxa of the genus in the southeastern European Russia and northwestern Kazakhstan. The variability of eight morphological traits, most of which are still used to determine the species of plants, was analyzed. It is shown that the variability level of these characters, four of which are taxonomically significant, in one year of monitoring is so wide that it completely overlaps the boundaries of their variability of all Eastern European taxa. At the same time, populations of different taxa growing side by side in similar environmental conditions demonstrated a very similar (just identical in some cases) range of morphological variability. It was concluded that the causes of this very dynamic and peculiar variability of traits are most likely the local conditions of population growth in a particular year of monitoring. Our comparative analysis of the interannual (2015, 2016 and 2022) variability of these quantitative traits in 14 populations of five Chondrilla taxa showed its significant dynamics over years as well. Using the method of non-metric multidimensional scaling of quantitative morphometric parameters, it is shown that the gradient of their variability takes place in the direction from the conditions of minimum moisture and maximum temperature to that of increasing humidity and decreasing temperature. At the same time, the combinations of these climatic factors in specific habitats of populations affect the values of morphological parameters to a greater extent than their geographical gradients or taxonomic affiliation.