Abstract Detail

Systematics

ASHOKAN, AJITH [1], SALONY, SUSNATA [1], SARYAN, PREETI [1], GOWDA, VINITA [1].

The ginger lilies of the Indomalayan realm: a complex case of recent divergence and reticulate evolution.

The genus Hedychium (known as ginger lilies, Zingiberaceae) is represented by at least 80 species and is distributed across seven biodiversity hotspots in the Indomalayan realm (IMR)- the Western Ghats and Sri Lanka, Himalaya, Mountains of the Southwest China, Indo-Burma, Sundaland, Wallacea, and the Philippines. Hedychium is known for its taxonomic complexity due to high intraspecific and low interspecific variation in its morphological and molecular characters. Earlier subgeneric classifications of Hedychium were mainly based on six-seven morphological characters and the first-ever molecular phylogenetic reconstruction of the genus failed to support these previous subgeneric classifications (only internal transcribed spacer (ITS) region of the nuclear ribosomal DNA was used). The new molecular phylogenetic tree proposed four distinct clades based on their geographical distribution, however, it failed to provide resolution to the interspecific relationships and represented <30% of the known diversity within the genus. Moreover, hyperdiverse ecoregions like the Western Ghats and Sri Lanka, Eastern Himalaya, Northeast India, and Northern Thailand were not well represented in this analysis.
To obtain a clear resolution within the genus Hedychium and to understand its biogeography, we reconstructed a time-tree of Hedychium. We used two nuclear (ITS, CaM) and five plastid markers (ccsA, matK, rps16, trnL, trnQ-psbK) across 70% of the recognized species from all major geographic regions and calibrated the phylogenetic tree using Zingiberalean fossils. We used both Bayesian and likelihood frameworks to answer the following questions: (i) What was the origin of the genus Hedychium? (ii) Are species complexes in Hedychium a result of recent radiation, physiological constraints, an ecological construct, or all of the above? Our preliminary phylogenetic analyses support the monophyly of Hedychium with four major clades which are restricted to specific geographic regions and further diversification events within the Indo-Burma ecoregion. Molecular dating and biogeographic reconstruction showed that the age of the most recent common ancestor coincided with the collision of Indian and Eurasian plates, further supporting the "out-of-India" hypothesis. Based on crossing experiments, genome size analysis and geographic distributions we also found that both polyploidization and hybridization events have occurred multiple times in the genus Hedychium resulting in reticulate evolution and hence lack of resolution among closely related taxa. We propose that the remarkable species diversity and presence of unresolved species complexes are outcomes of the ecology, lack of physiological compartmentalization, and recent radiation of this genus in IMR.

Related Links:
Tropical Ecology and Evolution (TrEE) Lab

1 - Tropical Ecology and Evolution (TrEE) Lab, Department of Biological Sciences , Indian Institute of Science Education and Research (IISER) Bhopal, Bhauri, Bhopal, Madhya Pradesh, 462066, India

Keywords:
Hedychium
Indomalayan realm
phylogeny
Zingiberaceae.

Presentation Type: Oral Paper
Session: COOL1, ASPT Cooley Award Talks
Location: Tucson C/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 8:15 AM
Number: COOL1002
Abstract ID:260
Candidate for Awards:George R. Cooley Award