Theses and Dissertations

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    Diversity and Ecology of Odonates in Coimbatore District
    (SACON, 2017) Muhil, M Suhirtha; Pramod, P
    The global biological diversity is to be treated as a wealth considering its potential role in ecosystem sustenance and management. The declining status and vulnerability of biological diversity to various human-induced problems, compels us to index and preserve species and their habitats as a continuous and crucial process. Exploding human population, degrading environment and loss of habitats are three major reasons for the irreversible loss of biological diversity especially in the tropics (Wilson, 1988). To understand the causes behind the ecological and evolutionary processes responsible for the rich biodiversity and also the ecosystem service biodiversity provides, it is very essential to know how many species inhabit this earth (May, 2011). There are presently 1.9 million catalogued species in the world of which nearly one million are insects (Chapman, 2009), while the estimated number of global species by taxonomists is between three and 100 million species (May, 2010). This estimation of biodiversity based on taxonomic patterns varies from the estimates based on macroecolgical patterns and diversity ratios. Erwin (1982) estimated 30 million species of Arthropods, based on the host specificity of guilds in beetle samples and subsequent hierarchical ratio extrapolations.
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    The Effect of Land-use Changes on Odonate Assemblages in the Central Western Ghats
    (Wildlife Institute of India, Dehradun, 2024) Gowda, H.N. Rakshit; Gautam, Ritesh; Johnson, J.A.
    Odonata, the only apex insect predator in both terrestrial and aquatic life forms, are widely used as biological indicators of the health of aquatic ecosystems across the globe. The Riparian land uses such as commercial plantations negatively impact the Odonata assemblages, causing the homogenisation of habitats with generalist species and the extinction of specialist species. These land uses affect the riparian vegetation, habitat structure, and water quality parameters, which are crucial for Odonates to complete their life cycle. To understand the impact of commercial plantations on stream-associated Odonata assemblages at the sub-order level, three treatments comprising a combination of forest and areca plantations on either bank of streams were selected. The habitat variables, such as ambient temperature and canopy cover, along with stream parameters like flow and water quality parameters such as pH and water temperature, significantly influenced the Odonate assemblages. The sub-orders, Dragonflies and Damselflies, differed in their response to altered (Areca plantations and plantation-forest edge) and preserved sites (forested sites). These outcomes highlight the importance of the dependency of Odonata on particular sets of variables and the consideration of suborders of Odonata separately as indicator groups for the quality of aquatic ecosystems.