RESEARCH: EVOLUTION, DIVERSIFICATION AND BIOGEOGRAPHY OF CICADAS ON THE INDIAN SUBCONTINENT
Most of the scientific knowledge on Indian biodiversity is 60 to 100 years old, dating back to the pre-independence era. During this time, there have been tremendous scientific developments in areas such as evolution, molecular phylogenetics, biogeography, and conservation genetics. This has substantially advanced our understanding of the evolution and dispersion of biodiversity on earth. Much of this development has largely excluded India, which is unfortunate considering the crucial biogeographic role that the Indian Subcontinent plays. India is at the junction of Palearctic and Oriental zoogeographic regions, and is believed to have been critical in the evolution and exchange of many important faunal elements across these zoogeographic regions. Thus, understanding the evolution and biogeography of Indian faunas is important in constructing a more complete picture of biological diversification in the Palearctic and Indo-Australian Regions. Using cicadas as a tractable invertebrate group, we are aiming to: (a) study the origin and diversification of cicadas in India in relation to neighboring regions, (b) generate a higher-level phylogeny of Indian cicadas that will form a backbone of all subsequent studies, and (c) help inventory cicada diversity, including cryptic species, with help of molecular data. We are achieving this by intensively sampling cicadas across the length and breadth of India, DNA sequencing, phylogenetic methods and recently developed genomic methods.
Cicadas are excellent for studying biogeographic patterns and associated biology due to the following reasons: (1) Ease of collecting: Cicada males can be easily collected in the daytime by following their loud songs. Cicadas of both sexes come to light at night. (2) Acoustic signals: Songs of cicadas are highly species-specific and facilitate rapid gathering of distributional data. Similar to other sexually selected traits, cicada songs often diverge during early stages of speciation and can reveal cryptic species. (3) Life History: Long-lived fossorial juveniles and short-lived arboreal adults lead to low dispersal rates, high levels of phylogeographic structure within species, and clear differentiation among species. (4) Distribution: Cicadas occupy a broad range of habitats, and they are distributed on all continents except Antarctica. They are known from a few Mesozoic and ~35 Cenozoic fossils.
We would like to understand the mechanisms and timescales behind the diversification of cicadas on the Indian subcontinent. Our work combines a highly diverse insect group that has considerable representation and endemism in the Indian subcontinent, with a vast and complex landscape that has a long history spanning an unusually broad range of geological and climatic processes. This combination will enable us to elucidate mechanisms responsible for insect diversification on the Indian subcontinent.
This work is in collaboration with Prof. Chris Simon (Univ. of Connecticut, USA) and will contribute to a global phylogeny of cicadas. It is partially funded by the National Academy of Sciences (“NAS”, USA) and USAID's Partnerships for Enhanced Engagement in Research (PEER) Science Grant (2013-2015), and startup funds from the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru.
Price, B. W., E. L. Allan, K. Marathe, V. Sarkar, C. Simon, and K. Kunte. 2016. The cicadas (Hemiptera: Cicadidae) of India, Bangladesh, Bhutan, Myanmar, Nepal and Sri Lanka: an annotated provisional catalogue, regional checklist and bibliography. Biodiversity Data Journal, 4:e8051. PDF file (1.3MB).