Understanding the causal processes that have generated the stunning biodiversity in tropical forests has been fundamental to ecological and evolutionary research. In this talk, I will explore the role of the geographical, geological and ecological processes on biogeography and diversification among two arthropod groups (centipedes and butterflies) at different spatial scales, the Western Ghats in peninsular India and the South and Southeast Asia. To this end, I have integrated multiple lines of evidence, including DNA sequences, morphological traits, and data from geology, climate, and ecology, finding that geographic and geo-climatic processes have played an important role in diversification in both centipedes and butterflies. While some of the molecularly-delineated centipede species did not exhibit morphological divergence, they occupied distinct climatic niches across the Western Ghats, suggesting ecological speciation. Butterflies showed morphological variation in wing patterns and mimicry, which are thought to be involved in ecological adaptation. However, there was no significant effect of wing pattern diversity, and mimicry detected on diversification rates, indicating that geographic factors played an important role in their diversification. These two case studies highlight the need to assess multiple ecological and evolutionary axes when examining diversification patterns and processes. I will follow this by demonstrating the use of molecular phylogenies and biogeography to understand community assembly of species, which has traditionally been studied from under an ecological lens. I will show that evolutionary history, biogeographic isolation, and stochastic colonisation influence assembly of mimetic butterfly communities.
Towards the end, I will talk about my future research, where I plan to focus on exploring processes that influence extant diversity patterns using multiple soil arthropods taxa that vary across evolutionary and ecological gradients. Currently, such multi-taxa and multi-disciplinary studies are lacking in India and are limited to few studies in the world. I hope insights from these studies will contribute towards our understanding to broader questions in evolutionary biology such as: How did tropical biodiversity originate and how is it maintained? Why are the tropics so species rich? Why are some lineages more diverse than others? Also, I hope to contribute substantially towards understanding arthropod evolution and systematics in one of the most biodiverse and less explored regions in the world.