Diversity and guild structure of spiders in poyya pokkali rice agroecosystem, a range disjunct landscape in Thrissur, Kerala, India
- MPhil EI 2017-2018
Background: Spiders play a very significant role in ecology by being exclusively predatory and thereby regulate insect populations. In India, Arachnology is still in its infancy compared with the breadth and depth of entomological research. Spiders represent a diverse and functionally important group of arthropods and the assessment of their status can provide much information useful in monitoring the integrity of biotic communities. The pokkali rice is a nutrient rich saline resistant variety of rice cultivated along the coastal ares of Thrissur, Alappuzha and Ernakulam district of Kerala. A pioneering study was conducted to document the spider diversity associated with Poyya pokkali rice agroecosystems of Thrissur district. Additionally an attempt was also made to characterize the cytochrome oxydase C subunit 1 (CO1) of salticid spider, Phintella vittata (C.L. Koch, 1846) based on spiders collected from four districts of Kerala. Methods: Extensive faunistic surveys of spiders in altitudinally different sites of Poyya Grama Panchayath was carried out for four months form December, 2017 to March, 2018. Spiders collected from different quadrates by hand picking and sweeping methods once in a week. The spiders collected were arranged into different functional groups or guilds, according to their ecological characteristics relating to foraging manner. Diversity indices were calculated. For molecular studies, spiders preserved in absolute alcohol and sequencing of DNA of different individuals of Phintella vittata using universal markers were carried out and p-distance analysis and Maximum Likelihood Trees were prepared. The Results: A total of 5,213 individuals belonging to 76 species coming under 50 genera and 20 families were collected and dealt with. A mygalomorph species Annandaliella ernakulamensis was also reported. Twenty eight species are reported as endemic to India. Field photographs and microphotographs are provided. A checklist is prepared on collected spiders and arranged them into seven feeding guilds based on their foraging mode. The diversity indices analysis of spiders was also performed and it varies among different sites and most diverse sampling locality was found to be Chenthurunni with a value of 3.54 and 0.95 for Shannon-Weiner and Simpson Indices respectively, shows a stable ecosystem. The p-distance value obtained among the spiders collected from different localities was found to be trivial, though a positive correlation with the geographic distance and genetic distance could be established. Conclusion: Being lied in the Western Ghats, the Poyya Pokkali rice agroecosystem was hypothesised to possess a rich and diverse araneofauna. This hypothesis are satisfied by the outcome of this study. In fact, this scanty effort represents only a splinter of the fauna of Poyya pokkali rice fields. As this region with diverse climates and natural background, further investigations will certainly reveal many more species of spiders. The present study envisaged an in-depth study of the diversity and feeding behaviour of spiders of this biodiversity hotspot and shed some effort to bring this otherwise neglected animal group onto the conservation radar screen. The molecular study was carried out using two universal primers, hence the confinement in modest use of primers may also one of the reason s for the less divergence among spider individuals studied. Nevertheless, the results from this analysis have improved our understanding of intra-specific relationships among the spiders. Keywords: Spider diversity, Phintella vittata, p-distance, Guilds, Pokkali rice, Thrissur, Kerala , India.
SPIDER DIVERSITY PHINTELLA VITTATA P-DISTANCE GUILDS POKKALI RICE THRISSUR KERALA INDIA