Étudiants CSBQ

Shivaprakash Nagaraju

Concordia University
Candidat Ph.D.

superviseur(e): Selvadurai Dayanandan
Début: 2011-09-01

Patterns of evolutionary diversification of Myristicaceae members in the Indian sub continent
Myristicaceae is a medium sized family of angiosperm trees and shrubs with a wide pan-tropical distribution consisting of 21 genera and nearly 500 species. They are largely confined to lowland rainforest habitats. Along with Annonaceae, Magnoliaceae and three other monogeneric families they belong to (Magnoliales). Most of the species are large trees and they are valued for timber and non-timber forest products (NTFPs). In India, the Myristicaceae are represented by 5 genera (Gymnocranthera, Knema, Myristica, Endocomia and Horsfieldia) and nearly 21 species including the cultivated nutmeg Myristica fragrans. Within the Indian sub-continent they occur in wide range of habitats such as fresh water swamps, tidal forest and evergreen and semi evergreen forests. In southern India they form a unique ecosystem called the freshwater Myristica swamps dominated by Myristicaceae plant species. These Myristica swamps harbors rich biodiversity including endemic flora and fauna and also play a major role in conserving ground water. Due to the availability of perennial water source in the Mysristica swamps, many of them have been usurped and converted for paddy and arecanut cultivation; indeed many of the existing swamps are severely threatened due to acute fragmentation of the swamps caused by agricultural activities. My doctoral thesis is focused on understanding the patterns of evolutionary diversification of Myristicaceae members within the Indian subcontinent. I employ combination of molecular phylogenetic and population genetic tools to track colonization history and diversification of Myristicaceae members within Indian subcontinent. I specifically address three questions using molecular phylogenetic tools 1) What are the patterns of colonization of the Myristicaceae members in the Indian sub-continent (into India or out of India hypothesis) , 2) Within the Indian sub-continent how did they come to colonize the three major wet-zones (Western Ghats, North-east India and Andaman and Nicobar Islands) and 3) What are the patterns of evolution and diversification of the Myristicaceae members across different habitats ranging from swampy (wet) to non-swampy habitats (dry) habitats. Finally, I use population genetics and ecological niche models to understand the influence of habitat quality on genetic diversity and fitness of Myristicaceae members. I have chosen Gymnocranthera canarica, a Myristicaceae member endemic to the Western Ghats, India to address this question. The findings from my thesis will contribute to understanding of colonization history and diversification of one of the economically important and unique plant family Myristicaceae within the Indian subcontinent. My thesis will also contribute to improved understanding of evolution of wet-zone flora in the Indian subcontinent. These findings will not only be important for the advancement of theoretical knowledge, but also valuable for planning conservation programs to mange genetic resources of wet zone taxa, which are continuously being threatened by anthropogenic activities

1- Tertiary Origin and Pleistocene Diversification of Dragon Blood Tree (Dracaena cambodiana-Asparagaceae) Populations in the Asian Tropical Forests
Jian-Li Zhao, Lu Zhang, Selvadurai Dayanandan, Shivaprakash Nagaraju, Dong-Mei Liu, Qiao-Ming Li
2013 PLoS ONE

2- Genetic structure and diversity of Coscinium fenestratum: a critically endangered liana of Western Ghats, India
Thriveni, H. N., R. C. Sumangala, K. N. Shivaprakash, G. Ravikanth, R. Vasudeva, H. N. Ramesh Babu
2013 Plant Systematics and Evolution

3- Do Ecological Niche Model Predictions Reflect the Adaptive Landscape of Species?: A Test Using Myristica malabarica Lam., an Endemic Tree in the Western Ghats, India
Shivaprakash K. Nagaraju, Ravikanth Gudasalamani, Narayani Barve, Jaboury Ghazoul, Ganeshaiah Kotiganahalli Narayanagowda, Uma Shaanker Ramanan
2013 PLoS ONE