Abstract Detail

Population Genetics/Genomics

Xavier, Aleena [1], Gowda, Vinita [2].

Convoluted complexes: role of hybridization and introgression in shaping plant species complexes in tropics (Hedychium spicatum Complex, Zingiberaceae).

Hedychium, commonly known as ginger lilies, is a taxonomically complex genus of perennial rhizomatous herbs with a pan-Asian distribution. The taxonomic complications in this genus stem from the high intraspecific and low inter-specific morphological variations which have given rise to several species complexes. Our study focuses on Hedychium spicatum which is one of the early-diverging and widely distributed taxa in this genus that forms a species complex, the Spicatum complex. This complex currently consists of at least six taxonomically distinct species and two putative hybrid forms which are distributed across two different clades. H. spicatum provides us with an interesting case wherein its distributional range overlaps with that of the other members of the complex and shows interfertility with its sympatric congeners. In addition to this, morphological analysis of the Spicatum complex using an unsupervised machine learning approach inferred multiple clusters within H. spicatum, where some of the H. spicatum individuals clustered with non- spicatum taxa from the complex. This makes the spicatum complex an ideal system to investigate the role of geographic barriers, reproductive isolation, hybridization and introgression in shaping the morphological diversity within this complex. We propose that geographically distinct forms of spicatum will show local introgressions with their sympatric congeners, thus explaining its regionally variable morphological characters. We used a dd-RAD sequencing approach to sample genome-wide SNPs to understand phylogeographic patterns and population genetic structures of the taxa within the spicatum complex and test their species limit. We sampled 11 populations of H. spicatum from throughout its distributional range along with its sympatric congeneric taxa that are part of the Spicatum complex and their intermediate forms (n=57). We used a combination of model-based and model-free clustering approaches to understand the population structuring of H. spicatum. In our analysis, most of the non- spicatum individuals were separated from the spicatums with certain non-spicatums nested within H. spicatums and the putative hybrid forms show admixture between H. spicatum and non- spicatums. These results suggest hybridization between spicatum and non- spicatum individuals. However, the clustering of H. spicatum individuals lacked a strong geographic signature. This could be either because of hybridization, multiple migration events or a result of multiple reproductive strategies (clonal propagation vs selfing vs outcrossing) adopted by the plant in the different geographic locations. Overall, the Spicatum complex represents a strong case of complex speciation events that may be common in young plant groups such as the genus Hedychium, resulting in blurred species boundaries and the formation of taxonomic species complexes.

1 - Indian Institute of Science Education and Research Bhopal, Biological Sciences, TrEE Lab,(Lab no 303) AB-3(CELL), IISER Bhopal, Bhopal bypass road, Bhopal, MP, 462066, India
2 - IISER Bhopal, Room 223, AB3, Dept. Of Biological Sciences,, IISER- Bhopal, Bhopal Bypass Road, Bhauri,, Bhopal, MP, 462066, India

dd RAD
Asian tropics
Tropical Botany.

Presentation Type: Oral Paper
Number: PGG3002
Abstract ID:540
Candidate for Awards:Margaret Menzel Award

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