Format: ORAL

Vinita Gowda1, Preeti Saryan1, Aleena Xavier1, and Ajith Ashokan1,2

1 Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal (IISER Bhopal), Bhopal, India 2 Department of Biology, University of Missouri, St. Louis, USA

The genusHedychium(Zingiberaceae), distributed in the Asian tropics, is riddled with species complexes. Species complex refers to a set of taxa that lack morphological distinctness from each other, rendering species boundaries among them to be very hazy. To understand speciation in the genus Hedychium, we tackled species complexes as well as phylogenetic reconstructions simultaneously using morphological, ecological, molecular, and genomic approaches. We first noted that the number of species complexes was highest in the Indo-Burmese region, the centre of diversity for Hedychium. Using a machine learning approach we analyzed morphological characters of taxa within a complex and we noted that individuals from different species were found to cluster together based on sympatry. This suggested that sympatry may have played a role in maintaining hazy species boundaries. We next looked at intra- and inter-specific reproductive barriers by carrying out directional crossing experiments in the wild, where male and female parents were tracked in each treatment. Although past horticultural studies had indicated the potential forHedychiumsto hybridize, our results emphasize the need to look at sympatric associations and directionality in reproductive barriers, especially in taxonomic groups known for the presence of species complexes. Finally, we mapped the flowering phenology and we concluded that the 4-5 months of overlapping flowering phenology of closely related and reproductively compatible taxa may have also facilitated the inter-species crosses in this genus. Our phylogenetic reconstruction of the genus Hedychium,thereforeshows signatures of hybridization, facilitated by the lack of reproductive-isolation mechanisms. This is further enabled by factors such as sympatric associations and the timing of flowering. What is interesting is that, despite this, the clades were stable and showed biogeographic affiliations. Diversifications in Hedychium were mostly shaped by geological events such as the uplift of the Himalayasand environmental factors like monsoon intensification.