POPULATION GENETIC STRUCTURE OF IRIS PUMILA L. IN UKRAINE: EFFECTS OF HABITAT FRAGMENTATION

Habitat fragmentation is one of serious threats to biodiversity of nature in today's world. The present study of a typical steppe species Iris pumila L. (Iridaceae) has analyzed the impacts of geographical isolation and population size on genetic diversity and population structure in conditions of habitat fragmentation. The key indices of population genetic variability calculated from the ISSR markers data were on average as follows: Shannon diversity index (S) - 0.188; unbiased Nei's gene diversity (H-e) - 0.123; and the average measure of Jaccard's genetic distances between individuals within populations - 58.4%. Although the largest population had significantly higher values of S and He, the small and marginal populations also showed a comparable level of variation. Most of the genetic variation of I. pumila was distributed within the populations. A strong correlation was found between Nei's genetic distances and geographic distances between the populations. According to the Bayesian analysis, genetic structure of the populations was highly homogeneous; however, the presence of admixed genotypes indicated the possibility of gene flow between the populations at present.