Abstract Detail

Systematics

ASHOKAN, AJITH [1], GOWDA, VINITA [1].

Phylogenetic systematics, historical biogeography and character evolution in the taxonomically complex genus Hedychium J.Koenig (Zingiberaceae).

The genus Hedychium (ginger lilies; ~90 species) is included in the ginger family, Zingiberaceae, and is distributed across all the seven biodiversity hotspots in the Indo-Malayan Realm (IMR). Hedychium is known for its taxonomic complexity due to high intraspecific and lower interspecific variation in its morphological and molecular characters. The only molecular phylogenetic tree of Hedychium recovered 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. To obtain a clear resolution about its origin and to understand its biogeography, we reconstructed a time-tree of Hedychium. We used two nuclear (CaM, ITS) and five plastid markers (ccsA, matK/trnK, rps16, trnL, trnQ-psbK) across 80% of the known species from all major geographic regions to answer the following questions: (i) How many species are included in Hedychium and how are they related to each other? (ii) When and where did these species evolve?, and (iii) When and how did the considerable variation of floral morphological characters arise in Hedychium? Our phylogenetic analyses support the monophyly of Hedychium with three major clades and a grade that are restricted to specific geographic regions and further ecological and morphological diversification events within the Indo-Burma ecoregion. Divergence dating and ancestral range reconstruction revealed that Hedychium originated in the Early Miocene of Indo-Burma, further supporting the ‘into-India’ hypothesis. Based on the insights from the phylogenetic reconstruction, crossing experiments, genome size estimation, and ploidy determination, we found that hybridization and polyploidization events have occurred multiple times in Hedychium, resulting in reticulate evolution which has made it difficult to delimit species boundaries among closely related taxa. We propose that the remarkable species diversity and presence of unresolved species complexes are outcomes of spatiotemporal overlap in flowering, lack of reproductive isolation, and recent radiation within the Indo-Burma ecoregion, especially in Northeast India, Southwest China and Northern Thailand.

1 - Indian Institute of Science Education and Research Bhopal, Biological Sciences, Bhopal By-Pass Road, Bhauri, Bhopal, Madhya Pradesh, 462066, India

Keywords:
gingers
Indo-Malayan Realm
phylogeny
polyploidy
speciation
Systematics.

Presentation Type: Oral Paper
Session: SYS4, Systematics IV: Monocots part B to Rosids part A
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 1:30 PM
Number: SYS4005
Abstract ID:530
Candidate for Awards:None