Phylogenetic Relationships and Genetic Diversity of Thai Nepenthes (Nepenthaceae) Revealed by Integrative Molecular Analyses

Accurate assessment of phylogenetic relationships is essential for understanding the evolution, taxonomy, and conservation of the carnivorous genus Nepenthes. In Thailand, species delimitation remains challenging because of extensive morphological variation and the occurrence of several closely related taxa. This study integrated genome-wide single nucleotide polymorphisms (SNPs) generated by Genotyping-by-Sequencing (GBS), chloroplast trnK intron sequences, nuclear ITS sequences, and AFLP markers to investigate phylogenetic relationships and genetic diversity among Thai Nepenthes taxa. Genome-wide SNP analysis recovered three principal clades, whereas trnK and ITS datasets provided complementary resolution at deeper and intermediate phylogenetic levels. The molecular datasets revealed broadly congruent phylogenetic patterns and improved resolution among several closely related Thai taxa. AFLP analysis of Nepenthes mirabilis populations revealed moderate polymorphism despite relatively high overall genetic similarity. Across all datasets, N. mirabilis var. globosa was consistently recovered within the broader N. mirabilis lineage and showed limited genetic differentiation from sampled N. mirabilis accessions. These findings provide an integrated molecular framework for understanding phylogenetic relationships among Thai Nepenthes and support future taxonomic, evolutionary, and conservation studies in the region.