Abstract Detail

Reproductive Processes

Xavier, Aleena [1], Saryan, Preeti [2], Gowda, Vinita [3].

Lack of reproductive isolation and environmental niche overlap explains the presence of species complexes in the genus Hedychium.

Species complexes pose an interesting challenge in understanding the origin of species and its evolution. However, in plants, most of the studies have mainly focused on identifying taits that may be important for species delimitation. Here in this study, we explore the origin of species complexes, factors maintaining these complexes, and their implications in species diversity. The genus Hedychium (Zingiberaceae) is known to harbor at least 10 species complexes and preliminary studies have identified three types of species complexes, nomenclatural complexes- formed due to discrepancies in taxonomic description, polyploid complexes, and ecological complexes. We define ecological complexes as complexes comprising taxa that share morphological similarities due to inter-species hybridization, often aided by sympatry. We studied three ecological and nomenclatural complexes and asked the following questions: (i) Do taxa that form species complexes show higher interspecies compatibility rates? ii) Do taxa that form species complexes share a similar environmental/climatic niche? iii) What is the role of widely distributed taxa in the reproductive network of the complexes and the genus Hedychium?
Methods: We performed interspecies crosses in congeneric sympatric populations across North-East of India (n = 193 treatments) and also collected data from the literature (n = 782 treatments). For environmental niche construction, we used elevation and19 bioclimatic layers that represent temperature and precipitation variables from the Worldclim database.
Results: We found that the interspecies compatibility decreases as the genetic distance between the two species increases (rho = -0.2582, p-value = 0.2458). Interestingly, one species complex comprised of taxa from multiple clades whereas two complexes comprised of taxa from a single clade. Interspecies-crosses within a complex showed a high success rate (87% and 75%). Both environmental niche overlap and environmental niche similarity showed a complex-dependent pattern. Environmental niches were not equivalent (Peq >0.05) among taxa within a complex. We also found that all the three complexes comprised of at least one widespread taxa which interact with narrow spread taxa in sympatric populations and give rise to ecological species complexes. Network analysis was performed to visualize the effect of the distributional pattern on interspecies compatibility. We found that the linkage density for the widespread taxa was 3.23 while it was 1.75 for the rest of the taxa. Partner diversity in both maternal and paternal was high (maternal= 0.89, paternal=1.08) for the widespread taxa compared to the narrow one (maternal= 0.47, paternal=0.45).
Conclusion: We conclude that in the genus Hedychium, ecological complexes are principally a result of interspecies hybridization among sympatric, co-flowering congeners which leads to sharing of morphological features among taxa. Therefore, interspecies hybridization and environmental niche may affect both the origin and the maintenance of 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 - C/o Parmeshwar Singh Negi, VPO Mebar, Tehsil Kalpa, District Kinnaur, Kinnaur, HP, 172107, India
3 - IISER Bhopal, Room 223, AB3, Dept. Of Biological Sciences,, IISER- Bhopal, Bhopal Bypass Road, Bhauri,, Bhopal, MP, 462066, India

species complex
environmental niche.

Presentation Type: Oral Paper
Number: RP5005
Abstract ID:1059
Candidate for Awards:None

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