Population Diversity of Tecomella undulata across South Asia: Diversity identification Markers, Possible Causes, and Potential for Conservation

Abstract

Tecomella undulata (Sm.) Seem., the sole species of its genus in the family Bignoniaceae, is a keystone tree of the arid and semi-arid tracts of South Asia, valued equally for its ecological role in desert stabilization and its long history of use in traditional medicine. Habitat fragmentation, unsustainable timber and herbal extraction, weak natural regeneration, grazing pressure and a warming/drying climate has together pushed the species toward endangered status in the Thar Desert of Sindh, Pakistan. Since there is a lack of such study which integrate anatomical, phytochemical, and molecular analysis as diversity identification markers, this review explores and summarizes the available information on population diversity identification using molecular (chiefly ISSR and RAPD), anatomical structure and the phytochemical profile as markers to understand variations in T. undulata populations. Published marker-based work shows substantial genetic diversity retained within populations despite geographic isolation, while anatomical and phytochemical surveys, though comparatively sparse, point to xeromorphic adaptations and stress induced shifts in secondary metabolism that likely track local aridity and soil conditions. We argue that combining molecular, anatomical and phytochemical data is not simply additive but necessary though other approaches like common garden experiment may also be needed to fully distinguish genetically fixed divergence from environmentally plastic response, and thereby to identify populations that are both genetically distinct and ecologically or medicinally valuable. This information would give conservation planners, across South Asian range, an evidence based strategy for prioritizing germplasm collection, in situ protection, and restoration efforts before further population decline erodes the genetic resources