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Research Interests

My research interests fall into two broad categories. The idea of phenotypic variation, brought about both at the group level and at the individual level by means of behavioral flexibility or developmental plasticity, is a common thread that runs through both these research areas. I am interested both in the mechanistic questions of how these phenomena are brought about as well as how selection acts on the individuals to bring about and maintain phenotypic variation.

I am working on the first set of questions for my PhD; I am using both empirical studies as well as theoretical modeling to address these questions. Irrespective of which of these research interests I pursue in the future, I would like to continue to use a combination of theoretical and empirical approaches to answer my questions. I am not a modeler by training; but I am getting into individual-based models which I believe are enormously powerful and well suited for studies in ecology and evolution.

I. Emergence of complexity in biological systems

The path-breaking theories of kin selection and reciprocal altruism triggered the establishment of the field of social behaviour. Though we've made remarkable progress in testing ultimate questions about the evolution of sociality, we are only now beginning to get a handle on how coordinated collective behaviour involving interactions of numerous individuals is achieved. The group-level phenomenon that is achieved is termed as an "emergent" property of the group, since the output is a non-linear function of individual actions. In other words, it is "more than a sum of its parts".   The individuals constituting the group do not have a global perspective of group-level phenomena; instead they rely on cues or signals available to them that are very local in nature. The questions that keep me awake include:

1) What behavioral rule or set of rules (often considered "simple") do individuals follow that results in the observed emergent group level phenomena?

2) When dealing with diverse environments, how is flexibility at the group level achieved?

3) How does selection shape rules at the individual level?

II. The development and maintenance of phenotypic variation in a population

Phenotypic variation achieved as a consequence of variation in developmental pathways (phenotypic polymorphism) is ubiquitous in nature. In a given population, phenotypic polymorphism for a trait can either be a set of discrete phenotypes (polyphenism) or phenotypic variation can be more graded. The phenotypes achieved as a consequence of following different developmental routes are thought to be adaptive or optimal for that environment. The questions that intrigue me are:

1) How does the complex interplay of genetic variation and environmental cues lead to varying developmental trajectories of an organism?

2) What are the costs and constraints of phenotypic variation achieved in this manner?

3) Do the resultant phenotypes show optimal fitness if they are raised in an environment that is predicted by cues (environmental and genetic) obtained during development?  

4) Is there selection on the developmental mechanisms to "pay more attention" to the more reliable cues about the environment they will experience?

Study system and current research

Umbonia crassicornis   (Hemiptera: Membracidae) is a neotropical treehopper with maternal care. The female lays a single clutch of eggs on her host plant and when the nymphs hatch, they live in a tightly clustered aggregation close to the mother extending up to a few centimeters along the stem. Their mother sits below the aggregation and protects nymphs from an array of predators during their development. Predators, even flying predators, are more likely at attack the ends of an aggregation. When a predator approaches the aggregation, the nymphs produce a coordinated group signal repeated at regular intervals. These signals are transmitted to the mother as plant-borne vibrations. The mother responds by approaching the predator, walking up to it, and kicking at it with her hind legs to drive it away.

Questions:

1) Are the group signaling patterns sensitive to the position of the predator (Top-end versus bottom-end)?

2) If the mother does have predator-location cues available to her in the group signals, does she use them to locate the predator?

3) How are the different group level patterns produced by nymphs? In other words, what are the local rules used by nymphs that result in the varying patterns of group signals?