Ullasa Kodandaramiah
IISER Thiruvananthapuram
Ullasa Kodandaramaiah is Professor in the School of Biology at the Indian Institute of Science Education and Research Thiruvananthapuram and Principal Investigator of the Vanasiri Evolutionary Ecology Lab. He earned his Ph.D. in Animal Ecology from Stockholm University, with post-doctoral research at the University of Cambridge. Prof. Kodandaramaiah’s work focuses on evolutionary ecology, phylogeography and diversification of butterflies and other taxa in the Western Ghats and tropical landscapes. He explores how environmental history, species traits and biogeography interact to shape biodiversity. He has been elected Fellow of the Indian Academy of Sciences in recognition of his scientific contributions.
Session 3A: Symposium on Evolutionary Ecology in the Wild
Chairperson: Renee Borges, IISc, Bengaluru
Hybridization and diversification of Impatiens in the Western Ghat
The Western Ghats mountain system harbours exceptional diversity of Impatiens plants, shaped by isolation, adaptation, and hybridization. I present results from two studies on Impatiens of the northern Western Ghats — one on ecological specialization and local adaptation, and another on hybridization dynamics. Populations of I. lawii, confined to high-elevation “sky islands,” show striking floral divergence among nearby populations. Common-garden experiments confirmed that these differences are genetically based rather than environmentally induced. Floral variation was not explained by pollinator assemblages or by genetic and environmental distances, suggesting strong localized selection on floral traits. In a second study, we discovered a narrow hybrid zone between I. rosea and I. balsamina. Greenhouse and genetic analyses confirmed hybrid identity and indicate that the zone arose through secondary contact between species with incomplete prezygotic barriers. The narrowness of the hybrid zone likely reflects the combined effects of inbreeding, local adaptation and pollinator preferences, with evidence for unidirectional introgression by I. balsamina. Together, these studies reveal how niche specialization, geographic isolation, and hybridization drive Impatiens diversification in the Western Ghats.