Dalbergia latifolia and D. sissoides are economically important and slow growing timber species of India. Both are closely related leguminous species and genetic divergence of these species is still untapped in Kerala and Tamil Nadu states. A total of 56 Dalbergia accessions from 20 forest divisions of Kerala and Tamil Nadu regions were used in the present study. Based on the Evanno method, Bayesian model of population structure analysis divides the tree accessions into 3 genotypic groups, namely D. sissoides group-1, D. sissoides group-2 and D. latifolia group. The tree accessions were also divided into 2 distinct clusters (D. latifolia and D. sissoides clusters) according to Neighbour joining clustering and principal co-ordinates analysis. AMOVA, allelic frequency analysis and Mantel test were performed for both species. The results indicated that D. latifolia and D. sissoides were genetically distinct without any recent intermixing. The results also expressed that D. sissoides cluster consists of 2 genotypes which contained recently admixed individuals. The present work was proved that D. latifolia is primitive than D. sissoides and both are considered as a monophyletic sibling species. 32 out of 40 D. sissoides accessions showed D. latifolia-like leaflet apex in the Western Ghats of Kerala and Tamil Nadu. It was formed a species complex which caused misidentification of D. sissoides accessions as D. latifolia. The study will be useful for the species identification, mapping of populations, species conservation and further genetic improvement programs.
Key words: Cryptic sister species, Bombay Blackwood, Indian Rosewood, Malabar Blackwood, PCR based Dominant DNA marker, Binary data analysis.
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