Abstract Detail

Tropical Biology

Xavier, Aleena [1], Saryan, Preeti [2], GOWDA, VINITA [1].

Leaky barriers and lack of boundaries: Understanding species complexes in the genus Hedychium J.Koenig.

The genus Hedychium J.Koenig (Zingiberaceae, gingers) is composed of perennial, rhizomatous herbs that prefer shady, moist habitat and are distributed across Asian paleotropics. Many species in this genus lack morphological uniqueness, giving rise to species complexes. We hypothesize that the absence of environmental niche divergence and interspecific reproductive compatibility has led to the formation of species complexes within the genus. We are testing this hypothesis by investigating the environmental niche characteristics (niche breadth and overlap) and the reproductive compatibility of the following Hedychium species: H. coronarium, H. stenopetalum, H. forrestii,  H. spicatum, and H. ellipticum.
We collected environmental characteristics and occurrence records of the above taxa for niche analysis from field records, BHPL herbarium, GBIF database, publications, and PhD theses. The bioclimatic data and the elevation data in 30-arc second resolution was downloaded from the WorldClim database. The correlation between different biogeoclimatic variables in our study area was calculated in R using Raster and R was also used for all statistical tests. Niche breadth (Levin’s B) was calculated in the environmental space using both ordination based method as implemented by the package ecospat and using ENM based method using MaxEnt as implemented by the package ENMTools. Environmental niche divergence between the taxa was quantified using the niche overlap metrics( Schoener’s D and Hellinger’s H). To check for our hypothesis of niche divergence, both niche equivalency and niche similarity randomizations were performed and the test was performed using ENM based metric as well as ordination based metric. The compatibility was checked by performing interspecific crosses in the wild plant populations. 
Under niche equivalency randomization, the hypothesis of niche divergence was rejected for all the species pairs except for H. spicatum- H.coronarium (p- value= 0.034) and H. spicatum- H. ellipticum ( p- value= 0.001), whereas under the similarity randomization, the hypothesis of niche divergence was rejected for all the species pairs as expected since closely related taxa tend to occupy similar niches but not the equivalent ones. Physiological compatibility experiments carried out in the field show that H. spicatum and H. ellipticum are compatible with each other and H. coronarium, H. stenopetalum and H. forrestii are compatible with each other. These results indicate that cross-compatibility and the lack of niche divergence are responsible for the formation of some species complexes in Hedychium whereas in others despite niche divergence, the lack of physiological reproductive barrier gives rise to species complexes.

1 - Indian Institute of Science Education and Research Bhopal, lab no : 303, AB-3, IISER Bhopal, Bhopal, Madhya Pradesh, 462066, India
2 - IISER Bhopal, Near Bhauri Village, Bhopal, AB3, Biological Sciences, IISER Bhopal, Near Bhauri Village, Bhopal, Bhopal, MP, 462066, India

niche analysis
cross compatibility
Species Complex.

Presentation Type: Poster
Session: P, Tropical Biology Posters
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 5:00 PM Time and date to be determined
Number: PTB006
Abstract ID:829
Candidate for Awards:None

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