Format: ORAL

Aleena Xavier * and Vinita Gowda

Tropical Ecology and Evolution (TrEE) Lab, Indian Institute of Science Education and Research (IISER) Bhopal, Madhya Pradesh, India.

Widely distributed species often harbour high levels of genetic and phenotypic variations due to their interactions with diverse environmental conditions. This makes them an ideal study group to understand the microevolutionary processes that can lead to speciation. Their wide distribution allows us to investigate the genetic and physical barriers to gene flow across both spatial and temporal scales. Our study focuses on Hedychium spicatum, a morphologically variable, widespread ginger found in the understory of tropical montane forests. It is distributed across high-elevational regions of India, Southern China, and Northern Thailand and is found in sympatry with congeners. Ecological studies have shown that H. spicatum can interbreed with congeneric, sympatric taxa. This led us to hypothesize that the morphological variation seen in this species could be due to hybridization events. We aim to investigate putative barriers to gene flow in H. spicatum across its geographical range. We sampled 12 H. spicatum populations and sympatric congeneric species across their distributional range. We used dd-RAD sequencing and SSR markers to investigate the genetic structure of this species using model-based and model-free clustering approaches. We also checked for different genetic isolation models, migration models, demographic history, mating dynamics, and ploidy variations to understand the determinants of the genetic diversity of this species. Our results showed migrations between different geographical regions, and we found evidence of genetic admixtures between H. spicatum and its sympatric taxa. We propose that the structure of H. spicatum is affected by a combination of factors such as migrations, historical demographic processes, hybridization events, and ploidy variations. Understanding the complex interaction of these factors could be critical in understanding plant speciation mechanisms in the tropics, an area where we still have limited knowledge.