Abstract
This study investigates the effectiveness of ITS (Internal Transcribed Spacer) DNA barcoding markers for identifying and differentiating eight species of Betula within the Kazakh Altai flora: Betula glandulosa, B. pendula, B. pubescens, B. rotundifolia, B. rezniczenkoana, B. tianschanica, B. microphylla, and B. kirghisorum. By extracting and sequencing DNA from herbarium specimens, the study focuses on assessing the genetic diversity and resolving phylogenetic relationships among these Betula species, many of which have close morphological similarities that can complicate traditional taxonomy. The results reveal that ITS markers provide clear genetic differentiation between these species, highlighting the effectiveness of ITS in distinguishing even closely related species within the Betula genus. Analysis using the Neighbor-Joining method showed two primary clusters, aligning well with known phylogenetic sections, Apterocaryon and Betula, which are established classifications within the genus. Furthermore, the study offers the first ITS sequence data for two species, B. rezniczenkoanaand B. kirghisorum, contributing new genetic information to the NCBI database. These findings are crucial for ongoing conservation efforts, given the ecological and environmental pressures facing native Betula species in the Kazakh Altai. By providing reliable molecular markers, this research supports future studies on species distribution, genetic diversity, and conservation planning within this biodiverse and ecologically sensitive region.